What legal drugs can be used to keep me awake when needed? sometimes i have to sleep little and go to work, thank you

Caffeine: I suspect caffeine (as in coffee) is your best bet here; however, the best option is to arrange things so you can get adequate sleep; lack of sleep is akin to being inebriated and you are likely to make serious errors of judgment;.

Help stay awake: Caffeine is legal and usually works well. Drink strong coffee as necessary. Avoid drugs.