REM Sleep May Lead to Warm Up Your Brain From The Inside

A new assessment suggests that entering rapid eye movement (REM) sleep may still warm you up from the inside, even if the dreams you have don't include any hot or steamy themes. In the natural world, warm-blooded animals with lower body temperatures typically experience longer REM sleep intervals, whereas warm-blooded animals with higher body temperatures, such as birds, generally experience less REM sleep. Neurologist and famous sleep scientist Jerome Siegel, from the University of California Los Angeles, claims the association is noteworthy and should be investigated further. Siegel puts forth that REM sleep might be sort of "like shivering for the brain" when brain and body temperatures drop too low during non-REM sleep. The brain becomes quite active during REM, which increases the organ's temperature. Furthermore, non-REM sleep, during which the brain and body are the least active and coldest, always comes before REM sleep. "REM sleep might be thought of as a thermostatically controlled brain-heating mechanism, which is triggered by the temperature reduction linked to the reduced metabolism and the decrease in energy consumption in non-REM sleep," writes Siegel. "Then, REM sleep ends after the amount of REM required to raise brain temperature to close to the waking temperature of the body has occurred." In fact, it's possible that this explains why some animals' sleep patterns change from season to season. Hibernation is the most extreme example of that, but even animals that don't hibernate, such Arctic reindeer, sleep 43 percent more in the winter than in the summer. In hunter-gatherer societies, people slept an additional hour or so during the winter. Could REM sleep provide animals with essential rest while also shielding their brains from the cold? Given the shortcomings of earlier REM sleep ideas, Siegel believes it to be entirely plausible.