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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 .
The sleep cycle is an oscillation between the slow-wave and REM (paradoxical) phases of sleep. 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]
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.
Then those cycles are broken into stages within two categories: NREM sleep (non-rapid eye movement sleep) and REM sleep (also known as rapid eye movement sleep). Your brain activity changes during ...
Sedentary adults over age 55 show a 1–2% decline in hippocampal volume annually. [37] A neuroimaging study with a sample of 120 adults revealed that participating in regular aerobic exercise increased the volume of the left hippocampus by 2.12% and the right hippocampus by 1.97% over a one-year period. [37]
Free-running organisms that normally have one or two consolidated sleep episodes will still have them when in an environment shielded from external cues, but the rhythm is not entrained to the 24-hour light–dark cycle in nature. The sleep–wake rhythm may, in these circumstances, become out of phase with other circadian or ultradian rhythms ...
Running can improve mental alertness and sleep. [69] Both research and clinical experience have shown that exercise can be a treatment for serious depression and anxiety even some physicians prescribe exercise to most of their patients. [70] Running can have a longer-lasting effect than anti-depressants. [71]
These shifts do not align with the natural light–dark cycle. Non-24-hour sleep–wake disorder causes a person's sleep–wake cycle to move around the clock every day, to a degree dependent on the length of the cycle. This is known as free-running sleep. [citation needed]