As a world class worrier and habitual insomniac if someone says 'have a good night's sleep' or even worse 'relax' then it's a self-fulfilling prophecy that it's exactly what I won't
... so what I do instead is - initiate a 2 phase plan -
1. analyse what you need to do for whatever you're worried about,
2. do just that and then
and don't do any more revising or whatever's on your list.
4. Have a good filling dinner/supper that you like (if you're cooking for yourself pick one that's easy to make or better yet get a takeaway if that's possible).
Do this whether or not you think you'll chuck it up - it'll take your mind off the next day for a while still
Then you go into Phase 2
5. DO NOT GO TO THE PUB WITH FRIENDS or drink alcohol anywhere with or without company. Instead -
6. Do something gently physical that you enjoy - so a nice stroll to a place you like; walk the dog there if you have one; do yoga/pilates/tai chi or whatever; go for a swim if that's convenient; or, best of all have a nice long energetic cuddle with your favourite person if they're handy!
However... just do one
of the above or whatever gets you away from brooding or watching the telly for about 20 mins or longer.
7. If it's not time to go to bed - don't. But try to do something that's not going to get you too excited. Read an unexciting book or watch TV/DVD whatever - again something that's not going to get you too stimulated or go online to chat to someone who's pleasant and good company.
8. Drink something warm and comforting that's not
alcoholic or riddled with caffeine - absolutely no
coffee not even if it's de-caff!
9. Go to bed (if you're not already there with your favourite person, who I hope will have made and brought back 8 to you there). Make sure the room's not too hot or cold (17 deg Celsius is deemed about right) and, if it comforts you, that the bed linen is clean...
10. Follow your usual bedtime routine (although 'cuddling energetically' shouldn't be attempted again unless you really, really want to...
): Read; talk; listen to something soothing; meditate - doesn't matter so long as it's routine and won't wake you up too much. Then settle down to sleep around your normal time but before midnight
if you're a real night owl.
There's a phase 3 too...
If you really can't sleep then don't lie there worrying about it - get up and do something really boring that doesn't need too much thought - even things like ironing or light housework (not with a vacuum though!) - then go back to bed when you're feeling sleepy and try again. Best not to raid the fridge though...
Main thing is to go with the flow and try not to get too excited or experimental and to give your brain something to do aside from fret over and over about something that is going to happen anyway and that you have to get through. This works with other stuff as well as exams and although it doesn't always work, it will at least give you something alternative to do whilst you're worrying and divert your mind from it a little. And keep you from doing silly things like getting blind drunk or staying out too late with mates.