Are you in both good mental and physical health?
Do you fulfill your daily requirements for minerals and vitamins?
There are strong connections that being in good health has many positive effects on the human sleep cycle, the most prominent being that if in good health you require less sleep. However being in a state of declining health in either physical or mental or both will have negative effects on the human body. One of the more prominent ways is you will begin to develop a inconsistent sleep pattern or generally start to require more sleep.
Alcohol in my guess is most likely not your problem, however you have to remember that Alcohol effects each person completely different than the next. The only common side effect people share is that the body treats Alcohol as a poison and thus creates the buzz or drunkenness when you go overboard on your consumption.
It also could be effects of the mental state you might be going through with school or god knows what. Is their anything predominantly negative on your mind or in your thoughts on a regular or daily basis?
The best advice I can give is 1.) see a doctor 2.) exercise regularly, eat healthy, and meditate or perform some action to clear your mind before going to sleep and you should have no problem fixing your sleeping patterns.