I would lean towards Narcolepsy (falling asleep at random times). I am not a dr. though. See if he can get into a sleep specialist and get a sleep study done. This is important. If he is falling asleep at the wheel, a jerk awake while driving could cause a serious accident, and injure/kill somebody.
Narcolepsy is where someone is falling asleep all the time in all situations. My Sisters boyfriend suffers from it and has the same problem
it sounds like a sleep disorder
HE NEEDS TO GO TO A SLEEP LAB AND BE TESTED FOR NARCOLEPSY. I HAVE A SERIOUS CASE OF NARCOLEPSY AND HAVE HAD THE SAME SYMPTOMS SINCE ABOUT THE AGE OF 16. I AM NOW 53. WHEN I WAS YOUNGER, DR.'S WOULD TELL ME TO GET MORE SLEEP! THERE WERE NO SLEEP LABS AND SPECIALISTS IN SLEEP DISORDERS. I WAS 34 YRS. OLD WHEN I WAS NEARLY KILLED BY A TRAIN BECAUSE I FELL ASLEEP AT THE WHEEL WHILE DRIVING WITH MY 2 YR. OLD SON IN THE CAR. THE TRAIN STOP BAR CAME DOWN ON MY WINDSHIELD WHILE THE LIGHTS WERE FLASHING AND THE BELLS WERE RINGING. EVEN THE HORN OF THE TRAIN DIDN'T WAKE ME UNTIL THE TRAIN WAS PASSING AND IT LITERALLY MISSED KILLING US BY ABOUT 2 HAIRS!! SINCE I HAVE BEEN DIAGNOSED AND TREATED WITH MEDICATION, I HAVE A WHOLE NEW LEASE ON LIFE. PLEASE ASK HIM TO GET HELP AND BE THANKFUL THAT THEIR IS HELP OUT THERE THESE DAYS. IT WILL CHANGE HIS LIFE AND MAYBE SAVE IT SOMEDAY. GOOD LUCK!