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INSOMNIA SEVERITY INDEX

  1. Top of page
  2. INSOMNIA SEVERITY INDEX
  3. MEDICAL OUTCOMES STUDY (MOS) SLEEP SCALE
  4. PITTSBURGH SLEEP DIARY
  5. PITTSBURGH SLEEP QUALITY INDEX (PSQI)
  6. References
  7. Supporting Information

General Description

Purpose.

The Insomnia Severity Index (ISI) is designed to be both a brief screening measure of insomnia and an outcomes measure for use in treatment research (1,2).

Content.

Scale content corresponds in part to DSM-IV criteria for insomnia, and measures the subject's current (within the past 2 weeks) perception of symptom severity, distress, and daytime impairment. Items include: the severity of sleep onset and maintenance (middle and early morning awakening) difficulties, satisfaction with current sleep pattern, interference with daily functioning, appearance of impairment attributed to the sleep problem, and the degree of concern caused by insomnia.

Developer/contact information.

Charles M. Morin, PhD. E-mail: .

Versions.

Primary version is self-administered; clinician-administered, significant other, and French language versions are available.

Number of items in scale.

There are 7 items.

Subscales.

None.

Population.
Developmental/target.

The psychometric properties of ISI were reported from a sample of adults (ages 17–84 years) with insomnia complaints (primary and secondary to medical, psychiatric, or other sleep disorders) (2).

Other uses.

The ISI has also been validated on samples of young adults (mean age 20 years) (3), and older adults (mean age 65 years) with primary insomnia (2).

WHO ICF Components.

Body function, Impairment, Activity limitation, Participation restriction, Environmental factor.

Administration

Method.

Self-administration; paper and pencil.

Training.

Minimal.

Time to administer/complete.

Five minutes or less.

Equipment needed.

None.

Cost/availability.

No cost; available from authors. Copy available at the Arthritis Care & Research Web site at http://www.interscience.wiley.com/jpages/0004-3591:1/suppmat/index.html.

Scoring

Responses.
Scale.

Five-point Likert scale (0 = not at all, 4 = extremely).

Score range.

Range is 0–28.

Interpretation of scores.

Suggested guidelines for interpretation: 0–7 = no clinically significant insomnia; 8–14 = subthreshold insomnia; 15–21 = clinical insomnia of moderate severity; 21–28 = severe clinical insomnia. Guidelines require additional validation. Smith and Trinder (3) found a cutoff score of 14 distinguished subjects with insomnia from normal controls with a sensitivity = 94% and specificity = 94%.

Method of scoring.

Individual items are summed by hand.

Time to score.

Less than one minute.

Training to score.

Minimal.

Training to interpret.

Minimal.

Norms available.

Traditional norms are not available. Mean (SD) for insomnia patients (n = 145) is 19.7 (4.1). Mean (SD) older adults with DSM-IV diagnosis of primary insomnia is 15.4 (4.2). ISI scores for the 5 insomnia subgroups in the original sample were pain conditions (20.2); psychophysiological (19.5); psychiatric (21.0); idiopathic (19.7); alcohol/substance abuse (19.8); and other (19.5) (2).

Psychometric Information

Reliability.
Internal consistency.

Cronbach's alpha = 0.74 to 0.78. Individual item correlations to the total score ranged from 0.36 (difficulty falling asleep) to 0.67 (interference with daily functioning), with a mean of 0.54. Internal reliability coefficients of individual items to total score demonstrated increased stability following treatment with means of 0.69 at post-treatment and 0.72 at followup (2).

Validity.
Content.

The ISI has good face validity with the concept of insomnia as defined by DSM-IV. Formal evaluation of content validity was demonstrated via principal component analysis, which yielded 3 components (impact, severity, and satisfaction). These components are consistent with the diagnostic criteria of insomnia and captured 72% of the variance (2).

Criterion.

A cutoff score of 14 demonstrated a sensitivity of 94% and a specificity of 94% in distinguishing individuals diagnosed with primary insomnia from good sleeper controls. Diagnoses were established based on integration of expert clinical interview, polysomnography, and psychometric testing (3).

Concurrent.

Bastien and colleagues reported significant correlations of select ISI items and Total Score with relevant polysomnography (PSG) variables before and after treatment (2). The ISI Sleep Onset item was the only significant pretreatment correlation (r = 0.45; P < 0.05, PSG Sleep Latency). At posttreatment, ISI Total Score correlated with PSG Sleep Efficiency (−0.35; P < 0.05). ISI Sleep Onset and middle insomnia items correlated with PSG Sleep Latency and Wake After Sleep Onset (0.39 and 0.45; P < 0.05, respectively).

In regards to sleep diatries, Bastien and colleagues (2) reported significant correlations of select ISI items with corresponding daily sleep diary parameters in 2 separate samples, one of which included correlations between measures both before and after treatment. Pretreatment correlations were weak to moderate (0.32–0.55) and posttreatment correlations were moderate to strong (0.55–0.99). The ISI Total Score correlated weakly to moderately with diary measures of Sleep Efficiency (Pearson's r values ranging between −0.19 and −0.61).

Correlation coefficients between clinician ISI ratings and the patient version for ISI total score ranged between 0.57 and 0.71, P < 0.01. Individual item correlations between the 2 versions ranged between 0.50 (difficulty staying asleep) and 0.69 (problem waking up too early).

Predictive.

Clinician ratings of insomnia severity predicted ISI Total Score. R2 ranged from 0.37 (pretreatment) to 0.61 (post-treatment) P < 0.05) (2).

Sensitivity/responsiveness to change.

Morin and colleagues demonstrated sensitivity to change following pharmacologic and/or behavioral intervention for primary insomnia in older adults (4).

