Researchers found that:
- Less than 6.5 hours of sleep or more than 8.5 hours of sleep was linked to higher body fat
- High quality sleep was associated with lower body fat, while poor sleep correlated with higher body fat
- Consistent wake times and going to sleep at the same time every day (particularly the consistent wake time) were most strongly linked with lower body fat
The difference in body weight was greater with more variation in sleep pattern. Women whose sleep patterns varied by 90 minutes a night had higher body fat than those whose sleep varied by 60 minutes or less on average. Body fat also varied with sleep quantity; women who slept between 8 and 8.5 hours a night had the lowest body fat. The greatest effect was seen in women who woke up at the same time every morning seven days a week.
Although this was a small, short duration study with study participants selected from a limited pool (only young, only college educated, etc.) and was not blinded or controlled, other studies have shown that sleep has an effect on physical activity, appetite, and the hormones that control appetite and metabolism. According to those studies skimping on sleep boosts production of ghrelin, (a hormone that controls food cravings) and decreases production of leptin, (a hormone that helps prevent over-eating). A body of research conducted over the last few years that ties quality and quantity of sleep to weight loss and better weight control included a randomized trial published in the journal Obesity which found that among overweight and obese women ages 35 to 55 engaged in a weight loss programs, getting an adequate amount of good quality sleep increased the chance of weight loss success by 33 percent.
While researchers don’t know exactly how sleep schedules affect body mass and fat, consistent sleep patterns are part of good sleep hygiene. Click here to learn more about improving your sleep and the importance of sleep hygiene.
The report was published online in the November issue of the American Journal of Health Promotion.
Forbes;Change Your Sleep Schedule To Lose Weight, Study Shows; Melanie Haiken,11/21/2013
Steady Sleep Schedule May Help Keep Weight Off; Philly.com; Steven Reinberg, 11/21/2013