Sleep Restriction Promotes Weight Gain in Humans
Regular readers already know that lack of sleep is increasingly seen as one of the major drivers of calorie overconsumption and weight gain. Those, who remain sceptical may be interested in a paper by Andrea Spaeth and colleagues from the University of Pennsylvania, just published in SLEEP. This, to date the largest randomised controlled trial of experimental sleep deprivation on eating behaviour shows that individuals who are sleep deprived will consume up to 500 extra calories per day compared to individuals who get adequate sleep. The researchers studied 225 health adults randomised 8:1 to an experimental condition (including five consecutive nights of 4 h time in bed [TIB]/night, 04:00-08:00) or to a control condition (all nights 10 h TIB/night, 22:00-08:00). Not only did sleep-restricted subjects gain more weight (0.97 kg) than control subjects (0.11 kg) but sleep-restricted weight gain was greater in African Americans than Caucasians and in males than in females. Sleep-restricted subjects consumed 30% extra calories (over 550 additional calories mainly between 22.00 and 04.00), easily accounting for the observed weight gain. Thus, the authors conclude that chronically sleep-restricted adults with late bedtimes may be more susceptible to weight gain due to greater daily caloric intake and the consumption of calories during late-night hours. Given what we know about how sleep deprivation affects appetite and metabolism, these findings should come as no surprise. Let us not forget that a key characteristic of “Westernised” society is significant sleep deprivation and about 40% of adult Canadians report at least one symptom of insomnia with over 10% of Canadians reaching for sleeping aids. Reason enough to consider sleep (or rather lack thereof) a key driver of the obesity epidemic. @DrSharma Edmonton, AB Spaeth AM, Dinges DF, & Goel N (2013). Effects of Experimental Sleep Restriction on Weight Gain, Caloric Intake, and Meal Timing in Healthy Adults. Sleep, 36 (7), 981-990 PMID: 23814334 .
Even a Modest Lack of Sleep Can Adversely Affect Metabolism
Kevin is a healthy 24 year old student with a BMI of 25, who usually sleeps almost 8 hrs (7:45 to be precise). He is usually fast asleep within 20 mins of lying down and has good quality sleep. Having always had some interest in research, Kevin (together with 18 other healthy young male students) volunteers to take part in a study on sleep restriction at the University of Surrey, UK, conducted by Denise Robertson and colleagues, the results of which are now published in METABOLISM. Before beginning the study, the researchers measured Kevin’s body composition (he had 16% body fat), his blood pressure (normal), glucose and insulin levels (normal), adiponectin, leptin and even performed a euglycemic insulin clamp to measure his insulin sensitivity. As a result of randomization, Kevin ended up in the sleep restriction group and now had to set his daily alarm clock for 1.5 hours before his normal waking time for the next three weeks. He was also told not to nap during the day. Close activity monitoring ensured that he did not cheat on the protocol. During the first two weeks of sleeping less, Kevin’s body weight actually decreased by about 4 lbs, only to increase slightly above baseline at the end of the study. Similarly, he became more insulin resistant after one week of sleep deprivation, but this returned to normal at the end of three weeks . Although not much happened to Kevin’s leptin levels during the first two weeks, they fell sharply in week three and were significantly lower than at baseline by the end of the study. (Not much happened with Kevin’s adiponectin levels.) While Kevin and his colleagues in the sleep deprivation group were experiencing these hormonal changes, not much was happening to the students randomizes to the habitual sleep control group. As the authors note, the metabolic response to mild sleep deprivation appears to be variable over time with some early changes that may not be sustained over time. However, they also note that effects of lowered levels of leptin (seen in the third weed) on hypothalamic centres regulating appetite, could potentially lead to increased food intake and weight gain. This, would need to be looked at in studies with longer duration. Also, what happened to young healthy Kevin, may not be typical for older subjects, women, or those with excess weight or diabetes. Nevertheless, the study does show that even… Read More »
Will Turning Off Your Bedroom Lights Make You Lighter?