Comments and Critique

The ISI is a face valid index of insomnia severity demonstrating criterion validity and other adequate psychometric properties. It has been validated against both polysomnographic and prospective sleep diary measures and demonstrates convergence with clinical interview criteria. It may be particularly useful for treatment outcome research in which insomnia is a secondary endpoint, and a brief, low subject burden instrument is needed. It may also be useful for diagnosis and treatment planning. The cutoff score may be useful as a guideline for clinicians in evaluating the clinical significance of the insomnia complaint. While not specifically developed for rheumatology patients, scale development included a heterogenous group of patients with insomnia secondary to pain conditions.

Due to its brevity and Likert scale data, this instrument would not be an appropriate stand-alone measure of sleep disturbance. The scale is limited to questions pertaining to insomnia severity/impact and does not assess frequency of symptoms. It also does not include items relevant to other sleep disorders, which may occur more frequently in chronic pain populations (e.g., periodic limb movements, restless legs syndrome, or sleep apnea). More research demonstrating the psychometric properties of the ISI, and establishing cutoff scores and sensitivity to change in rheumatologic populations is needed.

References

1. (Original) Morin CM. Insomnia: psychological assessment and management. New York: Guilford Press; 1993.

2. Bastien CH, Vallie'res A, Morin CM. Validation of the Insomnia Severity Index as an outcome measure for insomnia research. Sleep Med 2000;2:297–307.

3. Smith S, Trinder J. Detecting insomnia: comparison of four self-report measures of sleep in a young adult population. J Sleep Res 2001;10:229–35.

4. Morin CM, Colecchi C, Stone J, Sood R, Brink D. Behavioral and pharmacological therapies for late-life insomnia: a randomized controlled trial. JAMA 1999;281:991–9.

MEDICAL OUTCOMES STUDY (MOS) SLEEP SCALE

  1. Top of page
  2. INSOMNIA SEVERITY INDEX
  3. MEDICAL OUTCOMES STUDY (MOS) SLEEP SCALE
  4. PITTSBURGH SLEEP DIARY
  5. PITTSBURGH SLEEP QUALITY INDEX (PSQI)
  6. References
  7. Supporting Information

General Description

Purpose.

Measure 6 sleep dimensions. The sleep scale is one subscale of the Medical Outcomes Study (MOS) health status measure (1).

Content.

Consists of 12 items to measure 6 sleep dimensions: initiation (time to fall asleep), quantity (hours of sleep each night), maintenance, respiratory problems, perceived adequacy, somnolence (the last 4 items reported using a 6-item Likert scale ranging from “All of the time” to “None of the time”). The time frame for the responses is “the past 4 weeks.”

Developer/contact information.

RD Hays and AL Stewart, Medical Outcomes Trust, 198 Tremont Street #503, Boston, MA 02166. Available at http://www.outcomes-trust.org/instruments.htm.

Versions.

A 6-item Likert-scale short form is available that measures initiation, maintenance, respiratory problems, adequacy, and somnolence. A correlation of 0.97 indicates the short version is nearly equivalent to the long version.

Number of items in scale.

There are 12 items.

Subscales.

Two indexes can be derived: Sleep Problems Index I (short form) and Sleep Problems Index II (long form). Additional subscales can be derived: sleep disturbance, snoring, sleep shortness of breath or headache, sleep adequacy, sleep somnolence, sleep quantity, and optimal sleep.

Populations.
Developmental/target.

Patients served in primary care and multi-specialty practices.

Other uses.

Has been used with congestive heart failure, patients with depression, diabetes, recent myocardial infarction, hypertension, asthma, back problems, arthritis samples.

WHO ICF Components.

Body function, Impairment, Activity limitation, Participation restriction.

Administration

Method.

Self-report instrument that may be administered in person, by mail, or telephone.

Training.

No training needed.

Time to administer/complete.

Not reported. Estimated to be 2–3 minutes for 12 items.

Equipment needed.

None, other than instrument and writing implement.

Cost/availability.

No cost. Available through source listed above and references listed below.

Scoring

Responses.
Scale.

Sleep Initiation (0–15 minutes, 16–30 minutes, 31–45 minutes, 46–60 minutes, 60+ minutes); Sleep Quantity (number of hours), 10 items about other sleep activities (All of the Time, Most of the Time, A Good Bit of the Time, Some of the Time, A Little of the Time, None of the Time).

Score range.

The range for the 12-item version is 12–71.

Interpretation of scores.

No formal cutoff scores are provided. Data from original scale development samples are available for comparison.

Method of scoring.

Scoring is done by hand, requires reverse scoring of selected items and only requires simple arithmetic.

Time to score.

Less than 5 minutes.

Training to score.

Training is minimal.

Training to interpret.

Training is minimal.

Norms available.

No formal norms have been published. Data from original scale development samples are available for comparison.

Psychometric Information

Reliability.
Internal consistency.

Cronbach alpha ranged from 0.75 to 0.86 for item to subscales. Item-total correlations were 0.03–0.64, which is not surprising given the multiple dimensions of sleep assessed. Intercorrelations among subscales ranged from 0.05 to 0.88.

Test-retest.

Not available.

Intra/interrater.

Not formally reported or applicable; self-report data with objective, simple scoring.

Variability.

Full range of scores observed with fairly normal distribution (skewness ranging from −0.055 to 1.81 for items).

Validity.
Content.

The MOS has good face validity covering multiple dimensions of sleep that are represented in prior sleep measures.

Criterion.

The MOS has not been formally compared to sleep laboratory observations.

Concurrent/predictive.

Not available.

Construct/discriminant.

Comparison of the MOS Sleep scale with other dimensions of the MOS indicated correlations in the expected directions (Effects of pain 0.53, Pain severity 0.44, Physical symptoms 0.57, Energy/fatigue −0.60, Physical functioning −0.36, Cognitive functioning −0.53, Depression/behavioral-emotional control 0.57, Anxiety 0.57, Positive affect −0.55).

