Anoni mentions to avoid sugar/caffeine, but sugar gets immediately stored in your body and doesn't actually make people active but actually lazy. Getting carbohydrates (such as most if not all sugars) in your body (this instantly is stored, energy to be used for later) makes most people sleepy.
After I eat a carbohydrate-based meal, I almost instantly fall asleep. Whereas if I eat a protein-based meal I don't fall asleep and can stay up for quite a while until the 'direct-energy' has been used up.
That, and there just seems to be a difference between people. Some people stay up from drinking coffee, others fall asleep from it, and then there are others who arent affected by it at all.
I'd suggest to an hour or so before heading to sleep, you lay in bed, don't look at your computer/laptop/phone. Read a book or something.
I don't know how much sleep you do get, but some people simply just need more sleep or less sleep than others.
Also, according to research, people who seem to require less sleep seem to live longer than people who sleep a lot longer (8 to 9 hours).
Sleep deprivation is not good, but if you are getting sleep, then... Well *shrugs* it is different from person to person. If you notice you're getting side-effects from getting too litte sleep, then I hope what I suggested helps (or what anyone else suggests)
If you're not experiencing side-effects, I wouldn't worry too much about it (unless you sleep like half an hour or something, that seems a bit extreme ^^; ).