Anti-depressants will help you be able to unplug your brain at night. Meet with a psychiatrist that will prescribe you different meds until you figure out what works for you.
Other strategies: Start writing out your thoughts on paper (not computer) and dump out all of your thoughts. Maintain a list of all the things you need to do, so that you are not responsible for remembering anything. Don't look at a computer screen or tv screen for the hour before going to bed. Read write or draw something. Don't drink any caffeine or sugary foods. Stick to a consistent sleep schedule, don't let yourself stay up way late, be extremely consistent with your bedtime and wake time. Drink milk before bed (the Calcium helps relax your muscles.) If you do have trouble falling asleep, don't get out of bed, and don't sleep in the next day or take a nap the next day. Do all of these things, not just some. Good luck!