Intervention Protocol

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Adaptation of shift work schedules for preventing and treating sleepiness and sleep disturbances caused by shift work

  1. Thomas C Erren1,*,
  2. Christine Herbst1,
  3. Melissa S Koch1,
  4. Lin Fritschi2,
  5. Russell G Foster3,
  6. Tim R Driscoll4,
  7. Giovanni Costa5,
  8. Mikael Sallinen6,
  9. Juha Liira7

Editorial Group: Cochrane Occupational Safety and Health Group

Published Online: 23 JUL 2013

DOI: 10.1002/14651858.CD010639


How to Cite

Erren TC, Herbst C, Koch MS, Fritschi L, Foster RG, Driscoll TR, Costa G, Sallinen M, Liira J. Adaptation of shift work schedules for preventing and treating sleepiness and sleep disturbances caused by shift work (Protocol). Cochrane Database of Systematic Reviews 2013, Issue 7. Art. No.: CD010639. DOI: 10.1002/14651858.CD010639.

Author Information

  1. 1

    University Hospital of Cologne, University of Cologne, Institute and Policlinic for Occupational Medicine, Environmental Medicine and Prevention Research, Cologne, Germany

  2. 2

    University of Western Australia, Western Australian Institute for Medical Research, Crawley, West Australia, Australia

  3. 3

    University of Oxford, Nuffield Department of Clinical Neurosciences; Circadian and Visual Neuroscience, Oxford, UK

  4. 4

    The University of Sydney, School of Public Health, Sydney, New South Wales, Australia

  5. 5

    University of Milan, Department of Occupational Health, Milan, Italy

  6. 6

    Finnish Institute of Occupational Health, Centre of Expertise for Human Factors at Work, Team of Working Hours and Cognitive Ergonomics, Helsinki, Finland

  7. 7

    Finnish Institute of Occupational Health, Research and Development in Occupational Health Services, Helsinki, Finland

*Thomas C Erren, Institute and Policlinic for Occupational Medicine, Environmental Medicine and Prevention Research, University Hospital of Cologne, University of Cologne, Kerpener Str. 62, Cologne, 50937, Germany. tim.erren@uni-koeln.de.

Publication History

  1. Publication Status: New
  2. Published Online: 23 JUL 2013

SEARCH

 

Background

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Acknowledgements
  6. Appendices
  7. Contributions of authors
  8. Declarations of interest

The International Labour Office (ILO 1990) defines working in shifts as: "...a method of organization of working time in which workers succeed one another at the workplace so that the establishment can operate longer than the hours of work of individual workers." Shift work is very common. For example, according to the World Health Organization, 15 to 20% of employees in Europe and the USA work according to some type of shift system (IARC 2010).

Shift work in general, and night-shift work in particular, increase the rate of work-related accidents (Wagstaff 2011). In addition, shift work may be associated with a variety of adverse physical and psychological problems including coronary heart disease (Puttonen 2010), cancer (Erren 2010) and depression (Driesen 2011). Established complaints among shift workers are difficulties in getting enough sleep, and maintaining an acceptable level of alertness while working irregular hours, both of which may lead to an increased risk of errors and accidents (Akerstedt 2011; Landrigan 2004).

 

Description of the intervention

Since shift work allows work to be done outside of the 'normal' working hours, it is not surprising that many shift systems exist and are adapted to the needs of workplaces (ILO 2004). This review focuses on the idea of adapting the shift schedule, as an intervention, in order to minimise negative health effects. Common shift systems in health care or police work (Rajaratnam 2011) are rotating shifts with lengths varying between 8 and 12 hours. Generally speaking, staying on one shift for at least a week is considered a slow rotation, while a fast rotation means changing shift from as often as every day to every two to three days. In forward rotation one changes from one shift to the next by starting the next shift later than the last one. In backward rotation one starts the next shift earlier than the last one (see for example Bambra 2008).

Three 8-hour or two 12-hour work shifts in 24 hours are common in nursing and in manufacturing. They can be undertaken with fast and with slow rotation. One of the slowest rotations is in the offshore petroleum industry, where employees may work 14 consecutive days or nights. The first week may be a 12-hour day shift and the next week a 12-hour night shift, followed by several weeks off. Twenty-four-hour shifts are common in firefighting and in medicine. Split shifts, where workers routinely work more than one short shift in a 24-hour period (e.g. four hours in the morning and four hours in the evening) can be found among service occupations such as in the restaurant industry (ILO 2004).

 

How the intervention might work

In order to minimise the adverse effects of shift work, and increase worker satisfaction, the International Labour Organization recommends shift work schedules with the following characteristics (ILO 2004):

  1. a short cycle period with regular rotas;
  2. individual workers work few nights in succession;
  3. individual workers have some free weekends with at least two full days off;
  4. short intervals between shifts be avoided;
  5. flexibility regarding shift change times and shift length.

These recommendations seem to be based on a non-systematic review of the evidence and on experts' opinions, and are recommendations that can also be found elsewhere (Knauth 2003). Some of the above recommendations (numbers 3 and 5) aim to decrease social isolation associated with certain shift systems . Others are common recommendations to avoid sleepiness and sleep disturbances. Short rest periods between shifts, many night shifts and long shifts are all associated with sleepiness and sleep disturbances or adverse health effects (Akerstedt 1998; Akerstedt 2011; Bambra 2008; Cotter 2011; Driscoll 2007; Erren 2010; Li 2011). Therefore shift systems with shorter shifts, faster rotation and longer periods of rest are hypothesised to minimise the adverse effects of shift work. Some experts believe that forward rotation is more beneficial than backward rotation (Driscoll 2007; Knauth 1995). However, it is not unambiguously settled whether forward or backward shift rotation is more or less favourable (Driscoll 2007; Foster 2005).

In the airline industry, fatigue risk management systems are recommended by international organisations such as the International Civil Aviation Organization (ICAO), the International Air Transport Association (IATA) and the International Federation of Airline Pilots' Associations (IFALPA) (ICAO 2011). In short, fatigue risk management systems go beyond limitation of flight and duty time. Their bases are data collection on sleepiness based on 'scientific principles' and continuous monitoring of fatigue risks in order to reduce these risks. Teaching personnel about sleep hygiene and optimising sleep in rest periods are some of the additional measures that may be included in such a fatigue risk management system.

 

Why it is important to do this review

To date, a number of systematic reviews have examined the effects of shift work schedules on work-related criteria (Baltes 1999), neurobehavioral and physiological outcomes (Driscoll 2007) and health outcomes (Bambra 2008). The latter two reviews also examined sleep outcomes and fatigue and alertness outcomes. While Bambra 2008 concluded that a forward rotation is beneficial, Driscoll 2007 concluded that the evidence was inconclusive. Similarly fast rotation was considered beneficial by Bambra 2008 but not by Driscoll 2007.

