why is it that when we have too much sleep we still feel tired?

Question: why is it that when we have too much sleep we still feel tired?
- Keywords:
  body clock,
  fatigue,
  sleep,
  tired,
  tiredness
Asked by meganmoult to Audra, Fiona, Gavin, Justin on 21 Mar 2012.
- Justin Lawley answered on 21 Mar 2012:
  
  I am not totally sure but it might depend on what you do when you get up. Normally tiredness is dependant on how long you have been awake (sleep pressure) and a internal factor that controls a daily 24 hour cycle. one thing that effect this is exposure to blue light (as in the sky). if you get up late and stay indoors you may feel tired. It may also depend on the quality of sleep you are getting.

Question: why is it that when we have too much sleep we still feel tired?