https://www.nationalgeographic...08/science-of-sleep/

While We Sleep, Our Mind Goes on an Amazing Journey

Nearly every night of our lives, we undergo a startling metamorphosis.

Our brain profoundly alters its behavior and purpose, dimming our consciousness. For a while, we become almost entirely paralyzed.

We can’t even shiver. Our eyes, however, periodically dart about behind closed lids as if seeing, and the tiny muscles in our middle ear, even in silence, move as though hearing. We are sexually stimulated, men and women both, repeatedly. We sometimes believe we can fly. We approach the frontiers of death. We sleep.

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Thanks for sharing.

I feel like I never get to stages 3 and 4 or REM.

I've always had problems sleeping, I've had many, many, sleep studies. I go thru stages 1 & 2 normally then go almost directly to REM, skipping stages 3 & 4, then wake up and start all over again.