The reviews by Driscoll 2007 and Bambra 2008 included before-and-after trials with only one before and one after measurement and without control groups. Bias due to time trends is common in such trials, and can be reduced if the review is limited to trials with several measures of the outcomes before and after the intervention. In addition, neither of the reviews used the Cochrane Collaboration's rigorous methodology for the literature search, the selection of trials and contacting of study authors. Shift work trials are often not published in commonly-available scientific outlets. Therefore, searching grey literature may yield additional trials. From previous experience in the field we know that it may be difficult to identify eligible trials by their abstracts alone. Searching in duplicate and contacting authors for additional information may improve the quality of data for meta-analysis.

 

Objectives

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Acknowledgements
  6. Appendices
  7. Contributions of authors
  8. Declarations of interest

To assess the effects of adaptation of shift schedules for preventing and treating sleeping and alertness problems in shift workers.

 

Methods

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Acknowledgements
  6. Appendices
  7. Contributions of authors
  8. Declarations of interest
 

Criteria for considering studies for this review

 

Types of studies

We will include:

  • randomised controlled trials
  • randomised cross-over trials, in which participants are randomly allocated to one of two groups; one group receives the active intervention and then the control intervention, and the other group receives the control and active interventions in the other order (see Higgins 2011, Chapter 16.4)
  • cluster randomised trials
  • controlled before-after trials: non-randomised trials in which the intervention takes place in one group but not in another, which serves as a control group. The outcomes are measured once before and once after the intervention.
  • (non-randomised) cross-over trials: the same as cross-over trials above, but allocation is not random
  • interrupted time series: uncontrolled before-after trials that have measured the outcomes at least three times before the intervention and three times after the intervention.

For possible meta-analyses we will have the following groups:

  • randomised trials including cluster randomised trials and randomised cross-over trials
  • controlled-before after trials including non-randomised cross-over trials,
  • interrupted time series.

We will also examine laboratory trials. We define laboratory trials as trials in which recruited individuals are subject to the intervention in a laboratory setting, not their respective workplace. We will present data from laboratory studies in a separate table, and use the data for comparison in the Discussion section, rather than for primary decision making.

We will include studies reported as full-text, those published as abstract only, and unpublished data.

 

Types of participants

We will include any adult workers (age > 18) in shift work schedules that include night shift work, irrespective of industry, country, age or co-morbidities. We will describe and analyse studies examining treatments for workers with sleep disorders separately from those examining general, unselected worker populations. We will also include laboratory studies of people in simulated night shift work in a table in the Discussion section (see above).

 

Types of interventions

We will include any intervention that deals with a shift work schedule. Both the intervention and the control group (or data) should examine the effects of shift work schedules. Any intervention that includes a change in the shift work schedule will be included.

 

Types of outcome measures

 

Primary outcomes

Sleep-wake disturbance associated with shift work is one of the core health problems of shift workers. In order to characterise the sleep-wake disturbance, we will include studies that have measured intervention effects with the following outcome measures:

  1. Sleep quality off shift: measured with a validated questionnaire such as the Bergen Insomnia scale (Pallesen 2008), Pittsburg Sleep Quality Index (Buysse 1989), Basic Nordic Sleep Questionnaire (Partinen 1995), Jenkins Sleep Questionnaire (Lallukka 2011), Karolinska Sleepiness Scale (Kaida 2006), relevant questions in the Standard Shift Work Index, or wrist-worn actigraphy-based measures. These questionnaires measure more than just sleep quality. However we are only interested in the questions relating to sleep quality and sleep length. We will also accept sleep quality as measured in sleep diaries.
  2. Sleep length off shift: Average length of sleep based on the relevant questions in validated questionnaires (see examples above) or on sleep diaries, or wrist-worn actigraphy.
  3. Sleepiness during shift: Sleepiness measured at the beginning, middle and end of the shift. The disadvantage of sleepiness outcomes is that they are measured at specific time points and do not provide overall measures for sleepiness. Sleepiness can be operationalised as:
    1. Self-rated (subjective) sleepiness measured with a validated questionnaire such as the Karolinska Sleepiness Scale (Kaida 2006), Stanford Sleepiness Scale (Herscovitch 1981; Hoddes 1972), relevant questions in the Standard Shift Work Index (Barton 1995), or other visual analogue scales, or
    2. Physiological sleepiness measured by electrophysiological methods while working (e.g. electroencephalogram or electro-oculogram measurement while driving a train) or by standardised physiological tests of sleepiness such as the Multiple Sleep Latency Test (Carskadon 1986), the Maintenance of Wakefulness Test (Mitler 1982) or the pupillometric assessment, or
    3. Behavioural sleepiness measured as performance in a validated vigilance test such as the Psychomotor Vigilance Test (e.g. Basner 2011; Thorne 2005), the MackWorth Clock Test (Mackworth 1950), or single or multiple-choice reaction time tests, or
    4. behavioural sleepiness measured as characteristics of overt behaviour that are identified through video recording methods such as an Observer Rating of Drowsiness (e.g. Wierwille 1994), or PERCLOS (percentage of eyelid closure) (Dinges 1998; Sommer 2010).

Fatigue usually refers to exhaustion or tiredness due to long-lasting exertion. However, because there are some differences in the use of these terms in different countries (e.g. between Europe and Australia), we will also include fatigue as an outcome measure when it is used as a measure of sleepiness at work. Therefore, we will include studies measuring fatigue at any moment during the shift as a self-reported outcome measured with a validated questionnaire or interview.

 

Secondary outcomes

In studies that report primary outcomes of this review we will examine the following secondary outcomes:

  • number of staff
  • number of hours worked
  • overtime
  • staff costs

A full cost-effectiveness analysis is beyond the scope of this review, as it would require information not only on our primary outcomes and their 'value' (e.g. willingness to pay) but also of potential adverse effects of shift systems such as errors or injuries and their costs and 'values'. Errors and injuries in shift workers are being evaluated in another Cochrane review (Ker 2009).

 

Search methods for identification of studies

 

Electronic searches

We will search the following databases from inception to the present:

  1. MEDLINE (Ovid)
  2. EMBASE (Embase.com)
  3. Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library)
  4. Web of Knowledge (http://isiknowledge.com/ )
  5. http://www.opengrey.eu/
  6. PsycINFO (ProQuest)r
  7. ProQuest Dissertations & Theses
  8. NIOSHTIC (OSH-UPDATE);
  9. NIOSHTIC-2 (OSH-UPDATE);
  10. HSELINE (OSH-UPDATE);
  11. CISDOC (OSH-UPDATE);

We present search strategies for the first six databases as Appendix 1; Appendix 2; Appendix 3; Appendix 4; Appendix 5 and Appendix 6. As we will conduct another Cochrane review assessing the effects of person-directed non-pharmacological interventions for preventing and treating sleep disturbances caused by shift work (Herbst 2013) in conjunction with this review, we will run only one joint systematic search to avoid needless duplication of work. We will search Proquest using subject headings and keywords (defined by the authors of the publications) only.

Since the search term 'shift' alone leads to a very high number of citations, we have included many relevant combinations of the term 'shift' with other terms used to describe specific shifts. Examples are shift work, night shift, shift schedule and graveyard shift. We also account for terms that describe shift work, but do not use the word 'shift'. such as duty time or hours (e.g. transport industry), rota (medicine) or the 4-day week alias compressed work week used to denote a series of 12-hour shifts. The search is limited by terms for different outcomes or types of interventions. Since only abstracts are searched, we have included terms near, but not exactly covered by the inclusion criteria. A second limitation is by type of trial (not for all databases).

