Help you wake up with a refreshing. And calculate the optimal sleep time around the sleep of humans which will not wake up. Research has shown that people will have a cycle of sleep (deep sleep - sleep) which in each cycle or in each cycle lasts 90 minutes we sleep and wake up during deep sleep. I do not want to get upset even if we sleep for a long time.

If we wake up when we are sleeping. Our brain is awake. There is no such thing as a cycle of sleep. For those who want to get help to wake up. No need to set the alarm clock to 10 rounds before taking a bath try to calculate the time to sleep. May be easier to wake up.