Regular readers are well aware of the mounting evidence on the importance of sleep deprivation as a driver of obesity. Now, a paper by Kenji Obayashi from the Nara Medical University (Japan), published in the Journal of Clinical Endocrinology and Metabolism, takes this issue one step further. The researchers looked at the relationship between intensity of light in the bedroom, BMI and other variables in 528 elderly individuals. Compared with the individuals with no to very low night-time light exposure (<3 lux – note: a full moon night is about 1 lux, twilight is about 3 lux), those with higher exposure (average ≥3) were significantly heavier (by about 4 lbs), had about one unit higher BMI, and about two cms larger waistlines. Individuals with greater light exposure, were almost twice as likely to meet BMI criteria for obesity. These associations were independent of numerous potential confounders, including demographic and socioeconomic parameters. Obviously, the meaning of these data are far from conclusive and it would be premature to draw any inferences regarding causality. It may however be plausible to hypothesize that even minimal amounts of night-time light exposure can affect quality of sleep, thereby in turn, affecting metabolism (in ways in which we now know sleep-deprivation to do). It would certainly be of interest to see how such findings can be reproduced in a more experimental setting – I would not be surprised if these findings can be confirmed and further highlight the importance of ensuring not only adequate duration but also quality of sleep. AMS Edmonton, AB Obayashi K, Saeki K, Iwamoto J, Okamoto N, Tomioka K, Nezu S, Ikada Y, & Kurumatani N (2013). Exposure to Light at Night, Nocturnal Urinary Melatonin Excretion, and Obesity/Dyslipidemia in the Elderly: A Cross-Sectional Analysis of the HEIJO-KYO Study. The Journal of clinical endocrinology and metabolism, 98 (1), 337-44 PMID: 23118419 .
Does More Sleep Increase Physical Activity in Kids?
Sleep (or rather the lack of it) is increasingly implicated as a major societal and biological “root cause” of obesity. Regular readers will be familiar with previous posts on how sleep deprivation affects appetite and energy metabolism. Now, a study by Canadian Obesity Network bootcamper Michelle Stone and colleagues from the University of Toronto, publish a paper in Preventive Medicine suggesting that kids who reach recommended sleep levels throughout the week are more physically active than kids who don’t. This study looks at the relationship between physical activity (accelerometry) and reported sleep (parents) in about 850 kids. The main finding of the paper is that on weekdays, children who slept the least (<9 hours) were more overweight/obese and less active in terms of overall intensity than those attaining ≥10 hours. Furthermore, weekday-weekend sleep regularity mattered in that overall intensity was higher amongst kids maintaining recommended sleep (>9 hours) compared to those engaging in weekend-catch-up-sleep. Thus, the authors suggest that appropriate weekday-weekend sleep (regularity) may supports healthy activity and should be an important health-promoting strategy. Although studies like this do not prove causality, they certainly fit nicely with the rapidly growing body of evidence suggesting that lack of sleep may well be an important “root cause” of the obesity epidemic. Perhaps time to bring back those afternoon naps? AMS Edmonton, Alberta Stone MR, Stevens D, & Faulkner GE (2012). Maintaining recommended sleep throughout the week is associated with increased physical activity in children. Preventive medicine PMID: 23201000 .
Sleep Yourself To a Leaner You?
Regular readers will appreciate the rapidly accumulating body of evidence linking much of the current obesity epidemic to a rather marked reduction in sleep that has befallen us all (not least our kids). In a commentary published in the Canadian Medical Association Journal (CMAJ), Jean-Philippe Chaput and Angelo Tremblay discuss this increasing evidence pointing to a critical role of sleep (or lack thereof) in weight management. As the authors note: “Chronic sleep restriction is pervasive in modern societies, and there is robust evidence supporting the role of reduced sleep as contributing to the current obesity epidemic. New studies provide evidence that insufficient sleep enhances hedonic stimulus processing in the brain underlying the drive to consume food; thus, insufficient sleep results in increased food intake. In addition, lack of sleep has been reported to decrease plasma leptin levels, increase plasma ghrelin and cortisol levels, alter glucose homeostasis and activate the orexin system, all of which affect the control of appetite and might compromise the efficacy of dietary interventions.” Although interventions focusing on sleep are still scarce, they do discuss one randomised controlled trial in which decreased sleep (5.5 vs. 8.5 hours) together with a calorie-deficient diet resulted in amost 60% less weight loss than in the long sleepers. In another study, participants in a 6-week weight loss intervention who reported better sleep and/or sleeping at least 7 hours experienced almost 35% more weight loss than those who did not. As the authors point out: “The Canadian Obesity Network recently launched a set of practitioner tools — the 5As of Obesity Management (ask, assess, advise, agree and assist) — that highlight the importance of addressing sleep for weight management.” They recommend the use of the Pittsburg Sleep Quality Index for screening and diagnosing common sleep/wake disorders and remind clinicians that the association between inadequate sleep and obesity can also be confounded by factors such as stress, depression, psychosocial problems, chronic illness and the use of hypnotic agents. Reason enough to go well beyond ‘eat-less-move-more’ (ELMM) recommendations on obesity management. AMS Edmonton, Alberta photo credit: Michael Sissons via photo pin cc
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