Fitness professionals have another reason to emphasize the importance of sleep to clients. Short sleep of less than 5 hours per night is significantly associated with weight gain in both men and women, according to a large study of more than 21,000 apparently healthy adults. Researchers from St. Luke’s International Hospital, in Tokyo, analyzed data from the annual health check-ups of 21,469 individuals between 2005 and 2008 and evaluated the relationship between average nightly sleep duration, body mass index greater than or equal to 25, and weight gain. People who slept less than 5 hours per night were more likely to gain weight and to become obese compared with those who slept 7 hours. Those who slept more than 8 hours did not differ significantly from those who slept 7 hours.
“Sleeping is a fundamental function for all living organisms. Sufficient sleep duration makes both exercise and weight control more effective. Our research suggests that getting adequate sleep not only feels good, but is also good for your health,” said lead study author Daiki Kobayashi, MD, based at St. Luke’s International Hospital.
The study was published in Sleep Breath (2011; doi: 10.1007/s11325-011-0583-0).