Authors: Kazue OkamotoMizuno Kazuyo Tsuzuki Koh Mizuno Yasushi Ohshiro
Publish Date: 2008/10/21
Volume: 105, Issue: 2, Pages: 191-
Abstract
The effects of cold exposure on heart rate variability HRV during sleep were examined Eight male subjects slept under three different conditions 3°C 50–80 relative humidity RH 3 10°C 50 RH 10 and 17°C 50 RH 17 No significant differences were observed in HRV during rapid eye movement sleep REM and wakefulness The ratio of the low frequency LF to high frequency component HF of HRV LF/HF significantly differed among the conditions during stage 2 and slow wave sleep SWS that decreased as the ambient temperature decreased The normalized LF LF/LF + HF significantly decreased in 3 and 10 than in 17 during SWS In low ambient temperature predominant cardiac parasympathetic activity during stage 2 with no significant difference during REM and wakefulness may cause variations in HRV at transition from stage 2 to REM and wakefulness These results may partly explain the peak in adverse cardiac events during winter
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