muscle spasm
"Flexeril: short-term memory loss and extremely vivid dreams were my side effects. I had muscle spasms for a week and began taking 10mg only at bedtime. It made me sleep long but not well, as I had very strange vivid dreams that kept waking me. I also found myself incredibly forgetful, forgot things within an hour. I thought I was losing my mind. I stopped taking it immediately, but after a week it's still in my system.  "