Summary: Studies have shown that warm-blooded animals with higher body temperatures have less REM sleep, while those with lower body temperatures have more REM sleep. Researchers say REM sleep is like “temperature-controlled brain warming.”
Groups of warm-blooded animals with higher body temperatures have less rapid eye movement (REM) sleep, while those with lower body temperatures have more REM sleep, according to a new study by UCLA professor Jerome Siegel. It works like a “thermostatically controlled brain heater”.
The study by Lancet Neurology Siegel, who directs the Jane and Terry Semel Sleep Research Center at UCLA, points to a previously unseen link between body temperature and REM sleep.
Birds have the highest body temperature of any warm-blooded or hormosomal animal group at 41 degrees Celsius, with only 0.7 hours of REM sleep per day. That’s followed by humans and other placental mammals (37 degrees, 2 hours of REM sleep), marsupials (35 degrees, 4.4 hours of REM sleep), and monotremes (31 degrees, 7.5 hours of REM sleep).
Brain temperature falls during non-REM sleep and then normally rises during the following REM sleep. This pattern “allows homeotherm mammals to conserve energy during non-REM sleep when the brain is so cold that it doesn’t respond to danger,” Siegel said.
Humans’ rates of REM sleep are neither higher nor lower than those of other hormonal animals, he says, “disrupting some popular views suggesting a role for REM sleep in learning or emotional regulation.”
Financial support Siegel’s research is supported by grants from the National Institutes of Health (HLB148574 and DA034748) and the Department of Veterans Affairs Medical Research Service. He declared that he was not interested in competing.
So sleep research news
Author: Jason Millman.
Contact: Jason Millman – UCLA
Image: The image is in the public domain.
Preliminary study: Open Access.
“Sleep function: An evolutionary perspective” by Jerome Siegel et al. Lancet Neurology
Sleep function: An evolutionary perspective
Epidemiological studies in industrialized societies indicate that 7 hours of sleep per night is optimal for people aged 18 and over, with higher and lower sleep rates predicting shorter lifespans. People living a hunter-gatherer lifestyle (eg, tribal groups) sleep 6-8 hours per night, the longest period of sleep in the winter.
The prevalence of insomnia in hunter-gatherers is low (about 2%) compared to the prevalence of insomnia in industrial societies (around 10-30%). Insomnia studies are often confounded by effects of stress to gain insight into sleep functions.
Considering spontaneous diurnal sleep duration in mammalian species ranging from 2 h to 20 h provides important insights into sleep function independent of deprivation stress.
Sleep duration is not related to brain size or cognitive ability. Instead, sleep duration among animals is correlated with ecological niche and food requirements, suggesting a role for wake-sleep balance in food acquisition and energy conservation. During non-rapid eye movement (non-REM) sleep, brain temperature drops to the waking level and rises during REM sleep.
Homeotherm order Mean daily REM sleep duration is negatively correlated with mean body and brain temperature, REM sleep in oviparous (monotremes) mammals, moderate in marsupials, least in placental mammals, and least in birds. Size.
REM sleep may play a key role in regulating brain temperature and metabolism during sleep and facilitating wakefulness.