I used to have that, too. Either I grew out of it eventually, or I unintentionally trained myself out of it. Here's what worked for me (but note it might take a few months to really start showing an effect):

1) Find something (herbal supplement, chamomile tea, melatonin pills) that makes you a little sleepy and start taking it (or them) about 20 or so minutes before you want to go to sleep. Keep this up until a few months after you've begun to be able to fall asleep relatively quickly ( ... )