Sensitivity/responsiveness to change.

Not established.

Comments and Critique

The MOS is a face valid index of sleep disturbance with adequate established reliability but no established validity with objective sleep measures. It should be noted that the subscales do not necessarily reflect DSM criteria for insomnia diagnosis. Criterion validity remains to be established and comparison with other sleep measures is unknown. The lack of a cutoff score undermines its utility as a clinical tool. Other sleep measures have more established validity and would be more appropriate for research focused on sleep parameters. While not specifically normed on a rheumatology sample, as it was developed using a large number of patients served in primary care and specialty practice settings, the MOS is one of the few health status measures that has a sleep subscale. The MOS scale may be more useful in studies where the focus is general health status assessment but information on sleep parameters is of interest. The short 6-item version is nearly equivalent to the 12-item version and reduces subject burden. It should be noted there is no item assessing use of sleep medication or assessment of leg movements, if these are variables of interest. The sleep somnolence subscale actually measures daytime sleepiness. The utility in treatment outcome studies remains to be established. It should be noted, while the Short Form-36 is a brief version of the MOS it does not contain items on sleep behavior.

Reference

1. (Original) Stewart AL, Ware JE, Brook RH, Davies AR. Conceptualization and measurement of health for adults in the Health Insurance Study. Vol II. Physical health in terms of functioning. Santa Monica (CA): The RAND Corporation; 1978. p. 236–359.

Additional References

Hays RD, Stewart AL. Sleep measures. In: Stewart AL, Ware JE, editors. Measuring functioning and well-being: the Medical Outcomes Study Approach. Durham (NC): Duke University Press; 1992. p. 235–59.

Stewart AL, Hays RD, Ware JE. The MOS Short-Form General Health Survey: reliability and validity in a patient population. Med Care 1988;26:724–732.

PITTSBURGH SLEEP DIARY

  1. Top of page
  2. INSOMNIA SEVERITY INDEX
  3. MEDICAL OUTCOMES STUDY (MOS) SLEEP SCALE
  4. PITTSBURGH SLEEP DIARY
  5. PITTSBURGH SLEEP QUALITY INDEX (PSQI)
  6. References
  7. Supporting Information

General Description

Purpose.

The Pittsburgh Sleep Diary (PSD) is designed to quantify subjectively reported sleep and waking behaviors for use in research and practice (1).

Content.

The PSD is organized into 2 daily questionnaires completed at “bedtime” and “waketime.” The bedtime questionnaire gathers data on 1) the timing of meals; 2) consumption of caffeine, alcohol, and tobacco products; 3) medication use; and 4) and the timing and duration of exercise and nap periods. The waketime questionnaire gathers data on 1) bedtime; 2) “lights out time;” 3) sleep latency (SL); 4) final waketime; 5) method of final awakening; 6) frequency of nightly awakenings (FNA); 7) wake after sleep onset time (WASO); 8) reason for nightly awakenings, 9) sleep quality; and 10) mood on final wakening, and alertness on final wakening.

Developer/contact information.

Timothy H. Monk, PhD, Sleep and Chronobiology Center Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, 3811 O'Hara Street, Pittsburgh, PA 15213. Fax: 1-412-624-2841.

Versions.

Multiple versions of sleep diaries have been developed (2–4). The PSD was selected for review because it is the most comprehensive published diary with psychometric data.

Number of items in scale.

The bedtime questionnaire is comprised of 6 general items. The waketime questionnaire is comprised of 11 general items.

Subscales.

None.

Populations.
Developmental/target.

The PSD was developed from 3 investigations including samples of sleep disorder patients (n = 28) and healthy adult controls (young [n = 29], middle-aged [n = 96], and older adult [n = 81]). Sleep disorder patients included patients with insomnia or hypersomnia.

Other uses.

Similar sleep diaries have been used to assess sleep parameters in heterogeneous chronic pain patients (3,5,6) and fibromyalgia (7). Sleep diaries are extensively used in the clinical trials literature of insomnia (8–10). Diaries have also been found to be useful in evaluating circadian rhythm disorders (11).

WHO ICF Components.

Body function, Impairment, Environmental factor.

Administration

Method.

Questionnaire, paper and pencil (electronic and mail versions have been developed). Standard assessment periods of 1 week, and more preferably 2 weeks, are recommended to account for night-to-night variability in sleep disorder populations. Compliance problems need to be considered (12). Electronic versions can be adopted for use with PDA handheld devices. Electronic delivery enhances data integrity with audible reminder features, and time and date stamping of entries (7).

Training.

Brief training of subjects is required to avoid missing values and erroneous data. Subjects should be instructed to keep the diary on their nightstand with a pen or pencil available. The nighttime questionnaire is to be completed immediately before retiring to bed. The morning questionnaire is to be completed shortly after waking. Instruction is required on properly estimating wake after sleep onset time and the use of visual analog scales. Individuals complete both questionnaires each day for a period of 1 to 2 weeks or longer.

Time to administer/complete.

Ten minutes a day (5 minutes for the bedtime questionnaire and 5 minutes for the waketime questionnaire).

Equipment needed.

None.

Cost, availability.

No cost; available from authors. Copy available at the Arthritis Care & Research Web site at http://www.interscience.wiley.com/jpages/0004-3591:1/suppmat/index.html.

Scoring

Responses.
Scale.

