Seasonal variation in the human circadian rhythm: dissociation between sleep and temperature rhythm.

摘要: The circadian rhythms of sleep-wakefulness, rectal temperature, and plasma melatonin were measured in 10 healthy male subjects for five consecutive seasons. To minimize direct effects seasonally changing environmental factors, the stayed a living facility 4 days each season, where ambient humidity, social contacts controlled, while light intensity room was substantially influenced by natural daylight. Seasonal variations found timing sleep, mean body phases temperature rhythms, phase relation between sleep rhythm. went to bed earliest summer, intermediate spring autumn, latest winter. A similar but more pronounced seasonality observed wake-up time, which earlier summer than acrophases calculated fitting cosine curve, located an time day phase-angle difference rhythm varied positive These findings indicate that not only external (to local time) also internal (between rhythms) relations human depend on season.