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Recently, ultradian rhythms of arousal lasting approximately 4 hours were attributed to the dopaminergic system in mammals. [5] When the dopaminergic system is perturbed either by use of drugs or by genetic disruption, these 4-hour rhythms can lengthen significantly into the infradian (> 24 h) range, sometimes even lasting for days (> 110 h ...
Empirically, it is an ultradian rhythm of approximately 90 minutes (80–120 minutes [2]) characterized by different levels of excitement and rest. The cycle is mediated by the human biological clock .
Kleitman and others following have referred to this rhythm as the basic rest–activity cycle, of which the "sleep cycle" would be a manifestation. [ 14 ] [ 19 ] A difficulty for this theory is the fact that a long non-REM phase almost always precedes REM, regardless of when in the cycle a person falls asleep.
A zeitgeber (/ ˈ (t) s aɪ t ɡ eɪ b ər, ˈ z aɪ t-/ (T)SYTE-gay-bər, ZYTE-, German: [ˈtsaɪtˌɡeːbɐ]) is any external or environmental cue that entrains or synchronizes an organism's biological rhythms, usually naturally occurring and serving to entrain to the Earth's 24-hour light/dark and 12-month cycles.
The best studied rhythm in chronobiology is the circadian rhythm, a roughly 24-hour cycle shown by physiological processes in all these organisms. The term circadian comes from the Latin circa, meaning "around" and dies, "day", meaning "approximately a day." It is regulated by circadian clocks.
Ultradian rhythms, which are cycles shorter than 24 hours, such as the 90-minute REM cycle, the 4-hour nasal cycle, or the 3-hour cycle of growth hormone production. Tidal rhythms, commonly observed in marine life, which follow the roughly 12.4-hour transition from high to low tide and back. Lunar rhythms, which follow the lunar month (29.5 ...
The oldest quantitative laws in psychology are Weber's law, which states that the smallest noticeable difference in stimulus intensity is proportional to the intensity of the reference; and Fechner's law, which quantifies the relationship between the intensity of the physical stimulus and its perceptual counterpart (e.g., testing how much ...
Free-running sleep is a rare sleep pattern whereby the sleep schedule of a person shifts later every day. [1] It occurs as the sleep disorder non-24-hour sleep–wake disorder or artificially as part of experiments used in the study of circadian rhythms and other rhythms in biology .