Sep 21, 2022 23:00:00

The possibility that REM sleep exists to 'warm the brain'

Sleep consists of

REM sleep and non -REM sleep. In REM sleep, the brain is in an awake state while sleeping, and rapid eye movements occur. It is said that such REM sleep has the role of `` strengthening memory and learning '', but a new hypothesis that `` REM sleep exists to warm the brain '' was proposed.

Sleep function: an evolutionary perspective - The Lancet Neurology
https://doi.org/10.1016/S1474-4422(22)00210-1

REM Sleep May Exist to Heat Your Brain Up From The Inside : ScienceAlert
https://www.sciencealert.com/rem-sleep-may-exist-to-heat-your-brain-up-from-the-inside

Sleep patterns that alternate between REM sleep and non-REM sleep are mainly found in birds and mammals, but in recent years, research results have been reported that similar sleep patterns exist in fish and reptiles . Also, although it was once said that ``dreams only occur during REM sleep,'' it is actually known that even during non-REM sleep, you are dreaming in a different pattern than during REM sleep .

In general, the prevailing hypothesis is that NREM sleep has the role of removing toxins from the brain , and that REM sleep has the role of consolidating what has been learned by consolidating memories . However, Jerome Siegel, a sleep scientist at the University of California, Los Angeles, has proposed the hypothesis that REM sleep exists to warm the brain.

Siegel points out that in the natural world, ``

homeothermic animals with lower body temperatures spend more time in REM sleep, while birds with higher body temperatures generally spend less time in REM sleep.'' In addition, reindeer living in the Arctic sleep 43% longer in winter than in summer, and people in hunter-gatherer societies sleep about an hour longer in the cold season.

Siegel, who focused on the relationship between body temperature and REM sleep, argued that REM sleep is 'like shaking the brain' and may exist to warm the brain that has fallen too much during non-REM sleep. I'm here. In fact, during REM sleep, the brain becomes active and the temperature rises.

``REM sleep may be thought of as a thermostat -controlled brain-warming mechanism caused by the hypothermia associated with decreased metabolism and reduced energy expenditure during non-REM sleep,'' Siegel said. 'Sleep ends after the brain temperature rises close to waking body temperature.'

In addition, Mr. Siegel points out that there are questions about the conventional hypothesis that 'REM sleep plays a role in consolidating memory and learning.' Activating the brain in REM sleep after shedding toxins in non-REM sleep may be somewhat absurd, arguing that there is no clear link between REM sleep and cognitive performance.

As an example that casts doubt on the relationship between REM sleep and cognitive ability, Mr. Siegel cites the

fact that `` Platypus REM sleep is longer than any animal, including humans, and sleeps up to 8 hours a day.'' . Indeed, the claim that platypus needs up to 8 hours of REM sleep for memory and learning may be somewhat painful. However, given that the Monotreme , to which the platypus belongs, has both mammalian and reptile characteristics and is imperfectly homeothermic and less able to regulate body temperature, it is suggested that 'the platypus needs more energy to maintain brain temperature during sleep.' It is said that persuasiveness is born in the hypothesis that REM sleep is required.

On the other hand, mammals that do not show signs of REM sleep include dolphins. Since dolphins have hemispheric sleep in which only half of the brain sleeps alternately, Mr. Siegel speculates that it is not necessary to raise the brain temperature in REM sleep because one brain plays the role of 'heater'. doing.