 rapid eye movement (rem) sleep is a stage of sleep characterized by the rapid and random movement of the eyes. rapid eye movement sleep is classified into two categories: tonic and phasic. it was identified and defined by nathaniel kleitman and his student eugene aserinsky in 1953. criteria for rem sleep includes rapid eye movement, low muscle tone and a rapid, low-voltage eeg; these features are easily discernible in a polysomnogram, the sleep study typically done for patients with suspected sleep disorders. rem sleep typically occupies 20â25% of total sleep, about 90â120 minutes of a night's sleep. the first rem sleep period occurs 90-120 min after sleep onset with the last rem period usually being the longest and normally occurs close to morning. during a night of sleep, one usually experiences about four or five periods of rem sleep; they are quite short at the beginning of the night and longer toward the end. many animals and some people tend to wake, or experience a period of very light sleep, for a short time immediately after a bout of rem. the relative amount of rem sleep varies considerably with age. a newborn baby spends more than 80% of total sleep time in rem. during rem, the activity of the brain's neurons is quite similar to that during waking hours; for this reason, the rem-sleep stage may be called paradoxical sleep.{{cite book |last=myers |first=david |authorlink=david myers (academic) |title=psychology |edition=7th |year=2004 |publisher=worth publishers |location=new york |isbn=0-7167-8595-1 |page=268 |url=http://books.google.com/?id=oyubwpdsqzoc&lpg=pp1&dq=0716785951&pg=pa268 |accessda
Dream Neurophysiology Sleep_physiology