Sleep consists of 90-minute periods

The non-REM period is 70% of the total sleeping time, the REM is 30%. You reach the REM period within 60 minutes of falling asleep, then we return to it every 90 minutes and finally we spend 30 minutes in this phase right before natural awakening.

During normal sleeping time (7.5 hours a night) this period repeats itself five times. That is the reason why I recommend that you sleep for such a time that the number of hours spent are divisible by 1.5. So preferably 6, 7.5 or 9 hours. This way it is guaranteed you will wake up with your body ready to wake up!

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