190-m Heliox 해상 포화잠수에서의 수면패턴과 하루주기리듬

Abstract

The purpose of this study is to examine sleep structure and circadian rhythmicity under the hyperbaric environment to obtain fundamental data so that a desirable sleep environment for divers may be organized using actigraphy. The total sleep time(TST), sleep period time(SPT), sleep efficiency(SE), sleep latency(SL), wake after sleep onset(WASO), number of awakenings(NA), length of daytime naps(LDN), and number of daytime naps(NDN) for 5 divers were measured over a period of 55 nights under a He O₂ open-sea hyperbaric saturation dive to 20 ATA with excursions to 21 ATA. The results of the one-way ANOVA, among the experimental days, showed significant effects in TST, SPT, SE, SL, LDN, and NDN. TST and SPT were significantly shortened in the bottom and decompression periods as opposed to the pre-dive period. SE showed the same tendency as TST. SL increased significantly from the bottom period through to the decompression period. WASO and NA with the LDN and NDN increased in the bottom and decompression periods. Individual time series were analyzed according to several statistical methods(autocorrelation function, Fast Fourier transform(FFT), and power spectrum analysis(PSA)) using wrist actigraphy, in order to estimate the prominent circadian period(tau = 24-h) and to evaluate each days differences. The autocorrelation function for the time series of each day showed significant circadian rhythmicity with circasemidian rhythmicity(tau = about 12-h) except the 1st day of the bottom period. The PSA for the time series of each day showed significant, about 25-h circadian rhythmicity with circasemidian rhythmicity, on the 1st, 2nd, and 5th days of the decompression period. The 2nd day of the bottom period showed a significant circadian rhythmicity with circasemidian rhythmicity, about 26-h. However, the remainder also showed significant circadian rhythmicity with circasemidian rhythmicity, about 24-h. The results of FFT showed similar changes to the autocorrelation function.