Effect of sleep stage on the relationship between respiration and heart rate variability

The effect of the sleep stage on the cardiorespiratory relationship in five patients with sleep apnea syndrome is studied. Initially developed was a polysomnographic data management system. Polysomnographic data are digitally stored totally on a hard disk. The stored data were rapidly retrieved, displayed on a CRT screen and analyzed quantitatively and semiautomatically by a screen editor. A period of regular breathing was selected in each sleep stage. The high-frequency band of power spectrum of heart rate variability decreased significantly during rapid eye movement (REM) sleep. The RR-interval was shorter during REM sleep than during non-REM (NREM) sleep. It is concluded that the cardiorespiratory relationship is modulated by sleep stage during periods of regular breathing. It is speculated that this is due to decreased efferent parasympathetic activity during REM sleep compared to NREM sleep.<
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