Forced desynchrony of circadian rhythms of body temperature and activity in rats

Strijkstra, AM., Meerlo, P. & Beersma, DGM., 1999, In : Chronobiology International. 16, 4, p. 431-440

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The daily rhythm in body temperature is thought to be the result of the direct effects of activity and the effects of an endogenous circadian clock. Forced desynchrony (FD) is a tool used in human circadian rhythm research to disentangle endogenous and activity-related effects on daily rhythms. In the present study, we applied an FD protocol to rats. We subjected 8 rats for 5 days to a 20h forced activity cycle consisting of 10h of forced wakefulness and 10h for rest and sleep. The procedure aimed to introduce a 10h sleep/ 10h wake cycle, which period was different from the endogenous circadian (about 24h) rhythm. Of the variation in the raw body temperature data, 68-77% could be explained by a summation of estimated endogenous circadian cycle and forced activity cycle components of body temperature. Free-running circadian periods of body temperature during FD were similar to free-running periods measured in constant conditions. The applied forced activity cycle reduced clock-related circadian modulation of activity. This reduction of circadian modulation of activity did not affect body temperature. Also, the effects of the forced activity on body temperature were remarkably small.

Original languageEnglish
Pages (from-to)431-440
JournalChronobiology International
Issue number4
Publication statusPublished - 1999


  • circadian rhythmicity, suprachiasmatic nucleus, SCN, forced desynchrony, internal desynchronization, free-running rhythms, radiotelelemtry, body temperature, locomotor activity, sleep

ID: 719455