Start a book or a movie and tell yourself that you won't fall asleep before you finish it.

It always works, I'm usually asleep within 15 minutes.

Give your body a nice work out for sixty to ninety minutes before you go to sleep and that would help. Don't forget to put your phone away from you, if switching it off seems to be a big deal. 

I don't know. Say umm shutting down your computer? lol

thank you Yannick ,Siva and Christina, i I had fallen asleep 10 minetes 。thank you very much!