 

Searching other resources

We (CH, MK) will check reference lists of all primary studies and review articles for additional references. We will contact experts in the field to identify additional unpublished materials. We (GC, MK) will search the conference proceedings of the biannual symposium on shift and night work. We (CH, MK) will search the World Health Organization Trial Register (www.who.int/ictrp/) as well as the most important trial registers within this register directly (www.clinicaltrials.gov; https://www.clinical trialsregister.eu/).

 

Data collection and analysis

 

Selection of studies

Two review authors (CH, MK) will independently screen titles and abstracts for inclusion of all the potential studies we identify as a result of the search and code them as 'retrieve' (eligible or potentially eligible/unclear) or 'do not retrieve'. We will retrieve the full-text study reports and two review authors per study (CH, MK) will independently screen them for inclusion. They will also identify and record reasons for the exclusion of ineligible studies. We will resolve any disagreement through discussion or, if required, we will consult a third person (TE). We will identify and exclude duplicates and collate multiple reports of the same study so that we include studies rather than reports of studies in the review. We will record the selection process in sufficient detail to complete a PRISMA flow diagram and 'Characteristics of excluded studies' table. We will also seek to obtain further information from the study authors when a paper is found to contain insufficient information to enable us to reach a decision on eligibility.

 

Data extraction and management

Two review authors per study (CH, TD, LF, MK, GC, JL, RF) will independently extract data from each of the included trials. We will extract the following information and present it in the review:

  • methods: type of trial, allocation, inclusion criteria, statistical analysis
  • basic information: country, dates of study (beginning and end of allocation or study), duration of study, number of participants, number of participants evaluated, information about shift schedules
  • basic information about the participants: age, sex, occupations, chronotype (morningness-eveningness score or similar)
  • intervention: details of interventions being compared, other interventions also performed at the same time
  • which outcomes were measured, their definitions, which ones are reported
  • outcome data for the outcomes relevant to this systematic review
  • funding for trial, and notable conflicts of interest of trial authors.

For randomised laboratory studies we will briefly extract the following:

  • inclusion criteria,
  • details of the interventions compared, including any interventions performed at the same time in both groups,
  • number of participants,
  • country and duration of the trial,
  • which outcomes were measured and how, and
  • results of outcomes relevant to this review.

 

Assessment of risk of bias in included studies

Two review authors per study (CH, MK, TD, LF, JL, RF) will independently assess the risk of bias of the included studies. We will consult a third review author (TE) when disagreements occur, and mutual agreement will be obtained. If information is absent for evaluation of the methodological criteria, we will contact the trial authors to seek additional information. Where possible, we will use quotes from the text to support the review authors' judgements.

We will use the Cochrane 'Risk of bias' tool for all study types. In order to avoid empty Risk of Bias tables for certain studies and many additional tables, we will construct a single list of domains that can be used to assess all studies in the review. We will write "not relevant to this study type" in Risk of Bias domains not relevant to the study type.

 

Randomised controlled trials

We will use the 'Risk of bias' tool according to the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011) as implemented in the RevMan software program. We will select 'Unclear' risk of bias if there is insufficient information to evaluate the domain.

We will evaluate the following domains (taken directly or modified where applicable from Higgins 2011):

  1. random sequence generation:
    1. We will consider a trial to be low risk of bias if it describes a random element in sequence generation, such as using:
      1. a random number table,
      2. a computer random number generator,
      3. coin tossing,
      4. shuffling cards or envelopes,
      5. throwing dice,
      6. drawing lots,
      7. or minimisation.
    2. We will consider a trial to be high risk of bias if the authors describe sequence generation using:
      1. odd or even date of birth,
      2. or a rule based on e.g. work record number.
  2. allocation concealment:
    1. We will consider a trial to be low risk of bias if it reports:
      1. central allocation (including telephone, web-based and pharmacy-controlled randomisation),
      2. or sequentially-numbered, opaque, sealed envelopes.
    2. We will consider a trial to be high risk of bias if it reports:
      1. using an open random allocation schedule (e.g. a list of random numbers),
      2. assignment envelopes without appropriate safeguards (e.g. if envelopes were unsealed or non­opaque or not sequentially numbered),
      3. alternation or rotation,
      4. date of birth,
      5. record number,
      6. or any other explicitly unconcealed procedure.
  3. blinding of participants and personnel: We will omit this domain as it is not possible to blind participants or organising personnel to different shift schedules.
  4. blinding of outcome assessors (evaluated for each outcome separately):
    1. We will consider a trial to be low risk of bias if:
      1. there is no blinding of outcome assessment, but the review authors judge that the outcome measurement is not likely to be influenced by lack of blinding, or
      2. blinding of outcome assessment is ensured, and it is unlikely that the blinding could have been broken.
    2. We will consider a trial to be high risk of bias if:
      1. there is no blinding of outcome assessment, and the outcome measurement is likely to be influenced by lack of blinding, or
      2. there is blinding of outcome assessment, but it is considered likely that the blinding could have been broken, and the outcome measurement is likely to be influenced by lack of blinding.
  5. incomplete outcome data (evaluated for each outcome separately):
    1. We will consider a trial to be low risk of bias if:
      1. there are no missing outcome data,
      2. reasons for missing outcome data are unlikely to be related to the true outcome,
      3. missing outcome data are balanced in numbers across intervention groups, with similar reasons for missing data across groups,
      4. in dichotomous outcome data, the proportion of missing outcomes compared with the observed event risk is not large enough to have a clinically-relevant impact on the intervention effect estimate,
      5. in continuous outcome data, a plausible effect size (difference in means or standardised difference in means) among missing outcomes is not large enough to have a clinically-relevant impact on observed effect size, or
      6. missing data have been imputed using appropriate methods.
    2. We will consider a trial to be high risk of bias if:
      1. the reason for missing outcome data is likely to be related to the true outcome, with either imbalance in numbers or reasons for missing data across intervention groups,
      2. in dichotomous outcome data, the proportion of missing outcomes compared with observed event risk is large enough to induce clinically-relevant bias in the intervention effect estimate,
      3. in continuous outcome data, the plausible effect size (difference in means or standardised difference in means) among missing outcomes is large enough to induce clinically-relevant bias in observed effect size,
      4. ‘as-treated’ analysis done with substantial departure of the number of participants assigned at randomisation (or beginning of the trial),
      5. there is potentially inappropriate application of simple imputation, or
      6. in cluster randomised trials, loss of full clusters is likely to introduce bias.
  6. selective outcome reporting
    1. We will consider a trial to be low risk of bias if:
      1. the study protocol is available and all of the study’s pre-specified (primary and secondary) outcomes that are of interest in the review have been reported in the pre-specified way, or
      2. the study protocol is not available but it is clear that the published reports include all expected outcomes, including those that were pre-specified (convincing text of this nature may be uncommon).
    2. We will consider the trial to be of high risk of bias if:
      1. not all of the study’s pre-specified primary outcomes have been reported,
      2. one or more primary outcomes is reported using measurements, analysis methods or subsets of the data (e.g. sub-scales) that were not pre-specified,
      3. one or more reported primary outcomes were not pre-specified (unless clear justification for their reporting is provided, such as an unexpected adverse effect),
      4. one or more outcomes of interest in the review are reported incompletely so that they cannot be entered in a meta-analysis, or
      5. the study report fails to include results for a key outcome that would be expected to have been reported for such a study.
  7. outcome reliable or objectively measured (for each of the outcomes relevant to the review)
    1. We will consider the outcome to have a low risk of bias if the outcome is measured objectively (e.g. psychomotor vigilance test) or two or more raters have an agreement > 90% or kappa => 0.8.
    2. We will consider the outcome to have a high risk of bias if two or more raters have an agreement < 90% or kappa < 0.8.
  8. other sources of bias. We will mention any other sources of bias identified in this field.

