ges. "About twenty percent of 3 to 12-year-olds have at least one episode of sleepwalking, usually lasting two to ten minutes; some 5 percent have repeated episodes" (Myers 212).
             As Stage 4 comes to a close, the patient begins the important rapid eye movement (REM) sleep. During REM sleep, genitals become aroused even when the dream's content is not sexual (212). Myers states that a typical 25-year-old man will have an erection lasting 30 to 45 minutes on an average throughout this particular time of sleep. As the night continues, this sleep cycle repeats itself about every 90 minutes; and the REM period progressively gets longer. REM sleep may even grow to an hour in length at the end of the night. By the morning, 20 to 25 percent (100 minutes) of an average night's sleep have been REM sleep (212). In fact, if we sleep between six to nine hours a night, we can expect to have anywhere from four to six REM periods. This translates to mean that we may be dreaming anywhere from one hour and a half to two hours a night (Koulack 40).
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