NEW YORK (Reuters Health) - Failure to get a full night’s sleep can lead to weight gain or compromise the beneficial effects of a reduced calorie diet on total body adiposity, according to presentations at SLEEP 2009, the annual meeting of the Associated Professional Sleep Societies, underway this week in Seattle.
“Reduced sleep duration has become a common aspect of the westernized lifestyle defined by physical inactivity and overeating,” Dr. Plamen Penev, from the University of Chicago, told Reuters health. “Diet-induced weight loss is a major behavioral strategy for metabolic risk reduction. However, its efficacy in the setting of reduced sleep duration is unknown.”
Dr. Penev and his associates studied nine healthy overweight volunteers (mean age 40 years, mean BMI 27.5). The subjects completed two 14-day studies at least 3 months apart; during which they spent either 5.5 hours or 8.5 hours in bed per night.
During both study periods, they consumed a nutritionally balanced caloric intake equal to 90% of their resting metabolic rate, and weight loss during each treatment was similar (mean 3.0 vs 2.9 kg, respectively).
However, fat represented only 26% of the weight loss during sleep restriction as compared with 57% during the 8.5-hour bedtime condition (p = 0.031), indicating increased loss of lean body mass during reduced sleep conditions.
Dr. Penev and colleagues conclude that the neuroendocrine response to the reduced calorie diet was amplified by recurrent sleep restriction, as evidenced by increased concentrations of the orexigenic hormone ghrelin.
In another study by Dr. Siobhan Banks and associates at the University of Pennsylvania in Philadelphia, 92 healthy adults (22 to 45 years old) spent 2 nights of unrestricted sleep (10 hours time in bed), followed by 5 nights of 4 hours time in bed, then four nights of recovery. Nine control subjects spent 10 hours/night in bed during the 11-day protocol.
Sleep restricted subjects experienced a mean weight gain of 1.31 kg during the protocol (p < 0.0001), even though they reported decreases in appetite, food cravings, and food consumption. By contrast, there was no significant weight gain in the control group.
In a prepared statement, Dr. Banks, who is currently working at the University of South Australia, noted that “During real-world periods of sleep restriction…keeping up regular exercise is just as important as what food you eat, so even though people may feel tired, exercising will help regulate energy intake balance.”
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