Beneficial impact of sleep extension on fasting insulin sensitivity in adults with habitual sleep restriction

Abstract

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).

Interventions: 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.

Keywords: QUICKI; fasting glucose; fasting insulin; insulin resistance; insulin sensitivity; sleep extension; sleep loss; time in bed; type 2 diabetes.

Figure 1

Total sleep time from actigraphic data. Minutes of total sleep time (+SD) derived from actigraphic data, averaged over the 2 weeks of habitual time in bed and by 3 blocks of 2 weeks during the intervention period. Data are presented for weekdays (left) and weekends (right). *P < 0.0001.

Figure 2

Sleep variables from polysomnographic data. Mean (+SD) total sleep time, intra-sleep awakenings, stage N1, stage N2, stage N3, and REM sleep (in minutes) obtained during one unattended home polysomnography towards the end of the habitual time in bed condition, after 12 days of habitual time in bed (white bars), and one toward the end of the intervention period, after 40 days of sleep extension (black bars). *P < 0.04.

Figure 3A

Percent changes in sleep variables and in fasting glucose and insulin. Associations between the percent changes between pre- and post-intervention in total sleep time and stage N2, and the percent changes between pre- and post-intervention in fasting glucose and insulin.

Figure 3B

Percent changes in sleep variables and in fasting glucose and insulin. Associations between pre- and post-intervention percent changes in total sleep time and stage N2, and those in HOMA, insulin-to-glucose ratio, and QUICKI.