On the nature of beds and duvets

Why is it that at 1am, my bed is uncomfortable, my duvet too hot and my pillow not squishy enough, when at 6.35am (2 seconds after my alarm has rung) the aforementioned bed is heavenly, the duvet cosy and the pillow snuggly?

Is it a cruel joke by the gods? Or is it something inherent in the bed/duvet/pillow that actively prevents comfort and sleep, and then evily tempts you to stay in bed when you really really need to get up...

Bring on the weekend lie-ins.