Chronic Sleep Deprivation as a Risk Factor for Metabolic Syndrome and Obesity

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 30-50) 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.

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.

Eligibility Criteria:
* INCLUSION CRITERIA:

  18 to 50 year old obese men and premenopausal women

BMI between 29-55

Chronically (for more than 6 months) sleep-deprived, defined as sleeping on a regular basis less than or equal to approximately 6-1/2 hours/night by history and objective devices (wrist activity monitors and sleep logs).

INCLUSION CRITERIA: External comparison subjects for extension of Effectiveness Study must meet the criteria above.

EXCLUSION CRITERIA:

Diagnosed sleep disorders including:

* Chronic insomnia
* Untreated sleep disordered breathing (sleep apnea at a level of severity \[using standardized criteria for measurement\], or diagnosed UARS \[upper airway resistance syndrome\] that would impair the ability to increase sleep duration \[Intervention Group\] or maintain sleep duration \[Comparison Group\]. CPAP treatment that has been in place for 3 months or more and improves sleep is acceptable).
* Restless leg syndrome or periodic limb movement disorder
* Parasomnias (including REM sleep behavior disorders, confusional arousals, sleep terrors, sleepwalking, sleep violence)
* Primary bruxism is allowed as long as it does not interfere with the ability to sleep an additional 90 minutes a night
* Narcolepsy
* Central apnea.

Unstable weight (voluntary losses in BMI greater than 5% over the past 6 months); currently being enrolled in a weight loss program

Untreated or uncontrolled diabetes

Severe uncontrolled hypertension

Other chronic organ disease diagnosis including:

* COPD
* Chronic cardiac arrhythmia requiring treatments
* Gastro-esophageal disorders associated with sleep-related symptoms.

Medications

* chronic use of prescription or over-the-counter medications known to affect sleep (e.g., systemic steroids, NSAIDs)
* current anticonvulsant therapy

Chronic fatigue syndrome and fibromyalgia

Acromegaly, hypothyroidism (unless on a stable replacement dose of thyroid hormone), Cushing disease or other endocrine disorders known to affect sleep

Poorly controlled major depression (subjects who have been on a stable pharmacological antidepressant treatment for 3 months and are in remission without substantial weight gain are eligible).

Other current DSM-IV diagnoses, including:

* Eating disorders such as bulimia nervosa and binge eating disorder
* Anxiety disorders such as PTSD and panic attacks
* Mania
* Schizophrenia.

Medication and substance abuse such as excessive alcohol consumption or drug abuse or dependence that may pose a threat to compliance

Being a rotating worker, shift worker (working evenings or nights), or long distance commuter (more than approximately 90 minutes each way), traveling frequently outside of time zone; being in an occupation that may require special vigilance such as driving a truck, bus, or cab; operating heavy machinery; being a pilot or air traffic controller

Being likely to move to a different geographical area during the study

Having a sleep partner that would make compliance with study requirements difficult

Pregnancy and lactation

Menopause

Chronic excessive caffeine use (habitual intake of more than 500 mg/day)

Any condition that in the opinion of the principal investigator makes study participation and compliance problematic.