Speaking of anabolic steroids it is a big question if they can make a problem to a diver. At least directly. Overdosing with anabolic is highly unlikely. If you drink a full bottle of pills or inject a double or triple dose nothing will happen. A cycle of testosterone, deca, winstrol, trenbolon etc. can give you hypertension, make you fat (if diet is bad) louse hair, fat skin, bad cholesterol levels which can led to cardio vascular problems in a long term, and some other sides, but will not make you lose consciousness. Not if there is not another health problem. If he took some other "chemical enhancement drugs" than anabolic steroids it can be. If he is a bodybuilder it can be he is also taking some other "things"...

Just my two cents

Regards
Mirko