Changes in Cardiopulmonary Coupling During Sleep Onset

The cardiopulmonary coupling measure has been proposed recently as an indicator of sleep stability. We examined changes in cardiopulmonary coupling during the sleep onset period and its usefulness in estimating sleep onset. Overnight polysomnography data from 10 male adults without sleep disordered breathing was analysed (age 40 plusmn 7 years, BMI 31 plusmn 3 kg/m², AHI 0.9 plusmn 0.9 hr^-1). Results suggest that cardiopulmonary coupling typical of unstable sleep was associated with phases of wakefulness and awakening. Sleep onset latency was estimated with an average error of 9 mins. In conclusion, cardiopulmonary coupling is able to provide statistical trends with respect to the sleep onset period, and is also useful in pinpointing sleep onset.