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As humans fall asleep, body activity slows down. Body temperature, heart rate, breathing rate, and energy use all decrease. Brain waves slow down. The excitatory neurotransmitter acetylcholine becomes less available in the brain. [9] Humans often maneuver to create a thermally friendly environment—for example, by curling up into a ball if cold.
Modern humans often find themselves desynchronized from their internal circadian clock, due to the requirements of work (especially night shifts), long-distance travel, and the influence of universal indoor lighting. [31] Even if they have sleep debt, or feel sleepy, people can have difficulty staying asleep at the peak of their circadian cycle.
Chronic sleep deprivation (less than 8 hours of sleep) is associated with an increase in body mass index (BMI) and obesity. 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 ...
In this podcast episode, Medical News Today shares three actionable resolutions that can help improve brain, heart, and metabolic health in the new year via diet, sleep, and exercise. Brain health ...
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]
Tonic activity of the pharyngeal dilator muscles of the upper airway decreases during the NREM sleep, contributing to the increased resistance, which is reflected in increased esophageal pressure swings during sleep. The other ventilatory muscles compensate for the increased resistance, and so the airflow decreases much less than the increase ...
The sleep study was only conducted over a single night, so the data on sleep duration may not represent long-term sleep patterns. Blood pressure decreases by 10% at the time of sleep onset, and ...
During a night of sleep, humans usually experience about four or five periods of REM sleep; they are shorter (~15 min) at the beginning of the night and longer (~25 min) toward the end. Many animals and some people tend to wake, or experience a period of very light sleep, for a short time immediately after a bout of REM.