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Humans are sensitive to light with a short wavelength. Specifically, melanopsin is sensitive to blue light with a wavelength of approximately 480 nm. [19] The effect this wavelength of light has on melanopsin leads to physiological responses such as the suppression of melatonin production, increased alertness, and alterations to the circadian ...
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 ...
This experiment provided evidence that humans have a circadian clock that can run independently from the 24-hour light-dark cycle and that different people can have unique rhythms. [7] The demonstration of the human circadian clock led to research that uncovered many of the mechanisms that underlie it. [13] Desynchronization observed in this ...
Summary of pervasive effects of light. The SCN of the hypothalamus contains an endogenous pacemaker that regulates circadian rhythms. [4] The zeitgeber found to have the most profound effect on the SCN is light, which is the form of stimulation of which conversion is needed for it to be processed by the brain. Neurotransmitters that travel the ...
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 ...
Part of the basis for siestas and afternoon naps goes back to our body's natural 24-hour, or circadian, rhythm in body temperature. "Body temperature is at its lowest in the middle of the night ...
More recently, light therapy and melatonin administration have been explored by Alfred J. Lewy , Josephine Arendt (University of Surrey, UK) and other researchers as a means to reset animal and human circadian rhythms. Additionally, the presence of low-level light at night accelerates circadian re-entrainment of hamsters of all ages by 50% ...
Czeisler's research interests encompass many areas, including the effects of light on human circadian rhythms, the role of sleep and circadian rhythms in metabolism, the impact of shift work on health and productivity, and the effects of melatonin and melatonin receptor agonists on humans.