That's hard when your mind starts like a washing machine. I've had that during the day before and it seemed relentless. My mum gave me some Bach flower remedy, white chestnut. I didn't think it would do anything, but was amazed when my mind did settle down and I could think straight. So if it's the relentless thoughts that won't stop, could try that
Or try doing something to occupy your mind rather than worrying, reading or colouring in (adult colouring in is a form of mindfulness, and you can get all sorts of books - I even saw a star wars one the other day!)
And there's other tips in a sleep tips post xx