I keep falling asleep while studying!!

Do you guys have any tips on staying awake?
i'm really, REALLY stressed now!
almost everytime,
I start studying I tend to fall asleep!!!
Now, again,
I can't seem to open a book to study without dozing off=.=.........
even I'm getting enough sleep these days.....

coffee??
I'm not really like the taste so much..........
*sigh=.=