muscle spasm
"I use Flexeril for muscle spasms that I have in my left arm and shoulder. One of the side effects of this medication is that it causes severe drowsiness. Once I take the medication, I must go to bed immediately.  I am able to sleep through the night where before the spasms would wake me throughout the night. When I first began to take the medication, I found that I was very tired when I awoke in the morning. To combat this, I go to bed about two hours earlier. This is appearing to work out well. Now I awake rested and free of tightness, aches, and pains."