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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 ...
The basic rest–activity cycle (BRAC) is a physiological arousal mechanism in humans proposed by Nathaniel Kleitman, [1] hypothesized to occur during both sleep and wakefulness. Empirically, it is an ultradian rhythm of approximately 90 minutes (80–120 minutes [ 2 ] ) characterized by different levels of excitement and rest.
It is sometimes called the ultradian sleep cycle, sleep–dream cycle, or REM-NREM cycle, to distinguish it from the circadian alternation between sleep and wakefulness. In humans, this cycle takes 70 to 110 minutes (90 ± 20 minutes). [1] Within the sleep of adults and infants there are cyclic fluctuations between quiet and active sleep.
Overview, including some physiological parameters, of the human circadian rhythm ("biological clock"). Chronobiology is a field of biology that examines timing processes, including periodic (cyclic) phenomena in living organisms, such as their adaptation to solar- and lunar-related rhythms. [1] These cycles are known as biological rhythms.
"The word 'siesta' comes from the Latin 'sexta,' meaning the sixth hour after someone wakes up," says Dr. Dylan Petkus, MD, MPH, a sleep researcher with Optimal Circadian Health. For example, he ...
By regulating social rhythms, therapists hope to normalize in turn individuals' biological rhythms. Studies have not found much evidence that IPSRT improves mood, but individuals undergoing IPSRT experience longer periods between bipolar episodes, indicating that normalizing social rhythms may have a preventative effect.
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 ...
These rhythms are influenced by variable environmental cues, and in some species are influenced by internal cues. In a study conducted by Catalina Reyes, the authors took a further look into how red-eared sliders showed circadian and circannual rhythms in metabolism, and if metabolic rates overall influenced the circadian and circannual cues.