He may suffer from narcolepsy.
Narcolepsy is a condition that causes a person to fall asleep at unexpected times. While in deep sleep, a person may continue to do voluntary movements but are not aware of it. Upon awaking from sleep, the person is often confused and/or dizzy and has to take a few minutes to come back to their senses. Narcolepsy is often impacted by high levels of thinking, processing, stress, or emotion.
I hope this helps! :)