 

Randomised cross-over trials

We will assess all items for randomised controlled trials and in addition we will assess the following domain. We will report 'unclear' risk of bias if there is insufficient information to evaluate the domain.

  • applicability of the design for every outcome
    • We will consider trials to be of low risk of bias if:
      • the interaction between order of interventions and outcome was examined and no statistically-significant interaction was identified, or
      • we believe the outcome to be independent of the order of treatments, for example if the wash out period is long enough.
    • We will consider trials to be of high risk of bias if:
      • an interaction between order of interventions and outcome was identified in the analysis, or
      • we judge the outcome measure to be influenced by the order of treatments, for example if the wash-out period is very short.

 

Cluster randomised trials

We will assess all items for randomised controlled trials in addition to the domains below.We will report 'unclear' risk of bias if there is insufficient information to evaluate the domain.

  • recruitment bias (e.g. Puffer 2003). Recruitment of individuals to different clusters after randomisation may occur. This may lead to different types of participants being recruited to the different clusters. Should there be evidence of this which may change the interpretation of the results, we will consider the trial to be at high risk of bias. We will consider trials to be of low risk of bias if we judge the effect of recruitment to different clusters after randomisation not to influence the outcome, or if the trial reports no or minimal recruitment after randomisation.
  • appropriate statistical analyses. These trials do not always take the cluster effect into account.
    • We will consider the trial to be of low risk of bias if:
      • the analysis takes the cluster effect into account (see section 16.3 in Higgins 2011), or
      • the analysis can be corrected provided the following information is available a) the number of clusters (or groups) randomised to each intervention group or the average (mean) size of each cluster b) the outcome data ignoring the cluster design for the total number of individuals (for example, number or proportion of individuals with events, or means and standard deviations) and c) an estimate of the intracluster (or intraclass) correlation coefficient (ICC) (section 16.3.4 in Higgins 2011).
    • We will consider the trial to be at high risk of bias if the analysis does not take the cluster effect into account and the analyses cannot be corrected.

 

Interrupted time series

Ramsay 2003 offers a risk of bias assessment method for interrupted time series. We will assess all items included in Ramsay 2003,with the addition of selective outcome reporting. Items 3 (blinding of outcome assessors), 4 (outcome measure reliable) and 5 (incomplete data) in that list are included in the 'Risk of bias' tool for assessing randomised controlled trials, described above.

We will use domains four to seven from the above list for randomised controlled trials in addition to the domains below. We are therefore following Ramsay 2003, but adding 'selective outcome reporting'. We will report 'unclear' risk of bias if there is insufficient information to evaluate the domain.

  1. intervention done independently of other changes over time
    1. We will consider the study to have a low risk of bias if we judge based on reports that the intervention was independent of other changes over time.
    2. We will consider the study to have a high risk of bias if we judge based on reports that the intervention was not independent of other changes over time.
  2. intervention unlikely to affect data collection
    1. We will consider the study to have a low risk of bias if we judge based on reports that the intervention was unlikely to affect data collection e.g. same sources and methods of data collection before and after the intervention.
    2. We will consider the study to have a high risk of bias if we judge based on reports that data collection was likely affected by the intervention.
  3. shape of the intervention effect prespecified
    1. We will consider the study to have a low risk of bias if a rational explanation for the shape of intervention effect was given by the author(s) of the study.
    2. We will consider the study to have a high risk of bias if the explanation for the shape of intervention effect is inadequate.
  4. rationale for the number and spacing of data points
    1. We will consider the study to have a low risk of bias if an (adequate) rationale for the number of points is stated (e.g., monthly data for 12 months post-intervention was used because the anticipated effect was expected to decay) or a sample size calculation was performed that influenced the study design and used reasonable assumptions.
    2. We will consider the study to have a high risk of bias if an (adequate) rationale for the number of points is not available from the author(s) and no, or an inadequate, sample size calculation was performed.
  5. appropriate statistical analyses
    1. We will consider studies to have a low risk of bias if:
      1. autoregressive integrated moving average (ARIMA) models were used, or
      2. time series regression models were used to analyse the data and serial correlation was adjusted/tested for, or
      3. we can correct the analyses.
    2. We will consider the trial to be at high risk of bias if none of the above were done/are possible.

 

Controlled before-after studies

We will use domains four through eight of the randomised controlled trials 'Risk of bias' tool, and items one and two of the assessment for interrupted time series, to assess the risk of bias in controlled before-after studies. However, two important sources of bias relevant for controlled before-after trials are not covered by the above. We will report 'unclear' risk of bias if there is insufficient information for evaluation.

  • baseline differences between groups. We will consider the variables type and place of work, age, sex and chronotype.
    • We will consider studies to have a low risk of bias if these four variables are reported to be similar.
    • We will consider studies to have a high risk of bias if the authors judge based on the reports that one of these variables differs enough to introduce bias.
  • appropriate statistical analyses
    • We will consider studies to have a low risk of bias if the analysis is considered adequate or can be corrected.
    • We will consider studies to have a high risk of bias if the analysis is considered inadequate, for example if:
      • it does not report baseline data and changes from baseline for both participants in the intervention group and controls, or
      • confounding is not adequately addressed in the analysis.

 

Non-randomised cross-over trials

In addition to the assessment of risk of bias for randomised cross-over trials, we will assess the additional items listed at controlled before-after studies above.

 

Assessment of bias in conducting the systematic review

We will conduct the review according to this published protocol and report any deviations from it in the 'Differences between protocol and review' section of the systematic review.

 

Measures of treatment effect

We will enter the outcome data for each study into the data tables in RevMan software (RevMan 2012). We will enter data as point estimates, standardised mean differences (SMDs) and their standard deviation (SD) when multiple scales are mixed, or mean and SD for continuous outcomes when the same scale is used. Should we obtain only dichotomised data for a continuous outcome, we will use these data. We will contact the authors aiming to obtain continuous data. If only effect estimates and their 95% confidence intervals (CIs) or standard errors are reported in studies we will enter these data into RevMan using the generic inverse variance method. When the results cannot be entered in either way, we will describe them in the 'Characteristics of included studies' table, or enter the data into Additional tables. We will reverse the scoring of scales if needed, so that a high score will denote the same direction (good or bad) in all outcomes. Different study designs will not be mixed. We will use STATA for calculations not possible within RevMan.

