If you wanna fall asleep, read a textbook or something boring. It will tire you out and make you bored and sleep. Works for me every time. I also sometimes "scare myself to sleep" by thinking that if I didn't fall asleep, I wouldn't be safe or something. If you have insomnia or something, try natural things like tea or lavender to help. If that doesn't, try asking someone who specializes in it. OTHER THAN THAT YOU CAN STAY UP ALL NIGHT PLAYING GAMES :D
Um, just try and tire yourself out, combined with not thinking bout sleeping. Also, don't worry about not being able to sleep for a while; it's no big deal, and can stop you from sleeping further.
Play games that take a long time to complete (rounds and stuff). Also try not to consume soft drink and chocolate before hand, even hours and hours before. I know watching long videos on youtube make me sleepy, so maybe watch some good eps of Game theory.