It's all part of a decade long study from the UL Firefighter Safety Research Institute.
The study found having a bedroom door closed at night will limit the spread of fire.
And local firefighters agreed.
Ellsworth Deputy Fire Chief Gary Saunders said closing doors, "will limit the vent path of where the fire is going to go."
He also said a closed door will cut down on carbon monoxide levels.
"It's amazing how much property can be saved just by simply closing a door," said Deputy Chief Saunders. " It's not the big, heavy wooden doors, although those work great and those are probably the best ones. But even the light interior doors will hold back a lot of heat and a lot of temperature."
Researchers say a closed door makes a 900 degree difference. In a fire, temperatures can reach 1,000 degrees Fahrenheit, but with the same door closed shut the inside of the room will stay at 100 degrees.
Researchers say that with more synthetic materials and furniture in homes today, people have less time than ever to get out of a burning home - about three minutes.
"When you go to bed at night, close off doors," said Deputy Chief Saunders. "When you go away, leave closed doors behind you."
He says in a fire, it's a good idea to close doors as you exit the burning building.
This can further limit the spread of the flames.