Late Bedtimes and Less Sleep May Lead to Weight Gain in Healthy Adults

June 28, 2013 — A new study suggests that healthy adults with late bedtimes and chronic sleep restriction may be more susceptible to weight gain due to the increased consumption of calories during late-night hours.

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In the largest, most diverse healthy sample studied to date under controlled laboratory conditions, results show that sleep-restricted subjects who spent only four hours in bed from 4 a.m. to 8 a.m. for five consecutive nights gained more weight than control subjects who were in bed for 10 hours each night from 10 p.m. to 8 a.m. The study found an overall increase in caloric intake during sleep restriction, which was due to an increase in the number of meals consumed during the late-night period of additional wakefulness. Furthermore, the proportion of calories consumed from fat was higher during late-night hours than at other times of day.

"Although previous epidemiological studies have suggested an association between short sleep duration and weight gain/obesity, we were surprised to observe significant weight gain during an in-laboratory study," said lead author Andrea Spaeth, a doctoral candidate in the psychology department at the University of Pennsylvania in Philadelphia, Pa.

The study, which appears in the July issue of the journal SLEEP, was conducted in the Sleep and Chronobiology Laboratory at the Hospital of the University of Pennsylvania. The study group comprised 225 healthy, non-obese individuals, ranging in age from 22-50 years. Subjects were randomized to either the sleep restriction or control condition and spent up to 18 consecutive days in the laboratory.

Meals were served at scheduled times, and food was always available in the laboratory kitchen for participants who wanted to eat at other times of day. Subjects could move around but were not allowed to exercise. They were permitted to watch TV, read, play video games or perform other sedentary activities.

The study also found that during sleep restriction males gained more weight than females, and African Americans gained more weight than Caucasians.

"Among sleep-restricted subjects, there were also significant gender and race differences in weight gain," said Spaeth. "African Americans, who are at greater risk for obesity and more likely to be habitual short sleepers, may be more susceptible to weight gain in response to sleep restriction. Future studies should focus on identifying the behavioral and physiological mechanisms underlying this increased vulnerability."

The American Academy of Sleep Medicine reports that weight gain is a risk factor for obstructive sleep apnea (OSA), a common sleep illness that has a severe impact on health and quality of life. The risk of OSA increases as the degree of additional weight increases, with an extremely high prevalence of OSA in people with morbid obesity. Anyone who has experienced recent weight gain and has symptoms of OSA, such as loud and frequent snoring, should be evaluated by a board certified sleep medicine physician.

Mood-Boosting Movement

A heart-pumping workout can be as effective as prescription drugs when it comes to improving overall mood and reducing the symptoms of depression.


A growing body of research establishes that the feel-good buzz that lingers when you leave the gym isn’t all in your head. In fact, a heart-pumping workout can be as effective as prescription drugs when it comes to improving overall mood and reducing the symptoms of depression — without the side effects.

“Being physically active is one of the most powerful ways of dealing with depression, whether mild, moderate or even severe,” says Kate F. Hays, PhD, clinical psychologist and past president of the American Psychological Association’s Division of Exercise and Sport Psychology.

While much of the research has focused on the benefits of aerobic exercises like walking, jogging, biking orswimming, Hays notes that rhythmic, repetitive and even slightly aggressive exercises that involve diaphragmatic breathing can also help alleviate depression.

The medicine-ball slam, for example, involves lifting a specially designed, weighted ball overhead and then banging it to the ground. (For step-by-step, how-to instructions, check out our Show Me How video.)

“There’s an old theory that depression is anger turned inward. One of the wonderful things about using an exercise like this one is that you can slam those feelings away,” says Hays. “It involves your entire body, it’s core strengthening, you can track your improvement and it’s also very easy to do. That’s important, because someone who is depressed isn’t going to start something that takes a lot of effort to learn.”

As little as 10 minutes of exercise can improve mood and energy levels, according to research by the Association for Applied Sport Psychology (AASP). To really wrestle the blues into submission,  though, the AASP recommends moderate activity for 30 minutes three times a week. It’s also important to choose a routine that works with your lifestyle, that you enjoy, and that you will continue — even on the days when you’re down in the dumps.