Instituto de Psicologia, Universidade de São Paulo, São Paulo, Brazil.
Physiol Behav. 2012 Feb 1;105(3):613-20. doi: 10.1016/j.physbeh.2011.10.006. Epub 2011 Oct 12.
Access to electricity, granting relative independence of human activity on the dark phase of the day, has been pointed out as an important cause for the absence of seasonal changes in the daily rhythms of humans living in urban areas. Featuring a population of adult Guarani natives living without access to electricity, the present naturalistic study was designed to explore possible effects of different natural photoperiods and temperature on human circadian rhythms. We compared time series of wrist temperature (WT) and motor activity in winter and summer, respectively, of 24 individuals aged 18 to 80. Twenty-four-hour rhythms of WT showed lower amplitudes and higher mean levels in summer, with no significant seasonal differences in acrophase. In contrast, rest-activity (RA) rhythms exhibited a significantly later rest on- and offset in summer, but no seasonal changes in duration, amplitude and mean level. We furthermore identified a phase advance of both the WT acrophase and rest onset with increasing age of the individuals. We concluded that in our study the effect of different seasons was reflected in the amplitude and mean level of the WT rhythm, as well the onset of nighttime rest, which was delayed in summer.
电力的供应，使人类在白天的黑暗阶段相对独立，这被认为是城市居民的日常节律中没有季节性变化的重要原因。本自然主义研究的特点是有一群成年瓜拉尼原住民生活在没有电力供应的情况下，旨在探索不同自然光照时间和温度对人类昼夜节律的可能影响。我们比较了 24 名年龄在 18 岁至 80 岁之间的个体在冬季和夏季的腕温（WT）和运动活动的时间序列。WT 的 24 小时节律在夏季的幅度较低，平均水平较高，相位没有明显的季节性差异。相比之下，休息-活动（RA）节律在夏季的休息开始和结束时间明显较晚，但持续时间、幅度和平均水平没有季节性变化。此外，我们还发现，WT 的相位和休息开始时间随着个体年龄的增长而提前。我们得出的结论是，在我们的研究中，不同季节的影响反映在 WT 节律的幅度和平均水平上，以及夜间休息的开始时间上，夏季休息开始时间延迟。
