Beneficial Impact of Sleep Extension on Fasting Insulin Sensitivity in Adults with Habitual Sleep Restriction

Study Objectives: A link between sleep loss and increased risk for the development of diabetes is now well recognized. The current study investigates whether sleep extension under real-life conditions is a feasible intervention with a beneficial impact on glucose metabolism in healthy adults who are chronically sleep restricted. Design: Intervention study. Participants: Sixteen healthy non-obese volunteers (25 [23, 27.8] years old, 3 men). Intervention: Two weeks of habitual time in bed followed by 6 weeks during which participants were instructed to increase their time in bed by one hour per day. Measurements and Results: Continuous actigraphy monitoring and daily sleep logs during the entire study. Glucose and insulin were assayed on a single morning blood sample at the end of habitual time in bed and at the end of sleep extension. Home polysomnography was performed during one weekday of habitual time in bed and after 40 days of sleep extension. Sleep time during weekdays increased (mean actigraphic data: +44 +/- 34 minutes, P < 0.0001; polysomnographic data: +49 +/- 68 minutes, P = 0.014), without any significant change during weekends. Changes from habitual time in bed to the end of the intervention in total sleep time correlated with changes in glucose (r = +0.53, P = 0.041) and insulin levels (r = -0.60, P = 0.025), as well as with indices of insulin sensitivity (r = +0.76, P = 0.002). Conclusions: In healthy adults who are chronically sleep restricted, a simple low cost intervention such as sleep extension is feasible and is associated with improvements in fasting insulin sensitivity.