Question

it is easy not to sleep whole night but not to wake up early.why?​

Answer 1

Answer:

Good Night and Sweet dreams.

Answer 2

Answer:

Feeling better after less sleep – including after getting less Deep or REM sleep – could be the result of your body trying to compensate for sleep deprivation. When you're short on sleep, your body releases stress hormones the next day and evening. These hormones supply the sensation of alertness.