BMI, Sleep Architecture, and Glucose Metabolism: Insights From the Baependi Heart Study.

OBJECTIVE

To examine whether (1) sleep architecture is associated with BMI groups in the absence of sleep apnea and (2) BMI group modified associations between sleep architecture and markers of glucose metabolism.

METHODS

The Baependi Heart Study (BHS) is a family-based observational study of adults that assessed sleep using at-home polysomnography (PSG) and collected anthropometric and fasting blood measures. BMI was classified into: 18.5 to < 25, 25 to < 30, and ≥ 30 kg/m2. People with moderate-severe sleep apnea and taking diabetes-related medication were excluded. Cross-sectional associations were examined (n = 1014).

RESULTS

Individuals with BMI ≥ 30 kg/m2 had less REM sleep (-7.8 min, p = 0.003) and the groups with BMI 25 to < 30 kg/m2 and ≥ 30 kg/m2 had higher apnea-hypopnea index than individuals with BMI 18.5 to < 25 kg/m2 (by 0.8 and 1.4 events per hour, respectively, p < =0.002). Wake after sleep onset (WASO) was associated with higher fasting glucose levels in participants with BMI ≥ 30 kg/m2 only; 10 min more WASO was associated with ~1% higher fasting glucose (p = 0.002).

CONCLUSIONS

After exclusion of participants with moderate-severe sleep apnea, there was no difference in non-REM sleep and only a small difference in REM sleep between BMI groups, suggesting that BMI does not substantially impair sleep unless sleep apnea is present.