Characterisation of cyclic alternating pattern during sleep in older men and women using large population studies

STUDY OBJECTIVES: To assess the microstructural architecture of non-rapid eye movement (NREM) sleep known as cyclic alternating pattern (CAP) in relation to the age, gender, subjective sleep quality and the degree of sleep disruption in large community-based cohort studies of older people. METHODS: We applied a high performance automated CAP detection system to characterise CAP in 2,811 men from the Osteoporotic Fractures in Men Sleep Study (MrOS) and 426 women from the Study of Osteoporotic Fractures Sleep Study (SOF). CAP was assessed with respect to age and gender and correlated to obstructive apnea-hypopnea index (OAHI), arousal index (AI-NREM) and periodic limb movements in sleep index (PLMSI). Further, we evaluated CAP across levels of subjective sleep quality measures using analysis of covariance. RESULTS: Age was significantly associated with the number of CAP sequences during NREM sleep (MrOS: p = 0.013, SOF = 0.051). CAP correlated significantly with AI-NREM (MrOS: rho = 0.30, SOF: rho = 0.29). CAP rate, especially the A2+A3 index, was inversely related to subjectively reported quality of sleep, independent of age and sleep disturbance measures. Women experienced significantly fewer A1-phases compared to men, in particular in slow wave sleep (N3). CONCLUSIONS: We demonstrate that automated CAP analysis of large-scaled databases can lead to new findings on CAP and its subcomponents. We show that sleep disturbance indices are associated with CAP rate. Further, CAP rate is significantly linked to subjectively reported sleep quality, independent from traditionally scored markers of sleep fragmentation. Finally, men and women show differences in the micro-architecture of sleep as identified by CAP, despite similar macro-architecture.