The night before your wedding is not the time to throw a bachelor or bacheloette party. If you're having a rehearsal dinner I suggest that you start the evening early - maybe 6 or 7pm - so that it won't end too late and you can get as much sleep as you can the night before your wedding.
If you or your groom are planning on having your bridal party spend the night with you give them a heads up that there are to be no wild parties planned, no surprises.
Of course you're going to be exciting and you may have trouble going to sleep but don't start testing out sleep aids. Have a calm night -- watch a movie (nothing to suspenseful), have some decaf tea or a glass of wine and relax and try to go to bed early.
You don't want to wake up the morning of your wedding with a hangover or exhausted, and you definitely don't want to oversleep.
Just be safe, I'd set an alarm clock and if you're staying at a hotel, schedule a wake-up call.