If a person falls asleep while talking, riding a bike, standing or while doing physical activities, it should not be taken casually. It is a sign of a severe sleep disorder.
Narcolepsy is a neurological condition where the brain's ability to control the sleep-wake cycle is disrupted. In such case the patient can fall into Rem sleep after falling asleep for 90 minutes.
Nolan's behavior indicates that he is suffering from Narcolepsy and must consult a sleep clinic.
