not as far as I know. dissociation is thinking about other things then what is physically going on in the moment.

People with Dissociative Identity Disorder sometimes discribes their loss of time as they fell asleep because on minute they are thinking of ways to relax themselves to get away from whatever is physically happening and the next they become aware that physically time has passed and the one thing that everyone can relate to is going to bed at night and going to sleep, and waking up its a new day. so its easier to explain switching memory pieces (personalities) is like going to sleep.

Going to sleep literally when a person is overwhelmed is a symptom of depression and sometimes other disorders both physical and mental so you might want to see your medical doctor to rule out physical problems and also let your therapist (if you have one) know this is happening.