For controlled before-after studies, we will plot the outcome measurements both at baseline and follow-up to ensure that baseline imbalances are taken into account.

For cross-over studies we will examine the interaction between the order of treatments and outcome, where possible.

For time-series studies, we will extract data from original papers and re-analyse them according to recommended methods for analysis of interrupted time series designs for inclusion in systematic reviews (Ramsay 2003). These methods utilise a segmented time-series regression analysis to estimate the effect of an intervention while taking into account secular time trends and any auto-correlation between individual observations. If an included interrupted time series study uses a control group, we will use the difference in rates between the intervention and the control group as the outcome. For each study, we will fit a first-order auto regressive time-series model to the data using a modification of the parameterisation of Ramsay (Ramsay 2003). Details of the mode specification are as follows:

Y= ß0 + ß1time + ß2 (time-p) I (time > p) + ß3 I (time > p) + E, E ˜ N (0, s2).

For time = 1,...,T, where p is the time of the start of the intervention, I (time > p) is a function which takes the value 1 if time is p or later and zero otherwise, and where the errors E are assumed to follow a first order auto regressive process (AR1). The parameters ß have the following interpretation: ß1 is the pre-intervention slope. ß2 is the difference between post and pre-intervention slopes. ß3 is the change in level at the beginning of the intervention period, meaning that it is the difference between the observed level at the first intervention time point and that predicted by the pre-intervention time trend.

We will standardise the data of interrupted time series studies in order to obtain effect sizes by dividing the outcome and standard error by the pre-intervention standard deviation as recommended by Ramsay 2003. Thus we will have two separate outcomes for an interrupted time series study: the short term change in the level of outcome due to the intervention which can be interpreted as an additive effect, and the long term change in the trend in time or change of slope which indicates an increasing effect of the intervention.

 

Unit of analysis issues

For studies that employ a cluster-randomised design and that report sufficient data to be included in the meta-analysis but that do not make an allowance for the design effect, we will calculate the design effect based on the methods described in chapter 16.3.6 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). If no reliable estimate of the intra-cluster correlation coefficient (ICC) is available from the literature but the other data are available, we will include the trial using an ICC of 0.1. Currently the authors are unaware of ICCs for trials in shift workers. Of published ICCs, we deem the ones provided by the Health Services Research Unit to be most applicable to trials in shift workers (ICC Database). The ICCs range from 0 to 0.32, with most coefficients being below 0.1. We will follow the methods stated in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011) for the calculations.

 

Dealing with missing data

We will contact trial authors to obtain data not found in their reports that are needed for the assessment of risk of bias, or data for outcomes relevant to this systematic review. We will use all reports of trials in order to obtain missing data, including presentations, if found. We will use the methods presented in the Cochrane Handbook (Higgins 2011) chapter 7.7.3.3 to calculate statistics (e.g. standard deviations or correlation coefficients) that can be calculated from other values.

If possible, we will use intention-to-treat (ITT) analyses in randomised trials and similar analyses of the full group in non-randomised trials. The following information may be of relevance in order to assess the impact of missing data: distribution by intervention group and by baseline variables (age, sex etc) as well as by responses on a first questionnaire (when multiple questionnaires are used). We will examine reasons for drop-out and missing data if these data are available. We will record the methods study authors used for dealing with missing data.

Missing data may be a strong source of bias. Sensitivity analyses will examine the effect of trials with high and low rates of missing data.

We do not aim to undertake imputation of data. The extent of missing data may be so severe that even imputation may lead to biased estimates of the effect.

 

Assessment of heterogeneity

Within each comparison of interventions and each outcome, we will assess the homogeneity of the results of included studies based on similarity of interventions, populations, exact outcome definition, outcome timing and follow-up.

We will separately analyse studies in shift workers and persons with shift work disorder. We will explore other differences in population in subgroup analyses (see Subgroup analysis and investigation of heterogeneity).

We will consider studies to be similar enough to be combined with regard to outcome if they use the same outcome (e.g. sleepiness) measured at a similar time with regard to the shifts examined. All different ways of measuring one outcome will be considered similar enough for the primary analysis. Differences in outcome definitions will be examined in subgroup analyses. When a study reports an outcome in more than one way, we will use the subjective measure of sleepiness, sleep quality from sleep diaries and sleep length from sleep diaries in the main analysis.

With regard to interventions, we anticipate combining the following (types of) comparisons:

  • comparison of two different lengths of shift (e.g. 8 versus 12 hour shifts) in studies where the speed (slow, fast, fixed) and type (backward, forward, none) is the same in both groups. We will combine these studies in a primary analysis irrespective of speed and type of rotation.
  • comparison of backward versus forward rotation in studies where the length of shifts and the speed of rotation are the same in both groups. We will combine these studies in a primary analysis irrespective of length of shift, speed of rotation and other details of the shifts.
  • comparison of slow versus fast rotation in studies where the length of shifts and the direction of rotation are the same in both groups. We will combine studies if shift lengths constitute the same number of hours, irrespective of the direction of rotation and the length of shifts.
  • mixed comparisons, where more than one element of shift schedules differs between the two groups.
  • flexible and fixed shift scheduling.
  • different starting times of shifts.

We will test for statistical heterogeneity by means of the Chi2 test as implemented in the forest plot in Review Manager 5 software (RevMan 2012). We will use a significance level of P < 0.1 to indicate whether there is a problem with heterogeneity. Moreover, we will quantify the degree of heterogeneity using the I2 statistic, where an I2 value of 25% to 50% indicates a low degree of heterogeneity, 50% to 75% a moderate degree of heterogeneity and > 75% a high degree of heterogeneity (Higgins 2011).

If we identify substantial heterogeneity we will report it and explore possible causes by prespecified subgroup analysis.

 

Assessment of reporting biases

We will reduce the effect of reporting bias by including studies and not publications in order to avoid the introduction of duplicated data (i.e. two articles could represent duplicate publications of the same study). Following the Cho 2000 statement on redundant publications, we will attempt to detect duplicate studies and, if more articles report on the same study, we will extract data only once. We will prevent location bias by searching across multiple databases. We will prevent language bias by not excluding any article based on language. We will construct and analyse funnel plots to assess the likelihood of small study bias if more than five trials are included in a comparison. We will use the test proposed by Egger 1997 if we can include more than 10 trials in a comparison. We will assess selective reporting of outcomes in sensitivity analyses (see Sensitivity analysis).

 

Data synthesis

We will first present results separately for randomised studies, controlled before-after studies and interrupted time series. We will pool data from studies judged to be homogeneous (see Assessment of heterogeneity) using Review Manager 5 software. If possible, we will combine studies using incidence data or for trials reporting continuous data, standardised mean differences (SMDs). To make the SMDs more readily interpretable for clinicians, we will then recalculate the pooled SMD into a mean difference by multiplying the SMD by the median standard deviation taken from included studies using the preferred scale in question. We will meta-analyse sleep length as mean differences.

