Over the past several years, adequate sleep has been associated with appetite suppression, weight loss and improved energy levels. New research suggests that 8 hours of nightly shuteye may also protect against type 2 diabetes.
The goal of the study, published in Diabetologia (2015; doi: 10.1007/s00125-015-3500-4), was to determine what link—if any—existed between sleep restriction and the alteration of hormones that regulate the breakdown of fats into fatty acids and glycerol. Researchers recruited 19 men, aged 18–30, and assigned each of them to either 4.5 hours or 8.5 hours of sleep per night for 4 nights. The scientists assessed nonesterified (i.e., free) fatty acid (NEFA) concentrations, and growth hormone, noradrenaline, cortisol, glucose and insulin levels in each of the men.
According to the data, those in the sleep restriction group experienced an increase in NEFA levels at night and in the early morning. They had prolonged nighttime growth hormone secretion and higher early-morning noradrenaline levels, as well as reduced insulin sensitivity, compared with the normal sleep group.
“Sleep restriction in healthy men results in increased nocturnal and early-morning NEFA levels, which may partly contribute to insulin resistance and the elevated diabetes risk associated with sleep loss,” the authors warned.