This was one of my biggest problem back then.. if the class starts to get boring, i just can help to fall asleep.. what i do is i usually drink water coz is lowers the levels of lactic acid in your system which may be causing you some drowsiness.. i also try to eat some sweets such as candies to add some sugar.. if i really can not help it, i will go to the washroom and splash some cold water in my fa