muscle spasm
"I have very good luck with this as a pain reliever but the muscle relaxant part works a little too well. I mean a 500mg pill will knock me out for 18  hours. and 1000-1500 mg if the recommended daily dose. I have recently been taking 1/4 dose. (125mg) about 2 hours before bed and it still knocks me out for at least 12 hours. Then I wake up in the morning with hangover like symptoms, light and sound sensitivity, splitting headache, dry mouth. On the plus side at least I sleep."