My alters were going to therapy with me even before I knew they were there. It was my therapist that recognized that I have alters that made her suggest I get tested for mental disorders, and I came out of the testing diagnosed with having DID. The only thing I notice after switching is a headache. But I have noticed because my therapist has asked me to keep track of how I feel and tell her when I feel weird, that before switching I get a loud noise in my head and feel kind of like being on the upswing of a roller coster where everything looks far away and slow motioned.