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Although circadian rhythms are endogenous, they are adjusted to the local environment by external cues called zeitgebers (from German Zeitgeber (German: [ˈtsaɪtˌɡeːbɐ]; lit. ' time giver ')), which include light, temperature and redox cycles. In clinical settings, an abnormal circadian rhythm in humans is known as a circadian rhythm sleep ...
A circadian rhythm is an entrainable, endogenous, biological activity that has a period of roughly twenty-four hours. This internal time-keeping mechanism is centralized in the suprachiasmatic nucleus (SCN) of humans, and allows for the internal physiological mechanisms underlying sleep and alertness to become synchronized to external environmental cues, like the light-dark cycle. [4]
The sleep diary, or sleep log, is a tool used by doctors and patients. [1] [2] [3] It is a useful resource in the diagnosis and treatment of especially circadian rhythm sleep disorders, and in monitoring whether treatment of those and other sleep disorders is successful. Sleep diaries may be used in conjunction with actigraphy.
Consenting relatives of the initial patient were evaluated, as well as those from two additional families. The clinical histories, sleep logs and actigraphy patterns of subject families were used to define a hereditary circadian rhythm variant associated with a short endogenous (i.e. internally-derived) period. The subjects demonstrated a phase ...
Because circadian clocks synchronize human sleep-wake cycles to coincide with periods of the day during which reward potential is highest – that is, during the daytime [16] – and recent studies have determined that daily rhythms in reward activation in humans are modulated by circadian clocks as well, [16] external influences on those ...
Complaints of non-restorative sleep without troubles of initiating or maintaining sleep are excluded. These difficulties are not primarily caused by a circadian rhythm disorder. In the case of a circadian rhythm disorder treatments such as phototherapy or chronobiologic interventions might be more suitable. However many primary insomnia ...
In chronobiology, a circasemidian rhythm is a physiological arousal cycle that peaks twice in a 24-hour day. It may also be called the semicircadian rhythm . Numerous studies have demonstrated that human circadian rhythms in many measures of performance and physiological activity have a 2-peak daily (circasemidian) pattern. [ 1 ]
The activity/rest cycle (sleep) in animals is one of the circadian rhythms that normally are entrained by environmental cues. In mammals, such endogenous rhythms are generated by the suprachiasmatic nucleus (SCN) of the anterior hypothalamus. Entrainment is accomplished by altering the concentration of clock components through altered gene ...