In recent years, sleep disturbances and the health-related quality of life (QOL) experienced by adults with cancer, during and after cancer treatment, have received increasing attention in the scientific literature. The purpose of this paper was to systematically review current methodological approaches to the study of sleep disturbances and QOL in adults with cancer. Databases were searched to identify longitudinal studies of adults with cancer that measured sleep disturbances and QOL in the past 10 years. The review was focused in five primary areas: trends in publication, measurement of sleep and QOL, study design, changes in sleep disturbances and QOL, and the level of this evidence. Of the 40 studies that met the authors' criteria for inclusion, 75% were descriptive in design and 25% were intervention studies. Studies on sleep and QOL among cancer patients have become more common since 2000, include a range of sample sizes and settings, use a variety of measures of sleep and QOL, and examine patients undergoing many types of cancer therapies. No programs of research have been developed in sleep disturbances and QOL in adults with cancer. The ‘evidence’ that can be drawn from such studies is obviously weak. Current approaches usually describe changes over time, but have not described whether a relationship exists between sleep disturbances and QOL in adults with cancer. Directions for future research are suggested. Copyright © 2006 John Wiley & Sons, Ltd.