Too Late and Not Enough: School Year Sleep Duration, Timing, and Circadian Misalignment Are Associated with Reduced Insulin Sensitivity in Adolescents with Overweight/Obesity.

Objectives: To examine the relationship between insulin resistance (IR) and sleep/circadian health in overweight/obese adolescents. We hypothesized that insufficient and delayed sleep would be associated with IR in this population.

Study Design: Thirty-one adolescents (mean age, 16.0 ± 1.4 years; 77% female) with body mass index ≥90th percentile for age/sex were recruited from outpatient clinics at a children's hospital. Participants underwent 1 week of objective home sleep monitoring with wrist actigraphy during the academic year. A 3-hour oral glucose tolerance test was conducted, followed by in-laboratory salivary dim-light melatonin sampling every 30-60 minutes from 5 p.m. to noon the next day. Regression analyses between sleep and circadian variables with IR were examined.

Results: Longer sleep time and time in bed on weekends and weekdays and earlier weekday bedtime were significantly associated with better insulin sensitivity. Participants who obtained less than the median duration of sleep per night (6.6 hours) had evidence of IR with compensatory insulin secretion compared with those obtaining ≥6.6 hours of sleep. A wider phase angle between bedtime and melatonin onset, indicating a later circadian timing of sleep onset, was significantly associated with IR.

Conclusions: Short sleep duration, later weekday bedtime, and later circadian timing of sleep were associated with IR in a cohort of adolescents with overweight/obesity during the school year. Further research is needed to better understand the physiology underlying these observations and to evaluate the impact of improved sleep and circadian health on metabolic health in this at-risk population.