According to online resources the muscle cramps can be caused by various factors like medications. They can be evident in people who are withdrawing from medication and substances that have sedative side effects. This can either be anti-anxiety agents and alcohol or other sedatives as well. The cramps do disappear on their own over time but you should see a doctor if they are severe. You can get more information on this at, http://www.mayoclinic.com/health/muscle-cramp/DS00311/DSECTION=symptoms.