OK, I'm not done looking, but I believe I'm going to lose this. From what I have found so far, the portable propane heater deaths ALL attribute to other brands, and it looks like the Mr. Heater is actually a suggested altenate. OTOH, from Mr. Heater's website:
Mr. Heater FAQQuestion:Why can’t I go to sleep while using my Buddy Heaters?
Answer:Because the heater is a portable device that could be bumped or have something fall on it while it is running, you do not want to let it be used “unattended” this would include going to sleep, leaving the room it is in while on, or putting it in an unoccupied area. This is for safety reasons.