IT’S TIME TO ADD “CLOSE YOUR DOOR” TO YOUR FIRE SAFETY CHECKLIST 
Closing bedroom doors during a fire can help slow the spread of flames, smoke, and heat. It creates a barrier that may provide extra time for occupants to escape and reduces the risk of fire reaching the enclosed space. Closed doors can also improve conditions for firefighters when they arrive.
Most people who sleep with the door open do so because they mistakenly believe it’s safer – but that’s exactly the opposite of what the fire department recommends.
Start making a habit of closing not only your bedroom door at night, but your children’s bedroom door as well. This is also a good time to test smoke and carbon monoxide detectors, check your home for fire hazards and review your family’s escape plan, or create one if you haven’t already done so. These small precautions can make a big difference.
How your door locks work
The difference between how a room with an open door and a room with a closed door survives a fire is dramatic.
Smoke moves up and out and fills a room from the top down.
It therefore reaches the floor last, which means it cannot easily get under the door. This is why we are taught to stay on the floor in case of a fire.
Fire needs oxygen, fuel and heat to survive.
So if a fire can be compartmentalized, its spread will be slowed because it lacks oxygen. If the oxygen supply is completely cut off, the fire may even die out.
The more you can control the oxygen, the more you can control the fire.
If you close your bedroom door at night and a fire breaks out in the kitchen while you’re sleeping, you may have time to wake up and figure it out. That might give you just enough time to leave the building, or to call 911. But it could also give you a safe place to wait for the firefighters while the smoke, heat and toxic fumes are right outside your door.
You should actually close as many doors as possible in your home at night.