You should definately completely write off the day after doing it, however you really shouldnt feel bad more then a day after. Just go to sleep as soon as you feel you can and when you wake up after a nice long sleep you should feel good(maybe a little cranky).

And for grinding your teeth just make sure you have something to chew on so you dont wreck your teeth ie. a straw, stirstick etc. I used to cut off a little piece of straw chew on that and then put a piece of gum in my mouth the straw and gum got all mixed up and it felt/tasted awesome and everyone just thinks your chewing on gum!