When studies are found to be heterogenous (i.e. dissimilar in terms of intervention, outcome, population or follow-up time) we expect to find them also statistically heterogenous. Therefore, we consider a random-effects model more appropriate for meta-analysis. All estimates will include a 95% confidence interval (CI). For analyses not possible within Review Manager software, we will use STATA or other statistical software.

We will use the GRADE approach as described in the Cochrane Handbook (Higgins 2011) and as implemented in the GRADEPro 3.2 software (GRADEpro 2008) to present the quality of evidence and 'Summary of findings' tables.

The downgrading of the quality of a body of evidence for a specific outcome will be based on five factors:

  1. Limitations of study,
  2. Indirectness of evidence,
  3. Inconsistency of results,
  4. Imprecision of results,
  5. Publication bias.

The GRADE approach specifies four levels of quality (high, moderate, low and very low).

 

Subgroup analysis and investigation of heterogeneity

If we find several studies that have investigated similar interventions and have used the same or very similar outcome measures at the same or similar follow-up times, we will conduct the following subgroup analyses:

  1. Chronotype (or similar). Rationale: sleep-wake disturbances on, for example, night shifts are different for people with different chronotypes or different chronobiological propensity (Erren 2013).
  2. Shift schedule details. Rationale: details of shift schedules may influence sleepiness:
    1. for shift length studies: different types of rotation.
    2. for direction of rotation studies: speed of rotation and length of shift.
    3. for speed of rotation studies: direction of rotation and length of shift.
  3. Occupational settings or branches of industry (e.g. hospital staff). Rationale: work differs in different industries by physical and psychological strain, thus affecting sleepiness, for example.
  4. Different ways of measuring the same outcome. Rationale: For example, actigraphy for sleep length may be more exact, yet limited to a smaller time range than sleep diaries, which give a better overall picture.
  5. Mean or median age. Rationale: older shift workers have more experience with shift work and may have adapted better to shift work or may be persons whose chronotypes are better suited to shift work, as people not suited to shift work will have left shift work (selection effects).

 

Sensitivity analysis

We plan to conduct the following sensitivity analyses:

  • each of the domains of the 'Risk of bias' assessment; for selective outcome reporting each outcome by selective reporting of the other outcomes,
  • differences in measuring the same outcome (e.g. self reported versus physiological sleepiness)
  • different assumptions for imputation of missing data, different proportions of missing data
  • different assumptions for intra-class correlation (for cluster randomised trials)
  • fixed-effect model.

 

Acknowledgements

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Acknowledgements
  6. Appendices
  7. Contributions of authors
  8. Declarations of interest

We thank Dr. Kathrin Bauer for the idea of doing a Cochrane Review within the Department of Occupational Medicine in Cologne. We thank Leena Isotalo for advice and help with the search strategy. We also thank the Managing Editor Jani Ruotsalainen and Coordinating Editor Jos Verbeek from the Cochrane Occupational Safety and Health Review Group for their help.

 

Appendices

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Acknowledgements
  6. Appendices
  7. Contributions of authors
  8. Declarations of interest
 

Appendix 1. Medline OVID search strategy

1. exp Chronobiology Disorders/
2. exp Sleep Disorders/
3. exp Circadian Rhythm/
4. exp "wounds and injuries"/ OR occupational injuries/
5. (errors OR incidents OR accidents OR mistakes OR safety).tw.
6. Death, Sudden, Cardiac/ OR Death, Sudden/ OR death?.tw. OR Death/
7. exp "costs and cost analysis"/
8. (econom$ OR cost OR costs).tw.
9. (chronotherapy OR light OR daylight OR dark OR darkness).tw.
10. exp sleep disorders, intrinsic/ OR exp "sleep initiation and maintenance disorders"/
11. (sleep OR sleepiness OR circadian OR vigilance OR altertness OR alert OR wakefulness OR drowsiness OR fatigue OR insomnia OR hypersomnolence OR dyssomnia OR eveningness OR morningness OR "concentration difficulties" OR attentiveness OR arousal OR performance OR vigilance OR vigilant).tw.
12. (nap OR napping OR rest OR resting).tw.
13. 1 OR 2 OR 3 OR 4 OR 5 OR 6 OR 7 OR 8 OR 9 OR 10 OR 11 OR 12
14. ((shift OR shifts) adj1 (rota OR system OR systems OR schedul* OR hours OR time OR pattern$ OR cycle OR extend$ OR evening OR late OR roster OR early OR weekend OR twilight OR graveyard OR night$ OR split OR non-standard OR "non standard" OR flex$ OR turnaround OR continuous OR rotat$)).tw.
15. (day adj2 schedule?).tw.
16. (rota OR roster OR 'day week' OR flexitime OR 'hours of work' OR nightshift* OR shiftwork*).tw.
17. ((work$ OR duty) adj1 (shift OR shifts OR rota OR system OR systems OR schedul* OR hours OR time OR pattern$ OR cycle OR extend$ OR evening OR late OR roster OR early OR weekend OR twilight OR graveyard OR night* OR split OR non-standard OR "non standard" OR flex$ OR turnaround OR continuous OR rotation$)).tw.
18. ((backward OR forward OR rapid OR slow OR rapidly OR slowly OR advancing OR delaying) adj1 (rotation OR rotate OR rotating)).tw.
19. (rota OR roster OR duty OR shift OR shifts OR shiftwork OR hours OR week OR work).mp.
20. 18 and 19
21. 14 OR 15 OR 16 OR 17 OR 20
22. (randomized controlled trial OR controlled clinical trial).pt. OR randomized.ab. OR placebo.ab. OR drug therapy.fs. OR randomly.ab. OR trial.ab. OR groups.ab.
23. (effect* OR controll* OR control OR controls* OR controli* OR controle* OR controla* OR evaluation* OR program*).tw.
24. (work OR works* OR work* OR worka* OR worke* OR workg* OR worki* OR workl* OR occupation* or prevention* OR protect*).tw.
25. 24 and 23
26. (cohort OR cross sectional OR study OR survey OR questionnaire? OR diary OR diaries).tw.
27. Case-control studies/ OR cohort studies/ OR evaluation studies/ OR feasibility studies/ OR longitudinal studies/ OR program evaluation/ OR prospective studies/ OR retrospective studies/ OR exp follow-up studies/ OR exp risk Factors/ OR exp evaluation studies/ OR exp retrospective Studies OR exp chi-square distribution/ OR logistic models/ OR exp treatment outcome/ OR exp comparative studies OR cross-sectional studies/ OR multivariate analysis/
28. 22 OR 25 OR 26 OR 27
29. exp animals/ not humans.sh.
30. 28 NOT 29
31. 13 AND 21 AND 30

 

