Our gas heater died the other day. The repair guy told us that it has been leaking carbon monixide. When I looked up chronic carbon monixide poisoning, many of the symptoms were very ADHD-like. Since I am an adult, and have a long history of syptoms, I think my dx of ADHD is correct. It is interesting that my symptoms became so much worse in September, when we started using the heat.
In any case, I would strongly suggest that those of you have have gas appliances have them checked, and have a carbon monoxide detector installed. Thank God that we couldn't afford to run the heater much, and that we shut it down at night. (You can see your breath in the morning. Typically, it's about 45 or 50 in here.) I don't know how badly it was leaking, but if we had run it like a "normal" family, at 68, instead of just off most of the time, it very well might have killed us.