It depends on what circumstances. Make sure first that you judging it right. If you can't control your eyes as being so sleepy then you need a good rest. If you can take a shower, make sure to take a cold shower, It will refresh your arteries & it'll help you. If not, then wash your face with cold water & make sure make behind your neck wet with it as well. Massaging would help. Your back (spine) There's so many little-tiny arteries on your back, Beside the muscle, blood contains there slower so it feel tired after some while (also when spine stays steady for a long period it will make it more tired) anyway.
When you massage your back, you'll spread the bloods better & will refresh the muscle so you'll feel more awake suddenly cause your body feeling fresh. Massaging the corner of your forehead, spreading your face's skin. Massaging shoulders & neck can make your body fresh to give you some strength to stay awake longer, Stay in wind. When the wind hits your face, you'll feel more fresh,So it'll help you.Your body has this habit that will forget the primary order temporary so you might feel not sleepy for the next several hours, but then you'll be tired heavier, that needs rest without any excuse.Also drink coffee.
But make sure not put yourself in such circumstances often, cause lack of sleep has different side effects and it's better you avoid them.
Good Luck.
