「Heart rate variability under acute simulated microgravity during daytime waking state and nocturnal sleep: comparison of horizontal and 6 degrees head-down bed rest」

This study examined the effect of cephalad fluid shift under simulated microgravity on heart rate variability (HRV). Under the condition of cephalad fluid shift, HRV during the daytime did not change, although high frequency components in HRV during sleep stage 2 significantly increased in the latter half of sleep. （微小重力環境で生じる体液の頭部方向への移動が、心拍変動に及ぼす影響について検討した。夜半過ぎの睡眠段階2においてのみ副交感神経活動亢進を示唆する変化が生じた。）
pp.115-120
Mizuno K, Inoue Y, Tanaka H, Komada Y, Shirakawa S

Neurosci Lett