Dash 8-100
Flight Attendant Airline Total 17.8; Flight Attendant Number Of Acft Qualified On 1; Flight Attendant Total 17.8; Flight Attendant Type 100
Distraction
Flight Deck / Cabin / Aircraft Event Other / Unknown
General None Reported / Taken
Aircraft; Human Factors
When the young college age man was leaving the aircraft; he was looking down at his iPhone and he did not see the low clearance of the airstair doorway. He also looked very out of it from sleeping during the flight. He bumped his head pretty good and kind of fell backwards a bit from the impact.  He did not sustain any injury and he left the aircraft. Low clearance of the airstair door caused the issue; as well as his being distracted and tired.
DHC8-100 Flight Attendant describes another passenger head collision with the top of the door frame while deplaning.