Evidence for a biological dawn and dusk in the human circadian timing system
| العنوان: | Evidence for a biological dawn and dusk in the human circadian timing system |
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| المؤلفون: | Daniel Aeschbach, Wallace C. Duncan, Thomas A. Wehr |
| المصدر: | The Journal of Physiology. 535:937-951 |
| بيانات النشر: | Wiley, 2001. |
| سنة النشر: | 2001 |
| مصطلحات موضوعية: | Hydrocortisone, Physiology, Photoperiod, Polysomnography, Timing system, Radioimmunoassay, Sleep, REM, Dusk, Environment, Biology, Nocturnal, Body Temperature, Rhythm, Humans, Circadian rhythm, Melatonin, Circadian pacemaker, Communication, business.industry, digestive, oral, and skin physiology, Electroencephalography, Original Articles, Bacterial circadian rhythms, Circadian Rhythm, Light effects on circadian rhythm, sense organs, Sleep Stages, business, Neuroscience |
| الوصف: | Sometimes, investigators who study human circadian physiology use sine functions to model circadian rhythms, as if they were inherently continuous and sinusoidal. Many investigators, however, recognize that human circadian rhythms exhibit discontinuous changes and seem to be governed by multiple processes that require more complex models and methods of analysis. In this regard, a series of observations in our laboratory led us to propose a specific model for the human circadian system in which two states, one diurnal and one nocturnal, alternate with one another, and in which transitions between the states are switch-like and are separately entrained to dawn and dusk. Although circadian rhythms are generated within the organism and persist in the absence of external input, it is obvious that the temporal programme outlined above mirrors the contours of the external day-night cycle, in effect creating a ‘day within’ (Pittendrigh, 1988). This parallel has obvious functional implications. It seems likely that this programme enables humans to anticipate and to adapt automatically to the contrasting conditions of their daytime and night-time worlds (Rusak, 1989). This interpretation is consistent with the fact that the circadian pacemaker entrains the transitions between diurnal and nocturnal states to dawn and dusk, and the fact that it can adjust the length of the interval between these transitions to accommodate seasonal changes in day length (Pittendrigh & Daan, 1976; Illnerova & Vanecek, 1982; Wehr et al. 1993; Elliott & Tamarkin, 1994). Conceptually, this model of the human circadian system is similar to the classic Pittendrigh-Daan model of the rodent circadian system (Pittendrigh & Daan, 1976). In rodents, the model appears to describe the behaviour of processes that take place in the circadian pacemaker itself, in addition to the rhythms that the pacemaker regulates (Sumova et al. 1995; Mrugala et al. 2000). Although these processes cannot be measured directly in humans, the observations in rodents suggest that the temporal organization of overt rhythms in humans is likely to reflect the temporal organization of processes that take place in their pacemaker, too. |
| تدمد: | 1469-7793 0022-3751 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::f9bd8e91f5b9c79fd1cd15b99d50eb18 https://doi.org/10.1111/j.1469-7793.2001.t01-1-00937.x |
| حقوق: | OPEN |
| رقم الأكسشن: | edsair.doi.dedup.....f9bd8e91f5b9c79fd1cd15b99d50eb18 |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 14697793 00223751 |
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