muscle spasm
"I was prescribed Tizanidine 4mg mainly as a sleep aid but I also suffer from muscle spasm.  I take one pill before bed time and in about half an hour I'm ready for bed.  The problem? I'm way awake in 2 hours and need to take another pill.  This goes on all night.  If I take two at a time I start hallucinating, have weird dreams and I feel my heart beating faster (tachycardia). I continue to take it because two hours of sleep is better than being awake for 36 hours.  I will, though, ask my doctor to let me try soma."