HealthDay News — Prolonged inadequate sleep at irregular times lowers the resting metabolic rate and leads to defects in pancreatic insulin secretion, which may increase the risk for obesity and diabetes, study data indicate.

Impaired glucose regulation and metabolism was associated with shortened sleep time and variations in bed time in a 39-day study designed to mimic shift work for night workers, Orfeu M. Buxton, PhD, and colleagues from Brigham and Women’s Hospital in Boston reported in Science Translational Medicine.

The researchers studied the metabolic consequences of three weeks of sleep restriction (5.6 hours per 24 hours) combined with circadian disruption after a baseline period of optimal sleep (regular bedtimes with 10 hours in bed per 24 hours and normal exposure to daylight) among 21 healthy adult participants.

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Study participants lived in a dimly lit suite for 39 days, without regular time cues. During the first five days,  participants spent 16 hours in bed sleeping as much as they liked, followed by a three week period, during which sleep was restricted to 5.6 hours per 24 hours.

The last phase of the study consisted of a nine day recovery period, during which study participants had a regular bedtime and were allowed 10 hours in bed every 24 hours.

Body weight, resting metabolic rate and metabolic responses to a standardized meal were measured after each period. The researchers found that sleep restriction and circadian disruption led to a lower resting metabolic rate. This was also associated with increased plasma glucose concentrations after meals, which was due to a 32% drop in pancreatic insulin secretion.

“Thus, in humans, prolonged sleep restriction with concurrent circadian disruption alters metabolism and could increase the risk of obesity and diabetes,” the researchers concluded.

Metabolic parameters normalized after participants underwent the nine day “circadian re-intrainment” period, they noted.

Several researchers disclosed financial ties to the pharmaceutical, publishing and medical technology industries; one author has served as an expert witness in a legal case involving sleep, circadian rhythms and diabetes.

Buxton OM et al. Sci Transl Med. 2012; (4)129ra43.