What’s the difference between REM (rapid eye movement) and NREM (non-rapid eye movement) sleep cycles?
McNamara: REM is an odd physiological state. The bulk of it occurs in the latter half of the night’s sleep, toward morning. The brain is hyper-activated, more activated than during the daytime. Yet the body is paralyzed. All the antigravity muscles aren’t working, so you can’t move, and the eyes dart back and forth as if watching some scene. There is sexual activation. The autonomic nervous system is going through what we call periodic storms, or discharges. It’s a strange biological conglomerate. Sexual activation? Every night when you go into REM, men get erections, and if you’re a female the clitoris gets engorged. We engage in pelvic thrusting movements. Every 90 minutes human beings go into this sexual activation. Great, now I’m going to be too self-conscious to fall asleep. Is there an evolutionary reason for this? There must be. The first thing that suggests itself is that it somehow increases reproductive fitness. For men who complain of impotence, one way to determine if it’s
