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Sleep cycle. 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]
During sleep, most of the body's systems are in an anabolic state, helping to restore the immune, nervous, skeletal, and muscular systems; [3] these are vital processes that maintain mood, memory, and cognitive function, and play a large role in the function of the endocrine and immune systems. [4]
Polyphasic sleep is the practice of sleeping during multiple periods over the course of 24 hours, in contrast to monophasic sleep, which is one period of sleep within 24 hours. Biphasic (or diphasic, bifurcated, or bimodal) sleep refers to two periods, while polyphasic usually means more than two. [ 1 ]Segmented sleep and divided sleep may ...
Sleep deprivation was also found to increase beliefs of being correct, especially if they were wrong. Another study reported that the performance on free recall of a list of nouns is significantly worse when sleep deprived (an average of 2.8 ± 2 words) compared to having a normal night of sleep (4.7 ± 4 words).
Young woman asleep over study materials. The relationship between sleep and memory has been studied since at least the early 19th century.Memory, the cognitive process of storing and retrieving past experiences, learning and recognition, [1] is a product of brain plasticity, the structural changes within synapses that create associations between stimuli.
Though variation is great among normal chronotypes, the average human adult's temperature reaches its minimum at about 5:00 a.m., about two hours before habitual wake time. Baehr et al. [ 91 ] found that, in young adults, the daily body temperature minimum occurred at about 04:00 (4 a.m.) for morning types, but at about 06:00 (6 a.m.) for ...
In a study with 3000 patients, it was found that men and women who sleep less than 5 hours have elevated body mass index (BMI). In another study that followed about 70.000 women for 16 years, there was a significant increase in body weight in those who slept 5 hours or less compared to those who slept 7–8 hours. [1] [2] [8]
Chronotype. A chronotype is the behavioral manifestation of underlying circadian rhythm 's myriad of physical processes. A person's chronotype is the propensity for the individual to sleep at a particular time during a 24-hour period. Eveningness (delayed sleep period; most active and alert in the evening) and morningness (advanced sleep period ...