The timing (hour:minutes) and duration (minutes) of various daytime and sleep-wake parameters and activities are hand entered. For the nighttime questionnaire, the frequency of servings of caffeine, alcohol, and tobacco products are indicated for 4 time periods: 1) before or with breakfast; 2) after breakfast, before/with lunch; 3) after lunch before/with dinner; and 4) after dinner. Name, timing, and dosage of medications are hand entered. For the waketime questionnaire, subjects indicate the timing of bedtime and final waketime, and the duration of sleep latency and wake after sleep onset time. Subjects also check on a categorical scale the method of final awakening: “alarm/clock radio,” “someone whom I asked to wake me,” “noises,” or “just woke.” Frequency of nightly awakenings is indicated using a 6-point Likert scale: 0–5 or more. Frequency of awakenings to use the bathroom, awakenings by noise/bedpartner, awakenings due to physical discomfort, and spontaneous awakenings are indicated on the same 6-point Likert scale. Ratings of sleep quality, mood on final wakening, and alertness are made on 100-mm visual analog scales.

Score range.

In addition to categorical and frequency data generated by the nighttime questionnaire, the waketime questionnaire permits the calculation of standard continuity parameters as follows: 1) Sleep latency (SL), minutes; ranges from 0 to total time in bed (TIB); 2) frequency of nightly awakenings (FNA); ranges from 0 to 5+; 3) wake after sleep onset time (WASO), minutes; ranges from 0 to TIB – SL; 4) total sleep time (TST), minutes calculated by the formula, TST= [TIB – (SL+WASO)]; ranges from 0 to TIB; 5) Sleep efficiency percentage (SE), calculated by formula, SE = TST/TIB. Visual analog scales of sleep quality, mood, and alertness on waking range from 0 to 100 mm.

Interpretation of scores.

There are no formally established research diagnostic criteria for sleep diary estimates of sleep continuity. Commonly used clinical and research criteria for symptom severity are as follows: mean SL and/or WASO >30 minutes, mean SE <85% (2). Due to individual variation in TST, researchers are less inclined to establish TST criteria. Commonly used criteria for problem frequency is: ≥3 nights per week (2) for a 1-month period (13).

Method of scoring.

Scoring is done by hand. Calculation of previously described sleep continuity parameters can be easily automated. A ruler is required to measure the visual analog scales. Typically, mean values for each sleep parameter are obtained (averaged over 1 to 2 weeks).

Time to score.

Scoring time depends on the number of days data are collected. A week's worth of entries can usually be manually scored in 10–15 minutes.

Training to score.

Minimal.

Training to interpret.

Minimal.

Norms available.

Traditional norms are unavailable. Table 1 shows diary-based means and standard deviations that have been culled from the literature for reference.

Table 1. Sleep Diary Estimates of Sleep Continuity Parameters*
GroupsSLFNAWASOTSTSE%
  • *

    Values are mean (SD). SL = sleep latency; FNA = frequency of nightly awakenings; WASO = wake after sleep onset time; TST = total sleep time; SE% = sleep efficiency percentage; NR = not rated.

  • Based on meta-analysis of clinical trials literature of primary insomnia. Values are pretreatment means. Number of subjects included in averages varied due to differential reporting of sleep parameters by study. Results are based on a total of 23 clinical trials.

Healthy young adults, ages 20–30 years (n = 29), 41% female (1)10.7 (7.0)0.3 (0.5)6.7 (11.7)NRNR
Healthy older adult females, ages ≥81 years (n = 44) (1)24.3 (25.4)1.2 (0.7)23.4 (24.7)NRNR
Healthy older adult males, ages ≥81 years (n = 37) (1)15.7 (21.3)1.5 (0.8)21.8 (21.0)NRNR
General sleep disorder patients, (n = 28, 14 insomnia and 14 hypersomnia), 40% female (1)NRNR35.3 (33.2)NRNR
Mixed outpatient chronic pain, mean age 43 (10), 67% female (5)43.9 (22.3)2.26 (1.2)41.8 (40.9)391.4 (74.3)71.0 (14.0)
Chronic persistent insomnia, adults age range 18–80+, years, Mean n = 217, 65% female (8)51.5 (29.1)2.7 (1.9)61.8 (39.0)332.7 (46.6)NR

Psychometric Information

Reliability.

Reliability and validity data are primarily available for the waketime questionnaire sleep continuity and quality items.

Test-retest reliability.

Monk et al reported significant (P < 0.001) long-term test-retest correlation coefficients (r) for select waketime questionnaire variables with a mean intertest interval of 22 months (range 12–30 months): FNA = 0.67; WASO = 0.56; Sleep Quality = 0.59; Mood on waking = 0.61; Alertness on waking = 0.65; bedtime = 0.81; Lights out = 0.80; and Final waketime = 0.66 (1).

Short-term test-retest reliability.

Using a sleep diary similar to the waketime PSD items, Coates et al reported test-retest reliability coefficients measured over 3 consecutive days for poor sleepers of 0.93, 0.88, 0.84 for SL, FNA, and WASO, respectively (Spearman-Brown Prophecy coefficients) (14). For good sleepers, Coates et al reported coefficients of 0.81, 0.84 and 0.64 for SL, FNA, and WASO, respectively (14).

Inpatient chronic pain patients.

Haythornthwaite and colleagues used ordinally scaled diary items over a 4-day period (3). They reported internal consistency estimates for standard sleep continuity/quality questions (average interitem correlations using Fisher's Z transformation ranging from 0.41 (Sleep Quality) to 0.62 (TST). Spearman's Brown prophesy formula reliability test-retest coefficients ranged from 0.74 (Sleep Quality) to 0.87 (SL).

Validity.
Criterion.

