muscle spasm
"If I take 4mg at bedtime it will allow me to sleep, however, I can't wake when I need to get up to pee!  If I take 2mg (a 4mg pill broken in half) I can get up without a problem and still sleep most of the night. I also have a pain pump 9.0Mgr of hydromorphone, oral hydromorphone, trazodone.  Even with these drugs on board at bedtime pain keeps me from sleep more than a few hours total each night...  With the addition of some tizanidine, I am able to get nearly a full nights sleep. This is the only time I take it."