When we eat, finally we feel full. I know which mechanism causes the sensation of being full. But when we sleep excessively we often still want more sleep. Why does this happen? Is there a mechanism underlying this?
Studies have proven somewhat the opposite of what you're asking
For example a study from 2004 - "The impact of extended sleep on daytime alertness, vigilance, and mood" found that,
And thus concluded
Whilst an older study from '73 -"Performance and Mood Following Variations in the Length and Timing of Sleep" found that,
The study does go on to state however,
This perhaps suggests that the question which should be asked should not be why does oversleeping makes us feel tired, but why does the disruption of normal sleeping patterns make us feel tired?