The association between sleep parameters, cognitive functioning, and markers of brain morphology: The Maastricht Study.

Study Objectives: To examine the association of objective and subjective sleep parameters with cognitive functioning and markers of brain morphology.

Methods: This cross-sectional study included 3360 participants (mean age: 59.5 ± 8.5 years; 51.1% female) from The Maastricht Study. Time in bed (TIB) and sleep breaks were objectively estimated using a thigh-worn accelerometer. Subjective sleep continuity was assessed via a single-item, and excessive daytime sleepiness was evaluated using the Epworth Sleepiness Scale. Cognitive testing was administered across three domains- memory, information processing speed, and executive functioning and attention. Markers of brain morphology (e.g., hippocampal volume, grey matter (GM) volume and white matter volume) were assessed with 3 Tesla magnetic resonance imaging. Linear and logistic regression analyses modelled the associations.

Results: Longer TIB (h/night) was associated with worse executive functioning and attention (Blinear = -0.052, 95%CI = -0.084 to -0.019). Categorical analyses showed that a longer TIB (≥9 h/night) was associated with worse executive functioning and attention (B = -0.088, 95%CI = -0.166 to -0.010) compared to a mid-range TIB (≥7 to <9 h/night). A curvilinear association was found between TIB and lower GM volume (Bquadratic = -0.013, 95%CI = - 0.025 to -0.001). Sleep breaks (≥2/night) were associated with worse overall cognition (B = -0.069, 95%CI = -0.124 to -0.013), information processing speed (B = -0.125, 95%CI = -0.212 to -0.039), and reduced GM volume (B = -0.068, 95%CI = -0.118 to -0.018). No significant associations were found for memory or other markers of brain morphology. Subjective sleep parameters showed no associations with cognitive functioning or markers of brain morphology.

Conclusions: Adequate and uninterrupted TIB was associated with better cognitive functioning and brain morphology.