Several investigations comparing sleep diary data against traditionally scored polysomnographic criteria have found patients with insomnia to reliably overestimate SL and WASO and underestimate TST compared with PSG (14,15). Diary estimates, however, have consistently been demonstrated to provide a valid relative index of insomnia. In a study of 122 men and women with chronic insomnia, Carskadon reported significant correlation coefficients between diary and PSG measures of SL (0.62) and TST (0.47), (P < 0.001, WASO not reported). Coates and colleagues reported a correlation coefficient of 0.98 for SL and 0.88 for WASO for a sample of 12 patients with insomnia, P < 0.01. Diaries have not been shown to be a valid indicator of Frequency of Nightly Awakenings (FNA).

Monk and colleagues reported PSD to be sensitive to significant age related differences in sleep continuity that were simultaneously verified by polysomnography (1). Specifically, the PSD found older adults to report longer WASO compared with young, good-sleeper control subjects (P < 0.0001). Longer WASO for the adult sample was confirmed via PSG. The authors did not report correlation coefficients.

Comparison with actigraphy.

Actigraphs are a lightweight, watch-like accelerometer device worn on the wrist, which are increasingly being used in sleep research to provide objective estimates of circadian rhythm (16), and sleep continuity (17,18). Algorithms for scoring sleep continuity parameters based on movement counts have been developed and validated against PSG, although more validation studies particularly for sleep disorder populations are needed (19). Monk et al reported the PSD correlated significantly with actigraphic measures of TST (r = 0.43, P < 0.0001) (1). They also reported PSD estimates of sleep disruption based on WASO were significantly related to mean activity counts between bedtime and waketime (t = 4.1, P < 0.0001).

Convergent.

Monk reported convergent validity with circadian type and personality measures. With respect to circadian type, PSD correlated in the expected direction on the morningness score of the Horne-Osteberg morningness questionnaire (P < 0.05). Specific PSD correlations with the morningness score were as follows: all PSD items pertaining to the timing of the sleep episode, rho > 0.6; ratings of alertness on awakening, rho = 0.35; and mood upon wakening, rho = 0.22. With respect to personality, elevated scores on neuroticism as measured by the Eysenck Personality Inventory were associated with PSD estimates of WASO (rho = 0.28), FNA (rho = 0.33), poorer sleep quality (rho = −0.34), negative mood (rho = −0.35), and decreased morning alertness (rho = −0.23) (P > 0.03).

Haythornthwaite and colleagues also reported convergent validity of a sleep diary in an inpatient sample of chronic pain patients. Diary measures correlated in the expected direction with standard measures of pain severity, depression, and anxiety (3).

Convergent validity with retrospective measures of sleep quality.

Monk et al reported small, but significant correlation of PSD items with the Pittsburgh Sleep Quality Index Global Score as follows: FNA rho = 32, P < 0.002; WASO rho = 0.27, P < 0.01; Sleep Quality rho = −0.36, P < 0.0005); Mood rho = −0.37, P < 0.0005; Alertness rho = −0.37, P < 0.0005 (1).

In chronic pain patients, Haythornthwaite et al. reported moderate correlations in the expected direction with their sleep diary and retrospective summary measures of sleep (coefficient ranged from 0.31 to 0.48, P < 0.05) (3).

Sensitivity/responsiveness to change.

Sleep diaries are the most widely used outcome metric in both the behavioral and pharmacologic clinical trials literatures of insomnia (8). Numerous studies and meta-analyses have demonstrated excellent sensitivity to change (9,20–22). Notably, sleep diary measures have been shown to detect treatment effects for cognitive-behavioral therapy for insomnia secondary to chronic pain. These effects were concurrently validated via actigraphy (23).

Comments and Critique

Sleep diaries are a valuable tool in sleep research to quantify subjective sleep disturbance. In rheumatology and pain research, however, sleep diaries have been used infrequently. Most clinical trials of chronic pain have relied on brief retrospective ratings of sleep quality with dubious validity. This is somewhat surprising given that pain diaries have become an important instrument in the assessment of chronic pain conditions. Standard sleep continuity/quality items can easily be added to pain diaries. Electronic diaries with data integrity features and automatic scoring capability will undoubtedly increase their use in pain research.

Prospective diary monitoring has distinct advantages over retrospective measures in its sensitivity to variations in sleep parameters over time and its diminished vulnerability to recall bias. Compared to traditional PSG, they permit a relatively unobtrusive, inexpensive assessment of sleep quality in the natural environment.

Concern that sleep diaries overestimate insomnia severity relative to objective measures of sleep, should be considered by researchers utilizing only one measure of sleep disturbance. However, despite reliable deviations from polysomnographic measures, diaries have been found to yield a valid, relative index of insomnia, which is sensitive to change. Furthermore, recent studies analyzing sleep microstructure have found that patients reporting the largest discrepancies between sleep diary and PSG show a heightened degree of fast-frequency electroencephalogram activity during non-rapid eye movement sleep (24,25). This research suggests that subjective estimates of sleep quality may actually reflect a combination of traditional sleep continuity disturbance measures and sleep microstructure abnormalities. The findings highlight the need for a multi-method approach to sleep assessment that combines, subjective ratings and objective measures such as PSG and actigraphy. Finally, although sleep diaries rarely have formal weekday (work week) and weekend (days off) subscales, these factors should be considered in the interpretation of any sleep diary data.

References

1. (Original) Monk TH, Reynolds CF, Kupfer DJ, Buysse DJ, Coble PA, Hayes AJ, et al. The Pittsburgh Sleep Diary. J Sleep Res 1994;3:111–20.

2. Morin CM. Insomnia: psychological assessment and management. New York: Guilford Press; 1993.

3. Haythornthwaite JA, Hegel MT, Kerns RD. Development of a sleep diary for chronic pain patients. J Pain Symptom Manage 1991;6:65–72.

4. Akerstedt T, Hume K, Minors D, Waterhouse J. The subjective meaning of good sleep, an intraindividual approach using the Karolinska Sleep Diary. Percept Mot Skills 1994;79:287–96.