Appendix 2. EMBASE search strategy

1. ((work NEAR/2 hour*) OR (shift NEAR/2 work*) OR (work* NEAR/2 week) OR nightshift* OR shiftwork* OR (day NEAR/2 schedule))
2. ((rotat* NEAR/2 (backward OR forward OR rapid OR slow OR rapidly OR slowly OR advancing OR delaying)) AND (shift* OR work* OR schedule OR time OR duty OR hours OR rota OR roster))
3. (shift$ NEAR/1 (rota OR system$ OR schedul* OR hours OR time OR pattern* OR cycle OR extend* OR evening OR late OR roster OR early OR weekend OR twilight OR graveyard OR night$ OR split OR non-standard OR "non standard" OR flex$ OR turnaround OR continuous OR rotat*)
4. (shift* NEAR/2 (backward OR forward OR rapid OR slow OR rapidly OR slowly OR advancing OR delaying OR roster OR rota OR "day week"))
5. (nightshift* OR shiftwork*).tw. OR rota*?.tw. OR roster*.tw. OR 'day week'.tw.
6.exp Sleep Disorders/ OR 3. exp Circadian Rhythm/ OR exp "wounds and injuries"/ OR occupational injuries/ OR exp Death, Sudden, Cardiac/ OR Death, Sudden/ OR Death/ OR exp "costs and cost analysis"/ OR exp Chronobiology Disorders/
7. (sleep OR sleepiness OR circadian OR vigilance OR altertness OR alert OR wakefulness OR drowsiness OR fatigue OR insomnia OR hypersomnolence OR dyssomnia OR eveningness OR morningness OR "concentration difficulties" OR attentiveness OR arousal OR performance OR vigilant OR nap OR napping OR rest OR resting OR errors OR incidents OR accidents OR mistakes OR safety OR deaths OR death OR mortality OR injury OR injuries OR chronotherapy OR light OR daylight OR dark OR darkness OR econom$ OR cost OR costs).tw.
8. treatment outcome/ OR intermethod comparison/ OR major clinical study/ OR controlled study/ OR prospective study/ OR case-control study/ OR clinical article/ OR controlled study/ OR risk factor/ OR exp Follow Up/ OR outcomes research/ OR multivariate analysis/ OR retrospective study/ OR cohort analysis/ OR comparative study/ OR population research/ OR risk factors/
9. (cross adj1 sectional).tw OR compared.tw OR compares.tw. OR (cohort OR cross-sectional OR case-control OR study OR survey OR surveys OR diary OR diaries OR questionnaire? OR groups OR comparison$ OR multivariate OR risk factor$ OR effectiveness).mp.
10. 1 OR 2 OR 3 OR 4 OR 5
11. 6 OR 7
12. 8 OR 9
13. 10 AND 11 AND 12

 

Appendix 3. OPEN GREY

(((work NEAR/2 hour*) OR (shift NEAR/2 work*) OR (work* NEAR/2 week) OR nightshift* OR shiftwork* OR (day NEAR/2 schedule) OR ((rotat* NEAR/1 (backward OR forward OR rapid OR slow OR rapidly OR slowly OR advancing OR delaying) AND (shift* OR work* OR schedule OR time OR duty OR hours OR rota OR roster)) OR (shift$ NEAR/1 (rota OR system$ OR schedul* OR hours OR time OR pattern* OR cycle OR extend* OR evening OR late OR roster OR early OR weekend OR twilight OR graveyard OR night$ OR split OR non-standard OR "non standard" OR flex$ OR turnaround OR continuous OR rotat*)) OR (shift* NEAR/2 (backward OR forward OR rapid OR slow OR rapidly OR slowly OR advancing OR delaying OR roster OR rota OR “day week” )) AND (sleep OR sleepiness OR circadian OR vigilance OR altertness OR alert OR wakefulness OR drowsiness OR fatigue OR insomnia OR hypersomnolence OR dyssomnia OR eveningness OR morningness OR "neurocognitive performance" OR "concentration difficulties" OR attentiveness OR arousal OR performance OR vigilant OR nap OR napping OR rest OR resting OR errors OR incidents OR accidents OR mistakes OR safety OR deaths OR death OR mortality OR injury OR injuries OR chronotherapy OR light OR daylight OR dark OR darkness OR econom$ OR cost OR costs OR light OR dark OR darkness OR goggles OR exercise))

 

Appendix 4. PsycINFO

S1 TX ((work N2 hour*) OR (shift N2 work*) OR (work* N2 week) OR nightshift* OR shiftwork* OR (day N2 schedule))
S2 TX ((rotat* N2 (backward OR forward OR rapid OR slow OR rapidly OR slowly OR advancing OR delaying)) AND (shift* OR work* OR schedule OR time OR duty OR hours OR rota OR roster))
S3 TX (shift$ N2 (rota OR system$ OR schedul* OR hours OR time OR pattern* OR cycle OR extend* OR evening OR late OR roster OR early OR weekend OR twilight OR graveyard OR night$ OR split OR non-standard OR "non standard" OR flex$ OR turnaround OR continuous OR rotat*))
S4 TX (shift* N2 (backward OR forward OR rapid OR slow OR rapidly OR slowly OR advancing OR delaying) OR (roster OR rota) OR "day week")
S5 TX (sleep OR sleepiness OR circadian OR vigilance OR altertness OR alert OR wakefulness OR drowsiness OR fatigue OR insomnia OR hypersomnolence OR dyssomnia OR eveningness OR morningness OR "neurocognitive performance" OR "concentration difficulties" OR attentiveness OR arousal OR performance OR vigilant OR nap OR napping OR rest OR resting OR errors OR incidents OR accidents OR mistakes OR safety OR deaths OR death OR mortality OR injury OR injuries OR chronotherapy OR light OR daylight OR dark OR darkness OR econom$ OR cost OR costs)
S6 DE workday shifts
S7 DE human biological rhythms
S8 DE sleepiness
S9 DE sleep deprivation
S10 DE sleep disorders
S11 DE sleep
S12 DE physiological arousal
S13 DE fatigue
S14 DE workday shifts
S15 DE work scheduling
S16 DE performance
S17 DE occupational safety
S18 DE napping
S19 DE job performance
S20 DE wakefulness
S21 DE sleep onset
S22 DE mortality rate
S23 DE trends
S24 DE risk factors
S25 DE longitudinal studies
S26 DE follow up studies
S27 DE retrospective studies
S28 TX control OR (cross N1 sectional) OR compared OR compares OR cohort OR cross-sectional OR (case N1 control) OR study OR survey OR surveys OR diary OR diaries OR questionnaire? OR evaluation OR evaluate OR groups OR comparison$ OR multivariate OR risk factor$ OR effectiveness OR random* OR allocation OR allocate OR allocated
S29 S28 OR S27 OR S26 OR S25 OR S24 OR S23
S30 S22 OR S21 OR S20 OR S19 OR S18 OR S17 OR S16 OR S13 OR S12 OR S11 OR S10 OR S9 OR S8 OR S7 OR S5
S31 S1 OR S2 OR S3 OR S4 OR S6 OR S15
S32 S31 AND S30 AND S29

 

