Friends,
I am a guy aged 26 and I sleep about 5/6 hours a day. I eat breakfast at around 8:00 am and have lunch at 12:00 noon. My classes start right after noon and when I go to class I feel really sleepy. I barely pay attention to the proffesor and as a result i need to work hard at home. I tried drinking coke during the classes but it didn't help. Can somebody tell me how to get rid of this afternoon sleep? No red bull or monster suggestions. Thanking you in advance!
Grenade
P.S. Gosh, I typed "Fleeing" instead of "feeling", Proffesor instead of "Professor". These are all typos guys, I was not sleeping when I was posting this thread. LOL 

Try sleeping at night rather than a day, might help. 

First, sleep some more hours, at least 6-8 hours.

Second, do not eat heavy lunch three hours before your class starts. Means, if your class starts at 1 pm, do not eat anything heavy after 10 am. You can eat before 10 am if you want, but nothing after 10 am except some light snacks or drinks. Reason: When you eat food, blood from all parts of the body including the brain go to the stomach for digestion process. When there is no enough blood in the brain, you feel sleepy. 

Other than that, take coffee before class or in the class. 

 hey i do have similar problem.. and it's only if i am in class.. but if i go to movie or something else that is interesting to me... i never feel sleep.. is it the same with you grenade?
ani do you think are overweight.. i am little overweight and i think that is why i feel sleepy in the class?? i don't know if it's same with you..

Try to get at least 7-8 hours of sleep every night.
Sit in the front row where you're forced to pay attention to your professor.
Drink coffee!
And try to eat lunch after class if you're used to having heavy lunch (or just try to eat a light meal)!

 Bro, exercising is something that you might've overlooked by accident. Exercising isn't only healthy for your body, but for your mind too. Plus, it keeps you energized, providing you with energy. 

I thank you all for your valuable suggestions!!

Lunch ma bhat nakhau.

In addition to the above suggestions, also try these:
If you cannot arrange enought time to sleep during night, try taking nap of 20-30 mins during the day
Also drink enuff water.
 

I agree with default061...taking a nap is a good idea...but remember that taking a long nap (30+minutes) can actually make u feel lazy...I read this in an article which was based on a research finding...20 to 30 minutes is ideal

Do mild exercise early morning and take shower.., go to bed in time at evening (no facebook, youtube after 10 pm ;), ...  eat in time, never escape breakfast. It might be biological issue or result of depriviation of essential minerals in body. Try having quality multivitamins. Avoid energy drink, sugar or coffee.

Some people who snore (loud) during sleep  dont go through all 4 sleep-cycles during their night sleep, and actually they are sleep deprived. This might also be the reason.

Or if you are weak in study  of the particular subject, your mind tries to ignore it and you feel sleepy. ;)

Thank you all again. @ ans: I don't Facebook. Since I spent too much time I got bored and there was nothing useful but only family and friends network. So my favorite pastime is sajha these days and I am enjoying. Thank you so much for ur suggestions!!