5. Smith MT, Perlis ML, Smith MS, Giles DE. Pre-sleep cognitions in patients with insomnia secondary to chronic pain. J Behav Med 2001;24:93–-114.

6. Wilson KG, Watson ST, Currie SR. Daily diary and ambulatory activity monitoring of sleep in patients with insomnia associated with chronic musculoskeletal pain. Pain 1998;75:75–84.

7. Affleck G, Urrows S, Tennen H, Higgins P, Abeles M. Sequential daily relations of sleep, pain intensity, and attention to pain among women with fibromyalgia. Pain 1996;68:363–8.

8. Smith MT, Perlis ML, Park A, Smith MS, Pennington JY, Giles DE, et al. Comparative meta-analysis of pharmacotherapy and behavior therapy for persistent insomnia. Am J Psychiatry 2002;159:5–11.

9. Edinger JD, Wohlgemuth WK, Radtke RA, Marsh GR, Quillian RE. Cognitive behavioral therapy for treatment of chronic primary insomnia: a randomized controlled trial. JAMA 2001;285:1856–64.

10. Morin CM, Colecchi C, Stone J, Sood R, Brink D. Behavioral and pharmacological therapies for late-life insomnia: a randomized controlled trial. JAMA 1999;281:991–9.

11. Harma M, Sallinen M, Ranta R, Mutanen P, Muller K. The effect of an irregular shift system on sleepiness at work in train drivers and railway traffic controllers. J Sleep Res 2002;11:141–51.

12. Stone AA, Shiffman S, Schwartz JE, Broderick JE, Hufford MR. Patient non-compliance with paper diaries. BMJ 2002;324:1193–4.

13. American Psychiatric Association. Diagnositic and Statistical Manual of Mental Disorders (DSM-IV). 4 ed. Washington (DC): American Psychiatric Association; 1994.

14. Coates TJ, Killen J, George J, Marchini E, Hamilton S, Thoresen C. Estimating sleep parameters: a multitrait-multimethod analysis. J Consult Clin Psychol 1982;50:345–52.

15. Carskadon M, Dement W, Mitler M, Guilleminault C, Zarcone VP, Spiegel R. Self-reports versus sleep laboratory findings in 122 drug-free subjects with complaints of chronic insomnia. Am J Psychiatry 1976;133:1382–8.

16. Mormont MC, De Prins J, Levi F. [Study of circadian rhythms of activity by actometry: preliminary results in 30 patients with metastatic colorectal cancer]. Pathol Biol (Paris) 1996;44:165–71.

17. Sadeh A, Hauri PJ, Kripke DF, Lavie P. The role of actigraphy in the evaluation of sleep disorders. Sleep 1995;18:288–302.

18. Jean-Louis G, von Gizycki H, Zizi F, Spielman A, Hauri P, Taub H. The actigraph data analysis software. I. A novel approach to scoring and interpreting sleep-wake activity. Percept Mot Skills 1997;85:207–16.

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PITTSBURGH SLEEP QUALITY INDEX (PSQI)

  1. Top of page
  2. INSOMNIA SEVERITY INDEX
  3. MEDICAL OUTCOMES STUDY (MOS) SLEEP SCALE
  4. PITTSBURGH SLEEP DIARY
  5. PITTSBURGH SLEEP QUALITY INDEX (PSQI)
  6. References
  7. Supporting Information

General Description

Purpose.

The Pittsburgh Sleep Quality Index (PSQI) measures retrospective sleep quality and disturbances over a 1-month period for use in clinical practice and research (1). The PSQI discriminates between good and poor sleepers, and provides a brief, clinically useful assessment of multiple sleep disturbances.

Content.

Individual self-report items assess a broad range of domains associated with sleep quality, including: usual sleep wake patterns, duration of sleep, sleep latency, the frequency and severity of specific sleep-related problems, and the perceived impact of poor sleep on daytime functioning. Specific problems contributing to poor sleep that are assessed include: pain, urinary frequency, breathing difficulty, snoring, dreams, temperature, etc.

Developer/contact information.

Daniel J. Buysse, MD, Sleep and Chronobiology Center, Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, 3811 O'Hara Street, Pittsburgh, PA 15213. Fax: 1-412-624-2841.

Versions.

Japanese (validated) (2), German (3), and French (validated) (4).

Number of items in scale.

The instrument consists of 19 items. There are 5 additional questions rated by the bed partner/roommate that are not included in the total score, but may be useful for clinical purposes.

Subscales.

The 19-items are grouped into 7 equally-weighted component scores: 1) Subjective Sleep Quality (1 item); 2) Sleep Latency (2 items); 3) Sleep Duration (1 item); 4) Habitual Sleep Efficiency (3 items); 5) Sleep Disturbances (9 items); 6) Use of Sleeping Medication (1 item); and 7) Daytime Dysfunction (2 items).

Populations.
Developmental/target.

The PSQI was originally developed on 2 distinct groups of poor sleepers, patients with major depression and sleep disorder patients. A sample of good sleeper controls was also used in the original development (1). The sleep disorder sample consisted of patients referred to a sleep disorders center who presented with trouble initiating or maintaining sleep and/or disorders of excessive daytime somnolence.

Other uses.

The PSQI has been subsequently used and, in some cases, validated in a variety of clinical populations including: heterogeneous samples of chronic pain patients (5–7), fibromyalgia (8), temporomandibular joint disorder (9), post acute traumatic brain injury (validated) (10), bone marrow transplant (validated) (11), renal transplant (validated) (11), women with breast cancer (validated) (11), human immunodeficiency virus infection (12), irritable bowel syndrome (13), Parkinson's disease (14), older adults (15), primary insomnia (validated) (3), panic disorders (16), posttraumatic stress disorder (17), and sheltered battered women (18).

