is there a certain chemical that someone would pump through the air system at your home or work that could make you fall asleep without any warning? Not like carbon monoxide, but literally one minute ...
Nitrous oxide is another anesthetic, but not so quick. Fentanyl is quick, but not likely to be an accidental exposure.
It is not necessarily a chemical that causes sudden sleep. Does it happen both at work and at home? It could be epileptic seizures.
Double vision could be a brain problem. Has there been a head injury?