I sleepwalk and stare into mirrors and begin rocking back and forth rapidly

It has come to my attention by my family members that i sleep walk and that i stare into our bathroom mirror and begin to rock back and forth rapidly. I have also done this while staring into corners. I don't turn on the lights which is strange because I am terrified of the dark. My mother has a history of sleepwalking as well but she stopped between the ages of 4 and 5 then she never had a problem with it again. Is this a medical condition?