why is it that people can sleep for a very long time during night but during day time they sleep for

Question: why is it that people can sleep for a very long time during night but during day time they sleep for a shot period of time?
- Keywords:
  day,
  night,
  people,
  sleep,
  time
Asked by absb266 to Charles on 17 Jan 2017.
- Charles Kamau answered on 17 Jan 2017:
  
  Hehe. Great observation. The body needs rest. They say 6-8 hours is just as fine. A majority of us tend to be so active during the day, hence rest during the night; sleep. However, we have people who also work at night and are very active – so they tend to rest, sleep, during the day. It’s just about the cycle the body is used to.

Question: why is it that people can sleep for a very long time during night but during day time they sleep for a shot period of time?