which group experiences the highest level of rem sleep
Rapid eye movement sleep Although it manifests differently in different animals, REM sleep or something like it occurs in all land mammals as well as in birds. The primary criteria used to identify REM are the change in electrical activity, measured by EEG, and loss of muscle tone, interspersed with bouts of twitching in phasic REM.[85] The amount of REM sleep and cycling varies among animals; predators enjoy more REM sleep than prey.[17] Larger animals also tend to stay in REM for longer, possibly because higher thermal inertia of their brains and bodies allows them to tolerate longer suspension of thermoregulation.[86] The period (full cycle of REM and non-REM) lasts for about 90 minutes in humans, 22 minutes in cats, and 12 minutes in rats.[87] In utero, mammals spend more than half (50â€“80%) of a 24-hour day in REM sleep.[22]
Heart rate Many texts cite the normal resting adult human heart rate as ranging from 60–100 bpm.[1] Tachycardia is a fast heart rate, defined as above 100 bpm at rest.[2] Bradycardia is a slow heart rate, defined as below 60 bpm at rest. Several studies, as well as expert consensus indicates that the normal resting adult heart rate is probably closer to a range between 50 and 90 bpm.[3][4][5][6] During sleep a slow heartbeat with rates around 40–50 bpm is common and is considered normal. When the heart is not beating in a regular pattern, this is referred to as an arrhythmia. Abnormalities of heart rate sometimes indicate disease.[7]