WHO ICF Components.

Body function, Impairment, Activity liimitation, Participation restriction, Environmental factor.

Administration

Method.

Self-report, paper and pencil.

Training.

Minimal.

Time to administer/complete.

Five to ten minutes.

Equipment needed.

None.

Cost, availability.

No cost; available from authors.

Scoring

Responses.
Scale.

Items 1–4 are free entry of: usual bed and wake times, minutes of total sleep time, and sleep latency (minutes). Items 5–18 are 4-point Likert scale responses pertaining to problem frequency: “not during the past month (0)”; “less than once a week (1)”; “once or twice a week (2)”; and “three or more times a week (3).” Item 19 is a 4-point Likert scale rating of overall sleep quality: “Very good (0)”; “Fairly Good (1)”; “Fairly Bad (2)”; “Very Bad (3).”

Score range.

The Global Score ranges from 0 to 21. All component scores range from 0 to 3.

Interpretation of scores.

Higher Global Scores indicate poorer sleep quality. An empirically derived cutoff score of > 5 distinguishes poor sleepers from good sleepers. A Global Score >5 indicates that a subject reports severe difficulties in at least 2 domains, or moderate difficulties in more than 3 areas.

Method of scoring.

The PSQI is hand-scored by assigning ordinal values to quantitative and qualitative items in order to generate seven equally-weighted component scores. The 7 component scores are summed to yield a single Global Score. Scoring instructions are provided in the original publication.

Time to score.

Five minutes.

Training to score.

Minimal.

Training to interpret.

Minimal.

Norms available.

Traditional norms are unavailable. Mean ± SD Global Score values for good sleeper controls (n = 52, 2.67 ± 1.70; Major depression (n = 34, 11.09 ± 4.31); Disorders of Initiating and Maintaining Sleep (n = 45, 10.38 ± 4.57); Disorders of Excessive Daytime Somnolence (n = 17, 6.53 ± 2.98) (1). Mean Global Score ± SD for healthy older adults, >80 years of age (n = 44, age = 4.75 ± 3) (15). Mean Global Score ± SD for heterogeneous outpatient chronic pain (n = 51, 11.57 ± 4.36) (5). Mean Global Score for Primary Insomnia (n = 80, 12.5 ± 3.8) (3).

Psychometric Information

Reliability.
Internal consistency.

In the original report (1), the 7 component scores had an overall Cronbach's alpha coefficient of 0.83, indicating high internal consistency. Component to Global Score correlation coefficients ranged from 0.35 (Sleep Disturbance) to 0.76 (Habitual Sleep Efficiency and Subjective Sleep Quality), with a mean component to global score Pearson's r correlation = 0.58. Individual items were also strongly intercorrelated with an internal reliability coefficient (Cronbach's alpha) = 0.83. Item to total correlation coefficients ranged from 0.20 (item #8; difficulty staying awake) to 0.66 (item #9, enthusiasm to get things done).

Test-retest.

The PSQI global score and component scores demonstrate adequate stability. Paired t-tests indicated no significant differences between global and component scores measured at T1 and T2 (mean of 28.2 days later). The Global Score Pearson product-moment correlation between T1 and T2 = 0.85 (P <0.001). Component score test-retest correlation coefficients ranged from 0.65 (Medication Usage) to 0.84 (Sleep Latency, P <0.001) (1).

Validity.
Criterion.

Criterion validity was originally established by evaluating the PSQI's ability to distinguish “good sleepers” from “poor sleepers” as defined by diagnoses based on the integration of expert structured clinical interviews, physical exam, and polysomnographic testing (1). The Global Score and all component scores differentiated poor sleeper groups from controls (P < 0.001). A post hoc Global Score cutoff > 5 correctly identified 88.5% of all patients and controls (kappa = 0.75, P < 0.001) with a sensitivity of 89.6% and a specificity of 86.5%.

Convergent validity with polysomnographic indices.

The individual PSQI estimate of sleep latency for the previous month was not found to be different from polysomnographically defined sleep latency (Pearson's r = 0.33, P < 0.001) (1). PSQI estimates of usual sleep duration and sleep efficiency were significantly greater than polysomnographic estimates, however (P < 0.001). The PSQI Global Score correlated weakly with PSG defined sleep latency (r = 0.20, P < 0.01). It should be noted that PSG data (2-night laboratory evaluation) and PSQI data (self-report of previous 1 month period) were based on different time frames. In a study of primary insomnia (n = 80), PSQI Global Score correlated significantly (P < 0.05) with PSG measures of Total Sleep Time (without stage 1) (r = −0.32), sleep efficiency (r = −0.32), and % of stage 2 sleep (−0.33) (3).

Convergent validity with daily sleep diaries.

In a sample of patients diagnosed with primary insomnia, PSQI estimates of sleep duration and sleep latency correlated strongly with daily sleep diary estimates (r = 0.81 and 0.71, P < 0.000, respectively) (3). Notably, the PSQI yielded reliably longer sleep latency times and shorter sleep duration times relative to diary estimates.

Convergent validity with other retrospective measures of sleep quality.

In medical patients (bone marrow transplant, renal transplant, breast cancer, and women with benign breast problems), PSQI Global Scores were found to be moderately to highly correlated with single and multiple item scales of sleep quality/problems (11). Specifically the PSQI global score correlated highly with sleep problems on the Symptom Experience Report (11), the Sleep Restedness item from the CES-D (19), and Sleep Quality from the Sleep Energy, and Appetite Scale (11) (correlation coefficients >0.69).

Divergent validity.

In medical populations, the PSQI global score was poorly correlated with measures unrelated to sleep quality such as nausea, vomiting, and taste changes (correlations <0.37) (11).

Sensitivity/responsiveness to change.

