Try to drink coffee or any time of drink with caffeine in the afternoon because caffeine gives you energy and will keep you awake.
Try not to watch TV, read or anything else apart from sleep in your room because if you do it will keep you awake and focused.
Turn the TV and volume of music down.
Only use a lamplight so that it can make you tired.
Reduce brightness on all gadgets so that it can save power and make you sleepy.
Before sleeping take a shower or bath.