[throwawaynay]

not an expert, but isn't the sleepiness part the least of your problems in that situation?

[treeman79]

IQ drops a lot with Carbon monoxide.

Perfectly obvious stuff like “I’m being poisoned”, doesn’t occur to you.

[ksaj]

If its because of carbon monoxide building up in the room, it's a pretty big problem.

[NoPicklez]

I think that might be what the user is alluding to