Although not designed as a treatment outcome measure, the PSQI has been shown to be sensitive to change in clinical trials of insomnia (20,21). Notably, Currie and colleagues found the PSQI to be sensitive to improvements in sleep quality after cognitive behavior treatment for insomnia secondary to chronic pain (22).

Comments and Critique

The PSQI is perhaps the most widely used general measure of sleep quality available. The strengths of this instrument are its range of coverage of multiple dimensions of sleep quality, its flexibility as a brief clinical tool, and its demonstrated utility in chronic pain research. Two primary limitations include the retrospective design, and omission of items pertaining to periodic limb movement/restless legs disorders (PLMS/RLS) in the global score. PLMS/RLS are important factors associated with sleep quality, especially in older adult populations with chronic pain. With regard to the retrospective nature of the instrument, the PSQI may be subject to forms of recall bias, such as recency effects and/or the tendency to differentially weight the most extreme nights of poor sleep in forming global impressions. Because PSQI items refer to ratings of sleep for the previous 1-month period, this measure may be less sensitive to estimating significant changes over time or with brief intervention periods. Combining the PSQI with prospective monitoring such as daily sleep diaries or actigraphy is recommended. It should also be noted that the cutoff score of 5 has been questioned and a score of 8 may be more sensitive and specific for certain populations (11).

Another weakness is that the daytime dysfunction component is comprised of only 2 items, enthusiasm and daytime sleepiness, and does not include an item related to fatigue. Fatigue is considered a hallmark symptom of insomnia, whereas daytime sleepiness is often a primary feature of other intrinsic sleep disorders. It should be noted, however, that the PSQI is one of the few measures of sleep that incorporate questions pertaining to daytime sleepiness. Supplementing an assessment of sleep in rheumatology patients with measures of fatigue (see review in this series) and one of the two most widely used measures of excessive daytime sleepiness (23,24) is strongly recommended. The Stanford Sleepiness Scale (SSI) (24) is a 7-item measure, designed to evaluate subjective changes in sleepiness using a 7-point scale. Items range from 1 = feeling active, vital, alert, or wide awake, to 7 = no longer fighting sleep, sleep onset soon; having dream-like thoughts. Strengths of the SSI are that it can be repeatedly administered within a 24-hour period and it is highly sensitive to change. The Epworth Sleepiness Scale (ESS) (23) is an 8-item index designed to measure the likelihood of falling asleep in certain situations, such as sitting and reading or in a car, while stopped at a traffic light, etc. Items are ranked on a 4-point scale, from 0 = would never doze, to 3 = high chance of dozing. The ESS is a reliable, well-validated measure of “usual” sleepiness and may be of particular value in the clinical assessment of sleep disorders such as sleep apnea in individuals with a variety of rheumatologic conditions .

Table  . Summary Table for Sleep Measures*
Measure/scaleContentItem formatsResponse formatMethod of administrationTime for administrationPrimary scale outputsValidated populationsPsychometric properties
ReliabilityValidityResponsiveness
  1. a

    ISI = Insomnia severity index; MOS = Medical Outcomes Study; PSD = Pittsburgh Sleep Diary; PSQI = Pittsburgh Sleep Quality Index; TMD = temporomandibular disorder.

ISISeverity of Sleep onset, maintenance and early morning awakening insomnia, sleep satisfaction, insomnia-related distress, daytime impairment7-items. Severity ratings of insomnia symptoms5-point Likert scaleSelf, clinician interview, and significant other report5 minutes or lessOverall severity index with established cut offsPrimary insomnia and medical/psychiatric insomnia, chronic painGoodGoodGood
MOSSleep initiation, quantity, maintenance, respiratory, problems, perceived adequacy of sleep, somnolence12 items: sleep continuity, and graded severity of common sleep disturbancesFree response and 6-point Likert scaleSelf, clinician interview5 minutes or lessOverall sleep problem severity indexPrimary care and multi-specialty care patients, Arthritis samples, back problemsGoodPoorInsufficient data
PSDTiming of meals, stimulants, medications, exercise, napping, bed and wake times, sleep continuity parameters, sleep quality, mood and alertness on waking17 items. Diary entries made twice a day (Morning and Night)Free response to standard questions, some categorical and 6-point Likert scale itemsSelf10 minutessleep latency, # of awakenings, wake after sleep onset time, total sleep time, sleep efficiencySleep disorders, Similar diaries used in chronic pain and fibromyalgiaGoodGoodGood
PSQISleep-wake patterns, sleep duration, sleep latency, frequency and severity of sleep disturbances, use of sleep medications, daytime consequences, overall/global sleep quality19-items. Questions pertaining sleep continuity parameters and graded severity and frequency of common sleep disturbances and behaviorsSome free entry and 4-point Likert scale itemsSelf5–10 minutesGlobal Sleep Quality Score with established cut-offs; 7 subscalesGeneral sleep disorders; Insomnia; breast cancer; transplant patients, chronic pain; fibromyalgia; TMDGoodGoodInsufficient data

References

  1. Top of page
  2. INSOMNIA SEVERITY INDEX
  3. MEDICAL OUTCOMES STUDY (MOS) SLEEP SCALE
  4. PITTSBURGH SLEEP DIARY
  5. PITTSBURGH SLEEP QUALITY INDEX (PSQI)
  6. References
  7. Supporting Information

Supporting Information

  1. Top of page
  2. INSOMNIA SEVERITY INDEX
  3. MEDICAL OUTCOMES STUDY (MOS) SLEEP SCALE
  4. PITTSBURGH SLEEP DIARY
  5. PITTSBURGH SLEEP QUALITY INDEX (PSQI)
  6. References
  7. Supporting Information
FilenameFormatSizeDescription
suppmat_184.pdf52KSupporting Information file suppmat_184.pdf

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