Surely there's been studies done on this

[severa]

Because I want to know why is it that when I wake up an hour before my alarm and I go "Oh! I don't have to be up for another hour! More sleep!"

Then I do go back to sleep, and when my alarm goes off an hour I feel more tired than I did an hour ago!

Shouldn't more sleep = less tired?

Or in going back to bed am I disrupting my sleep cycle and there's something to do with melatonin?