According to TMZ, Bob Saget didn't die from a heart attack or stroke. He actually died from a brain bleed, caused by hitting his head.
Authorities don't know what he hit his head on, possibly the headboard, with an obvious bruise on the back of his head.
It's believed, Saget didn't know the severity of the head injury and laid down to go sleep, never waking up.
There was also no evidence of narcotics or alcohol in his system.