Can this be explained?

Last night I was kind of sleeping, kind of still aware of what was going on and I was either thinking or dreaming that I heard the carbon monoxide detector go off in my house, but then i second guessed myself and thought if it rly went off my parents wouldve woke up. seconds later i remember sitting straight up in bed choking, suffocating, felt my lungs close up, felt dizzy, exactly as if i was breathing in carbon monoxide. I thought oh my god this is real I wasnt dreaming so I hopped out of bed and screamed for my brother and mom and dad hoping that they were still alive. I was shaking and coughing and my mom then came out and i told her what i thought happened and she told me everything was ok. i got water went out for fresh air, came back in still convinced it really happened. I dont think I was sleeping completely but why did i think and feel like this really happened?