Why is it that the longer you sleep, the sleepier you feel ?!

Best Answer - Chosen by Voters

When you do something for long time your body get used to for that and demands more and more and when you dont provide then it will be upset i.e. "headache". Its not only with sleep its with everything in life.
Make a routine and follow that.
Bring everything in that routine not only sleep.
With little practice you'll be fine.

Wish you healthy body
Dr Rudra

http://www.rudraayurveda.com/

it has nothing to do with how long you sleep, but rather, which "phase" of sleep you are in when you wake. im not sure, but i think it is better to wake up in the middle of REM because that is when you dream, so your body is the most "awake." either that or i could be entirely wrong and that is the deepest part of sleep so you wake up tired. im not 100% sure. i am 100% sure that waking up in the right phase of sleep is most refreshing however. there are even "bio-alarm clocks" that can measure your brainwaves while you sleep and wake you up so you will wake up refreshed!

i have the sleep cycle app for iPhone (it measures your movement, not your brainwaves, so its not always perfect, but its better than a classic alarm clock! thats for sure!)

You've pretty much described my sleep pattern
The REM cycle is rather complicated, I would suggest you do further reading on it than what is really here. It isn't always about length of sleep either, your body is going to cycle based on many different factors- including previous sleep patterns. There are actually alarm clocks out now which track your REM pattern and wake you up at the best time so you don't go through the headache/sleep stuff...

The longer you sleep, the further into the sleep cycle you get so when you wake from it your brain has a harder time adjusting than if you were in an early stage of sleep.