Untold Stories of the ER show; a sleep study specialist had attributed a person's ongoing repeated cardiac issues to his sleep apnea. The patient thought it was bunk but all the issues reportedly ceased once he started using the CPAP machine. The specialist, more specifically attributed his problems to his drop in blood oxygen levels during sleep.
EDIT: Episode was titled, "Harley Rides Again". (not that I understand how they came up with that title)