It is well recognized that sleep loss is associated with deleterious consequences on health. In particular, short sleep duration decreases insulin sensitivity and therefore increases the risk to develop diabetes. It is however not known if the reverse intervention, i.e. sleep extension, could benefit glucose metabolism and reduce diabetes risk. Rachel Leproult and her colleagues have tested this hypothesis in a sleep extension study published in the last issue of the leading international journal Sleep, an article highlighted with an editorial in the same issue.
The authors investigated whether sleep extension is feasible under real-life conditions with a beneficial impact on glucose metabolism in healthy adults who are chronically sleep restricted. Sixteen healthy non-obese volunteers who were chronically sleep restricted were recruited. They first followed their habitual time in bed for two weeks (6 hours per weekdays and more than 7 hours during weekends, on average). They were then instructed to increase their bedtimes by one hour per day for 6 weeks while following the sleep hygiene guidelines. Insulin sensitivity was evaluated at the end of the 2-week habitual time in bed and at the end of the 6-week intervention of sleep extension.
Despite large inter-individual differences, total sleep time during weekdays increased by about 45 minutes without any significant change during weekends. Moreover, the participants who increased their sleep time the most were also those who improved their insulin sensitivity.
This study therefore demonstrates, for the first time, that habitually sleep restricted adults are able to increase their sleep time with, despite modest changes in sleep time, beneficial consequences on insulin sensitivity, and therefore on diabetes risk. Altogether, these findings suggest that sleep should be more systematically assessed in pre-diabetic and diabetic populations, in addition to the common recommendations targeting weight loss and physical activity.
Rachel Leproult, Gaétane Deliens, Médhi Gilson and Philippe Peigneux (2015) Beneficial Impact of Sleep Extension on Fasting Insulin Sensitivity in Adults with Habitual Sleep Restriction. Sleep 38(5): 707-715
Andrea M Spaeth (2015) Additional Sleep Duration Associates with Improved Blood Sugar Regulation. Sleep 38(5): 663-664