Association between individual impairments in glucose metabolism and cognitive performance in response to sleep restriction

Kurzfassung

Introduction: Short sleep durations have been associated with impaired glucose metabolism as well as with trait-like impairments in cognitive functions. We examined whether this trait vulnerability of cognitive performance to sleep loss extends also to glucose tolerance and insulin sensitivity. Methods: Thirty-six healthy volunteers underwent a 12-day sleep lab study. In a sequential design, they completed one adaptation night and two baseline nights with 8 h time in bed (TIB), 5 nights with 5 h TIB (21 participants of the sleep restriction group, 9 female, mean ± SD, age 26 ± 4 yrs, BMI 23.1 ± 1.9) or 5 nights with 8 h TIB (control group, data not shown here), followed by one 8 h TIB recovery night, 38 h of sleep deprivation, and a final night with 10 h TIB. Oral glucose tolerance was tested in the morning immediately after lights on (>10 h fasting) on the second baseline day, after 5 nights with 5 h or 8 h TIB, after the recovery night, and after 24 h of sustained wakefulness. Fasting glucose and insulin levels, as well as those 30, 60, 90, and 120 min after glucose intake were analyzed in blood samples. Averaged daytime results of a 3-hourly performed psychomotor vigilance task (10-min PVT) were calculated. Pearson correlations between impairments (differences to baseline) in glucose metabolism and performance were calculated. Results: Mixed ANOVAs showed that in comparison to baseline areas under the curve (AUC) of glucose, insulin, and the homeostasis model assessment (HOMA) were increased after sleep restriction (all p=0.0003), stayed elevated after one night of recovery sleep (all p<0.02), but returned to baseline levels after 24 h of sleep deprivation (all p>0.6). Impairments after 5 nights of sleep restriction showed significant correlations between mean speed/10th percentile of speed and glucose at 90 min (r=-0.51/r=-0.52), insulin at 30 min (r=-0.55/r=-0.59), 90 min (r=-0.61/-0.61), and at 120 min (r=-0.51/trend r=-0.49) after exposure. Conclusion: Sleep restriction, but not acute sleep deprivation, impaired glucose tolerance and insulin sensitivity. Individuals under sleep restriction appeared to be likewise either vulnerable or resilient regarding both glucose metabolism and cognitive performance.