Arlet V. Nedeltcheva, MD; Jennifer M. Kilkus, MS; Jacqueline Imperial, RN; Dale A. Schoeller, PhD; Plamen D. Penev, MD, PhD
Acknowledgment: This study involved more than 250 inpatient days in the University of Chicago Sleep Research Laboratory, which is directed by Eve Van Cauter. The authors thank Theodore Karrison for advice on the selection of an appropriate approach for statistical analysis; Eve Van Cauter for advice during the planning of this study; and the staff of the University of Chicago Clinical Resource Center, Sleep Research Laboratory, Endocrinology Clinic, and Diabetes Research and Training Center for their skilled technical assistance.
Grant Support: By the National Institutes of Health (grants P01-AG11412, R01-HL089637, CTSA-RR 04999, and P60-DK020595).
Potential Conflicts of Interest: Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M10-0838.
Reproducible Research Statement:Study protocol, statistical code, and data set: Available from Dr. Penev (e-mail, firstname.lastname@example.org).
Requests for Single Reprints: Plamen D. Penev, MD, PhD, Section of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Chicago, 5841 South Maryland Avenue, MC-1027, Chicago, IL 60637; e-mail, email@example.com.
Current Author Addresses: Dr. Nedeltcheva: U.S. Food and Drug Administration, Center for Drug Evaluation and Research, 10903 New Hampshire Avenue, White Oak 22, Silver Spring, MD 20993.
Ms. Kilkus and Ms. Imperial: General Clinical Resource Center, University of Chicago, 5841 South Maryland Avenue, MC-7100, Chicago, IL 60637.
Dr. Schoeller: Nutritional Sciences, University of Wisconsin, 1415 Linden Drive, Madison, WI 53706.
Dr. Penev: Section of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Chicago, 5841 South Maryland Avenue, MC-1027, Chicago, IL 60637.
Author Contributions: Conception and design: D.A. Schoeller, P.D. Penev.
Analysis and interpretation of the data: A.V. Nedeltcheva, J.M. Kilkus, J. Imperial, D.A. Schoeller, P.D. Penev.
Drafting of the article: P.D. Penev.
Critical revision of the article for important intellectual content: A.V. Nedeltcheva, J.M. Kilkus, J. Imperial, D.A. Schoeller, P.D. Penev.
Final approval of the article: A.V. Nedeltcheva, J.M. Kilkus, J. Imperial, D.A. Schoeller, P.D. Penev.
Provision of study materials or patients: A.V. Nedeltcheva, J.M. Kilkus, J. Imperial.
Statistical expertise: A.V. Nedeltcheva, P.D. Penev.
Obtaining of funding: D.A. Schoeller, P.D. Penev.
Administrative, technical, or logistic support: A.V. Nedeltcheva, J.M. Kilkus, J. Imperial, D.A. Schoeller, P.D. Penev.
Collection and assembly of data: A.V. Nedeltcheva, J.M. Kilkus, J. Imperial, D.A. Schoeller, P.D. Penev.
Nedeltcheva A., Kilkus J., Imperial J., Schoeller D., Penev P.; Insufficient Sleep Undermines Dietary Efforts to Reduce Adiposity. Ann Intern Med. 2010;153:435-441. doi: 10.7326/0003-4819-153-7-201010050-00006
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Published: Ann Intern Med. 2010;153(7):435-441.
Sleep loss can modify energy intake and expenditure.
To determine whether sleep restriction attenuates the effect of a reduced-calorie diet on excess adiposity.
Randomized, 2-period, 2-condition crossover study.
University clinical research center and sleep laboratory.
10 overweight nonsmoking adults (3 women and 7 men) with a mean age of 41 years (SD, 5) and a mean body mass index of 27.4 kg/m2 (SD, 2.0).
14 days of moderate caloric restriction with 8.5 or 5.5 hours of nighttime sleep opportunity.
The primary measure was loss of fat and fat-free body mass. Secondary measures were changes in substrate utilization, energy expenditure, hunger, and 24-hour metabolic hormone concentrations.
Sleep curtailment decreased the proportion of weight lost as fat by 55% (1.4 vs. 0.6 kg with 8.5 vs. 5.5 hours of sleep opportunity, respectively; P = 0.043) and increased the loss of fat-free body mass by 60% (1.5 vs. 2.4 kg; P = 0.002). This was accompanied by markers of enhanced neuroendocrine adaptation to caloric restriction, increased hunger, and a shift in relative substrate utilization toward oxidation of less fat.
The nature of the study limited its duration and sample size.
The amount of human sleep contributes to the maintenance of fat-free body mass at times of decreased energy intake. Lack of sufficient sleep may compromise the efficacy of typical dietary interventions for weight loss and related metabolic risk reduction.
National Institutes of Health.
Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada
October 7, 2010
A Good Night's Sleep for Promoting Fat Loss
In the October issue of this journal, Nedeltcheva and coworkers (1) elegantly reported that getting too little sleep might prevent dieters from losing as much body fat as they otherwise would have. In this crossover study, 10 overweight adults were randomly assigned to sleep either 5.5 hours or 8.5 hours each night for 14 days in conjunction with moderate caloric restriction in a closed clinical research environment. The authors found that the participants lost the same amount of weight under both conditions; however, sleep restriction decreased the proportion of weight lost as fat by 55% and increased the loss of fat-free mass by 60%. These findings are novel and suggest that adequate sleep might be an important factor in successful weight loss.
Although the authors provided some mechanistic explanations to these findings, more studies are needed to confirm their observations. In particular, it is unknown whether the severity of sleep restriction influences the magnitude of fat loss. People having habitual sleep duration of 8.5 hours per night might be more "metabolically stressed" under 5.5 hour bedtimes than those having habitual sleep duration of 6.5 hours a day. Additionally, these findings have to be replicated in a real life setting, because the tightly controlled sleep laboratory setting does not provide information about other environmental factors that might influence compliance to weight-reducing diets. For instance, it is a very difficult task for short-duration sleepers not to overeat in our modern obesogenic environment when they are exposed to food for most of the day (2, 3). Moreover, people might adapt their total energy expenditure in a free-living environment because of the increased fatigue generally associated with lack of sleep. Interestingly, recent results have shown that short-term sleep restriction (2 nights of 4 hours in bed) was accompanied by a decrease in daytime spontaneous physical activity in healthy men studied in their natural environment (4). More importantly, the reduction in overall physical activity was explained by a shift toward less intense activities. Reductions in light physical activity (also called non-exercise activity thermogenesis, or NEAT) might be another compensatory mechanism by which lack of sleep influences energy expenditure. Future studies should measure NEAT when lack of sleep is experienced because of its important contribution to total energy expenditure (5).
Whether or not a good night's sleep is found to improve weight loss success in future studies, we should in the meantime rely on the large body of evidence showing that insufficient sleep is bad for our health and should not be part of a healthy active lifestyle.
1. edeltcheva AV, Kilkus JM, Imperial J, Schoeller DA, Penev PD. Insufficient sleep undermines dietary efforts to reduce adiposity. Ann Intern Med. 2010;153:435-41.
2. Chaput JP, Klingenberg L, Astrup A, Sj?din AM. Modern sedentary activities promote overconsumption of food in our current obesogenic environment. Obes Rev. (in press).
3. Chaput JP. Short sleep duration promoting overconsumption of food: a reward-driven eating behavior? Sleep. 2010;33:1135-6.
4. Schmid SM, Hallschmid M, Jauch-Chara K, Wilms B, Benedict C, Lehnert H, et al. Short-term sleep loss decreases physical activity under free-living conditions but does not increase food intake under time- deprived laboratory conditions in healthy men. Am J Clin Nutr. 2009;90:1476-82.
5. remblay MS, Esliger DW, Tremblay A, Colley R. Incidental movement, lifestyle-embedded activity and sleep: new frontiers in physical activity assessment. Appl Physiol Nutr Metab. 2007;32:S208-17.
University of Calgary, Calgary, AB, Canada
January 4, 2011
Insufficient sleep and obesity: blood oxygen saturation during sleep
The research paper from Nedeltcheva and colleagues (1) is impressive and I would like to congratulate authors for this new dimension into sleep and obesity research. Though the sample size is small (10 individuals) and study duration is short (14 days); there are compelling findings which is great.
It is not clear if the participants had normal sleep (though screening has been done) or disturbed (only sleep hours has been given i.e details of sleep record is not given). It would have been important if researchers had monitored oxygen saturation during the study period (blood oxygen saturation during sleep) and correlated. If the participants had broken sleep or had fluctuations in oxygen saturation during sleep, it could potentially confound the results and correlation between obesity and sleep only.
The research itself seems to have taken unusually long time to complete (from 2003 to 2008) for the given sample size and the modality of intervention. It might be the reason why this trial was not registry into 'clinical trial registry' (2) but the paper should have been reported according to CONSORT guidelines at least (3).
The research definitely gives physiological findings and good correlation but with the extent of study design, it is overstretching to say 'sleep well and stay slim' as mentioned in the accompanied editorial (4). Further study, bigger sample size and population based studies will be needed to generalize the findings.
1. Nedeltcheva AV, Kilkus JM, Imperial J, Schoeller DA, Penev PD. Insufficient Sleep Undermines Dietary Efforts to Reduce Adiposity . Ann Intern Med October 5, 2010 153:435-441;
2. WHO. International Clinical Trials Registry Platform (ICTRP). http://www.who.int/ictrp/en/ (accessed at 04 January 2011)
3. Schulz KF, Altman DG, Moher D. CONSORT 2010 Statement: Updated Guidelines for Reporting Parallel Group Randomized Trials. Ann Intern Med. 2010;24.
4. Taheri S, Mignot E. Sleep well and stay slim: dream or reality? . Ann Intern Med. 2010 Oct 5;153(7):475-6.
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