Continuous recording of autonomic nervous activity at nighttime effectively explains subjective sleep reports in postmenopausal women

To investigate the effect of nocturnal autonomic nervous activity on subjective sleep reports, a combined recording using an actigraph and a wristwatch-type pulse wave sensor was carried out. The participants included 19 healthy menopausal women (mean age: 57.3 ± 3.85 years) without menopausal syndrome. Total sleep time (TST) and wake time after sleep onset (WASO) data were acquired from the actigraph. Indices of parasympathetic and sympathetic nervous activity (high frequency [HF] and percentile of low frequency [%LF]) during sleep were calculated by the pulse frequency demodulation method. Subsequently, we investigated the correlations between the averaged values and the subjective report (OSA-MA) scores that were obtained on waking. The strong relationship between the subjective sleep reports on waking and the indices of actigram and pulse rate variability was demonstrated by a positive correlation between the subjective feeling of refreshment and HF during sleep. Therefore, vagal nerve activities could serve as a simple and useful indicator for evaluating subjective sleep quality which is difficult to detect from polysomnography or actigraphy in postmenopausal women.