Appendix 5. Web of Knowledge

  1. TS=(work NEAR/2 hour*)
  2. TS=(shift NEAR/2 work*)
  3. TS=(work* NEAR/2 week)
  4. TS=(nightshift* OR shiftwork*)
  5. TS=(day NEAR/2 schedule*)
  6. TS=(rotat* NEAR/1 (backward OR forward OR rapid OR slow OR rapidly OR slowly OR advancing OR delaying))
  7. TS=(shift* OR work* OR schedule OR time OR duty OR hours OR rota OR roster)
  8. #6 AND #7
  9. TS=(shift$ NEAR/1 (rota OR system$ OR schedul* OR hours OR time OR pattern* OR cycle OR extend* OR evening OR late OR roster OR early OR weekend OR twilight OR graveyard OR night$ OR split OR non-standard OR "non standard" OR flex$ OR turnaround OR continuous OR rotat*))
  10. TS=(roster OR rota)
  11. TS=("day week")
  12. TS=(shift* NEAR/1 (backward OR forward OR rapid OR slow OR rapidly OR slowly OR advancing OR delaying))
  13. TS=(sleep OR sleepiness OR circadian OR vigilance OR altertness OR alert OR wakefulness OR drowsiness OR fatigue OR insomnia OR hypersomnolence OR dyssomnia OR eveningness OR morningness OR "neurocognitive performance" OR "concentration difficulties" OR attentiveness OR arousal OR performance OR vigilant OR nap OR napping OR rest OR resting OR errors OR incidents OR accidents OR mistakes OR safety OR deaths OR death OR mortality OR injury OR injuries OR chronotherapy OR light OR daylight OR dark OR darkness OR econom$ OR cost OR costs)
  14. TS=(effect* OR controll* OR control OR controls* OR controli* OR controle* OR controla* OR evaluation* OR program* OR cohort OR cross sectional OR study OR survey OR questionnaire? OR diary OR diaries OR placebo OR random* OR trial OR groups OR multivariate OR compare? OR comparison* OR risk factor?)
  15. #1 OR #2 OR #3 OR #4 OR #5 OR #8 OR #9 OR #10 OR #11 OR #12#15 AND #14 AND #13
  16. TI=(mice OR rats)
  17. #15 NOT #16

 

Appendix 6. Cochrane CENTRAL

#1 ((work NEAR/2 hour*) OR (shift NEAR/2 work*) OR (work* NEAR/2 week) OR nightshift* OR shiftwork* OR (day NEAR/2 schedule)):kw
#2 ((rotat* NEAR/2 (backward OR forward OR rapid OR slow OR rapidly OR slowly OR advancing OR delaying)) AND (shift* OR work* OR schedule OR time OR duty OR hours OR rota OR roster)):kw
#3 (shift$ NEAR/2 (rota OR system$ OR schedul* OR hours OR time OR pattern* OR cycle OR extend* OR evening OR late OR roster OR early OR weekend OR twilight OR graveyard OR night$ OR split OR non-standard OR "non standard" OR flex$ OR turnaround OR continuous OR rotat*)):kw
#4 (shift* NEAR/2 (backward OR forward OR rapid OR slow OR rapidly OR slowly OR advancing OR delaying) OR (roster OR rota) OR "day week"):kw
#5 MeSH descriptOR Work Schedule Tolerance explode all trees
#6 (sleep OR sleepiness OR circadian OR vigilance OR altertness OR alert OR wakefulness OR drowsiness OR fatigue OR insomnia OR hypersomnolence OR dyssomnia OR eveningness OR morningness OR "neurocognitive performance" OR "concentration difficulties" OR attentiveness OR arousal OR performance OR vigilant OR nap OR napping OR rest OR resting OR errors OR incidents OR accidents OR mistakes OR safety OR deaths OR death OR mortality OR injury OR injuries OR chronotherapy OR light OR daylight OR dark OR darkness OR econom$ OR cost OR costs):kw
#7 MeSH descriptor Sleep Phase Chronotherapy explode all trees
#8 MeSH descriptor Chronotherapy explode all trees
#9 MeSH descriptor Chronobiology Disorders explode all trees
#10 MeSH descriptor Sleep Disorders, Circadian Rhythm explode all trees
#11 MeSH descriptor Dyssomnias explode all tree
#12 MeSH descriptor Sleep Disorders, Circadian Rhythm explode all trees
#13 MeSH descriptor Sleep Initiation and Maintenance Disorders explode all trees
#14 MeSH descriptor Sleep Deprivation explode all trees
#15 MeSH descriptor Sleep Disorders, Intrinsic explode all trees
#16 MeSH descriptor Sleep Disorders explode all trees
#17 MeSH descriptor Sleep explode all trees
#18 MeSH descriptor Psychomotor Performance explode all trees
#19 MeSH descriptor Medical Errors explode all trees
#20 MeSH descriptor Mortality explode all trees
#21 MeSH descriptor Death explode all trees
#22 MeSH descriptor Wounds and Injuries explode all trees
#23 MeSH descriptor Fatigue explode all trees
#24 MeSH descriptor Economics explode all trees
#25 MeSH descriptor Cost of Illness explode all trees
#26 (#1 OR #2 OR #3 OR #4 OR #5)
#27 (#6 OR #7 OR #8 OR #9 OR #10 OR #11 OR #12 OR #13 OR #14 OR #15 OR #16 OR #17 OR #18 OR #19 OR #20 OR #21 OR #22 OR #23 OR #24 OR #25)
#28 (#26 AND #27)

 

Contributions of authors

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Acknowledgements
  6. Appendices
  7. Contributions of authors
  8. Declarations of interest

Christine Herbst: drafting of the protocol including introduction, methodology and search strategies, proofreading.

Thomas C Erren: advice for all sections of the protocol, proofreading.

Mikael Sallinen: definitions of outcomes, proofreading.

Lin E Fritschi: methodological advice, definitions of outcomes, proofreading.

Giovanni Costa: proofreading.

Tim R Driscoll: methodological advice, proofreading.

Russell G Foster: proofreading.

Melissa S Koch: proofreading.

Juha Liira: organisation of the combined protocol which was split into several topics, proofreading.

 

Declarations of interest

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Acknowledgements
  6. Appendices
  7. Contributions of authors
  8. Declarations of interest

Christine Herbst: Organisation and preparation of the review is one of her duties as a research assistant at the Institute and Policlinic for Occupational Medicine, Environmental Medicine and Prevention Research, University Clinic of Cologne, University Hospital of Cologne, Cologne, Germany

Thomas C Erren: none known

Mikael Sallinen: a grant outside the scope of the submittted work

Lin E Fritschi:none known

Giovanni Costa: none known.

Tim R Driscoll: none known.

Russell G Foster: His institution currently receives a grant from the Wellcome Trust "Melanopsin signalling: phototransduction, behavioural regulation and clinical relevance" Start date: 1st June 2010 for 5 years. He receives royalties from a book "Rhythms of Life: The biological clocks that control the daily lives of every living thing" and is employed for by the University of Oxford. He is a board member of the Biotechnology and Biological Sciences Research Council.

Melissa S Koch: none known.

Juha Liira: He has received the following payments linked to work on occupational health and work places: Ilmarinen (insurance company) 12000 euros for a total of five lectures on well-being at work; Research Council of Norway 1500 euros for reviewing applications submitted to the PETROMAKS research.

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  2. Abstract
  3. Background
  4. Objectives
  5. Methods
  6. Acknowledgements
  7. Appendices
  8. Contributions of authors
  9. Declarations of interest
  10. Additional references
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