Lack of sleep, shift work ups obesity risk

BOSTON, April 12 (UPI) -- People who don't get enough sleep or who sleep outside the "internal biological clock" are at increased risk of diabetes and obesity, U.S. researchers said.

Lead study author Orfeu M. Buxton, a neuroscientist at Brigham and Women's Hospital in Boston, said unlike epidemiological studies, this study examined humans in a controlled lab environment over a prolonged period, and altering the timing of sleep, mimicking shift work or recurrent jet lag.

Buxton and colleagues hosted 21 healthy participants in a completely controlled environment for nearly six weeks.

Participants started with getting optimal sleep -- approximately 10 hours per night -- followed by three weeks of 5.6 hours of sleep per 24-hour period and with sleep occurring at all times of day and night simulating the schedule of rotating shift workers. The study closed with the participants having nine nights of recovery sleep at the usual time.

The study published online in Science Translational Medicine found prolonged sleep restriction with simultaneous circadian disruption decreased the participants' resting metabolic rate and glucose concentrations in the blood increased after meals due to poor insulin secretion by the pancreas.

A decreased resting metabolic rate could translate into a yearly weight gain of more than 10 pounds, while increased glucose concentration and poor insulin secretion could lead to an increased risk for diabetes, Buxton said.