OBJECTIVE: Obesity and chronic sleep deprivation have both become increasingly pervasive medical problems in recent years. The prevalence of adult obesity has doubled over the past 30 years and continues to increase. In addition, industrial societies attach an economic value to maximizing the waking period to the longest tolerable limit by sleeping as little as possible. Average sleep time has decreased over the last century by 2 hours. Chronically sleeping less has been associated with increased weight, endocrine and metabolic health risks including glucose intolerance, cardiovascular disease, and mortality. The possibility that the current epidemic of obesity and metabolic health risks may be partially related to insufficient sleep is now being recognized. The objective of this proof-of-concept controlled trial is to investigate the impact of increasing sleep time in chronically sleep-deprived, obese subjects.
STUDY POPULATION: 18-50 year old, obese (BMI 29-55) men and premenopausal women, chronically sleep deprived, recruited from the Baltimore-Washington metropolitan area. Chronic sleep deprivation will be verified by the use of sleep logs and the use of actigraphy before entry into the study. Secondary causes of sleep deprivation such as insomnia, psychological (depression), and medical conditions associated with poor sleep quality (including obstructive sleep apnea) will be exclusionary criteria.
DESIGN: This is a randomized, 12-month duration, comparison-controlled clinical trial of an extension of sleep up to approximately 7 hours and 30 minutes (Intervention Group) or continuation of habitual short sleep schedule (Comparison Group). The proposed treatment is an educational and behavioral intervention aimed at increasing sleep in a non-pharmacological fashion. The main analysis of the study will be to determine if additional sleep will result in a significant difference in body weight at the end of 12 months between the Intervention Group and the Comparison Group. In addition, we would like to establish whether 12 months of additional sleep will result in: a) a decreased prevalence of metabolic syndrome; and b) changes in the endocrine profile (i.e. inducing changes in leptin \[increase\] and ghrelin \[decrease\] opposite to the changes associated with chronic sleep deprivation). At the end of the 12-month intervention study (Phase 1, Efficacy \[Randomized Phase\] Study), all participants will be given information about the potential benefit of more sleep and encouraged to increase sleep time. Health teaching about proper nutrition and adequate exercise will also be provided at that time to the Intervention and Comparison Groups. All participants will be evaluated 6 months later to assess the effects of this intervention in a real-life situation, and offered participation in a three-year extension with semi-annual visits (Phase 2, Effectiveness \[3 Year Follow-Up Phase\] Study), for which matched external comparison subjects will also be recruited ad hoc.
OUTCOME PARAMETERS: body weight, average number of hours of sleep/night, fasting glucose and insulin, oral glucose tolerance test, leptin, ghrelin, adiponectin, other relevant endocrine and anthropometric measures, body composition, various metabolic parameters, food intake, energy expenditure, and quality of life measures.
The study was terminated early for reasons of apparent futility of continuing accrual of participants according to the original study plan. The decision was based on independent analysis of data acquired during the initial feasibility phase and from interim analysis of early results that failed to document objectively the achievement of substantive and meaningful differences between experimental and control groups with respect to amounts of sleep extension, changes in metabolic parameters, or changes in weight. Feasibilities of achieving objective and substantive differences in these parameters were integral to the methodology of the original study plan and required to meet the statistical power calculations for the controlled trial.
