Body temperature is not well regulated during REM sleep, and thus organisms become more sensitive to temperatures outside their thermoneutral zone. Cats and other small furry mammals will shiver and breathe faster to regulate temperature during NREMS—but not during REMS. With the loss of muscle tone, animals lose the ability to regulate temperature through body movement. (However, even cats with pontine lesions preventing muscle atonia during REM did not regulate their temperature by shivering.) Neurons that typically activate in response to cold temperatures—triggers for neural thermoregulation—simply do not fire during REM sleep, as they do in NREM sleep and waking.
Body temperature is not well regulated during REM sleep, and thus organisms. become more sensitive to temperatures outside their thermoneutral zone. Cats and other small furry mammals will shiver and breathe faster to regulate temperature during NREMS—but not during REMS. With the loss of muscle tone, animals lose the ability to regulate temperature through body movement. (However, even cats with pontine lesions preventing muscle atonia during REM did not regulate their temperature by shivering) Neurons that typically activate in response to cold temperatures—triggers for neural thermoregulation—simply do not fire during REM sleep, as they do in NREM sleep and waking.