Not all of the studies found such drastic differences in hormone levels. But many have also documented study subjects eating more and/or more often in the lab after they have had consecutive nights of partial sleep deprivation. One study tested women, reducing their nightly sleep from seven to four hours over the course of four nights. During the sleep deprivation phase, women ate an average of about 400 more calories daily than they had at the beginning of the session—and even gained weight over the course of the short study.
As Shlisky and her colleagues point out in their paper, people who are awake longer simply have more opportunities to eat. "Partial sleep deprivation may increase the risk of overeating in the evening due to low circulating leptin levels and additional time spent awake," the researchers noted, adding that "evening and late-night hours are when overeating of less-healthful foods is most likely to occur." Furthermore, additional research that shows "impulse control and delayed gratification are lowered with sleep deprivation, perhaps making sleep-deprived individuals more vulnerable to hedonic eating," rather than resort to healthful foods to sate hunger.
Stressed and sleepy
Do these extra waking hours also help us get in more physical activity? As with eating, it might seem reasonable to think that being awake longer would lead to more beneficial activity, resulting in more energy expended. Not necessarily, according to the researchers. One study found that after just two nights of being allowed only four hours asleep, subjects had "significantly lower activity" than those subjects allowed eight hours rest. Although lab study results on exercise levels after sleep deprivation have been mixed, people generally report feeling more lethargic and less capable of getting the recommended moderate- to high-intensity exercise. So, although one might spend an extra two to four hours prone in bed, during the 16 to 17 hours of wakefulness a well-rested person would be more likely to meet exercise recommendations and improve his or her metabolism.
Sleep deprivation can also lead to muscle loss and fat gain. With too little sleep, the body is also more likely to produce the stress-response hormone cortisol. After sleep deprivation, subjects in several studies had higher levels of cortisol later in the day, a time when it should be tapering off to prepare the body for rest. Heightened cortisol prompts the body to store more fat and be more inclined to use other soft tissue, such as muscle, as energy, which means that sleep-deprived dieters lose more muscle and gain more fat than do those who are well rested. One study found that after two weeks of minor calorie restriction (10 percent less than their daily energy expenditure), subjects who were getting 5.5 hours in bed a night lost just 0.6 kilogram of fat but 2.4 kilograms of other tissue, such as muscle; subjects who got 8.5 hours slumber each night lost 1.4 kilograms of fat and 1.5 kilograms of other tissue. "Some of these metabolic effects occur pretty quickly," Mehra notes.
Parsing zzz's
The studies reviewed in the current report were all small and of short duration. But larger, long-term epidemiologic studies have come back with similar results. Nevertheless, the relationship between sleep deprivation and weight gain is still not crystal clear. Obesity itself can contribute to sleep loss. Frequent co-occurring conditions, such as sleep apnea (disrupted breathing during sleep), are large contributors to disrupted and poor-quality sleep in the general population. So is obesity causing sleep deprivation, rather than the other way around? "There could be a bidirectional relationship," Mehra says. Although sleep apnea and other conditions can make for low-quality sleep, which can then also lead to heart disease, Mehra suggests that there is ample data that show people who began as normal weight and healthy but did not get enough sleep, over time developed worse health outcomes.
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Add CommentThis is interesting. As an older, retired person whose diurnal cycle has gone through changes, I have noticed how much harder it is to keep the weight off despite regular exercise. The changes in sleep may be part of it.
Reply | Report Abuse | Link to thisI am intrigued by the author's reference at the beginning of the article to "solid sleep." According to David Randall's book "Dreamland," there's evidence that the "natural" (that is, before the invention of the electric light bulb) sleep cycle is segmented into a "first sleep" and a "second sleep," with an hour or two between segments. Now that I can sleep without the need to get up by a particular time, I definitely find myself sleeping that way, with a total average of about seven hours.
All this evidence and yet we wonder why there is an epidemic of obesity? Hasn't anyone ever thought to correlate the trend to push more and more people into shift work with its negative effects on sleep with obesity over time and large scale geographic areas? Why don't we outlaw shiftwork? It leads to car accidents, heart attacks and weight gain. Where are the insurance companies? They stand to gain if these problems are solved and they have the financial muscle to force other industries to reduce or eliminate shift work and improve health and accident rates.
Reply | Report Abuse | Link to thisConnection between sleep and obesity is intriguing. Sound sleep reflects wellness. Wellness reflects smartness. Smartness reflects non-obesity. Thus, there is a very strong relationship between sleep and obesity.
Reply | Report Abuse | Link to thisS. N. Tiwary
Director, Former V. C. (Acting)
Getting more sleep might seem a "simple" solution to the issues of weight gain and mental absence; but for many people these days, working two (or MORE) jobs in order to keep their families' heads above water, sleep has become optional.
Reply | Report Abuse | Link to thisNot only the wealth, but the HEALTH, of the populace always suffers when feudalism reigns.
Well, I sleep eight hours per night and I feel well. To bed at ten and up at 6. Occasionally but seldom watch a movie till eleven or come home late on Saturday night, but sleep out on Sunday morning. Why not arrange your life aroun sleep?
Reply | Report Abuse | Link to thisDear "Pazuzu". "As an older, retired person", your problem with the regulation of body weight is related to the DECREASED Resting metabolic rate.... Read more here GOOD APPETITE from Switzerland.... http://www.vitasanas.ch/wp/wp-content/uploads/2012/09/BOOK5_Resting_Metabolic_Rate_RMR.pdf
Reply | Report Abuse | Link to thisFINALLY a weight gain is correlated with an ENERGY (Calories) intake greater than the PERSONAL DAILY CALORIC REQUIREMENT (PDCR) ! It is obvious, that less sleep means MORE time to eat... Read more abaout PDCR with the link below! http://www.vitasanas.ch/fileadmin/user_upload/pdf/BOOK4_The_personal_caloric_requirement__2_.pdf
Reply | Report Abuse | Link to this" One study also found a change in another eating signal called peptide YY"!! We published 1996 a paper in "Nature" about the KEY role of the NPY (of the PEPTIDE YY family"). http://www.nature.com/nature/journal/v382/n6587/abs/382168a0.html
Reply | Report Abuse | Link to thisIn 2002, the PHARMA-Company in which the discovery was made (NOVARTIS, BASEL) STOPPED all activities on obesity research just because the "body is smarter"!!!! See more in the book "eating healthy and dying obese" http://www.vitasanas.ch/wp/?page_id=370
See also chapter in the book about "Science feeds the confusion"!! http://www.vitasanas.ch/fileadmin/user_upload/pdf/BOOK-chapter_1_confusion.pdf
MUCH better to ARRANGE your LIFE around your LIFE NOT youe sleep! ENJOY LIFE! Science cretes many time ONLY confusion... I am a scientist!!!!
Reply | Report Abuse | Link to thisEvery man is unique so this kind of statistical survey how much useful?How much sleep require is depend on every man on his gene, his upbringing,there are many factors are responsible for man`s obesity , so draw a conclusion only for sleep is futile
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