When we first fall asleep, our heart starts to beat more slowly. Our breathing slows down and if something wakes us, we might not think that we had been asleep. And this is what they call ‘sleep dozing’.
If we are not awakened in the stage 1, we drift into a deeper sleep. Our pulse and breathing become even slower than they were during the sleep dozing. But you can still be awakened quite easily at this stage.
If we sleep longer than about twenty minutes, we go into this stage of sleep. Our body is now more relaxed and it would take a loud noise to wakes us up.
This is the deepest kind of sleep. You have probably heard of people who walk in their sleep. No one knows what makes people sleepwalk but a person can sleepwalk only during this stage of sleep. If someone wakes us up during this stage, we might feel very confused. And it might take us a few minutes to get used to being awake.
After about 10 minutes of Stage 4 sleep, we go back to Stage 3 and then to Stage 2, and then something quite different begin to happen. Our heartbeat becomes rapid. Our eyelids flutter and our eyes move. This stage of sleep is called Rapid Eye Movement or simply REM. Most dreams happen during REM sleep.
More questions about sleep begin to surface and scientists are still conducting researches and experiments to satisfy them.
Amazing right? Yeah, I know.