Is It Safe to Leave a Space Heater On Overnight? An Expert Explains the Risks

If you live in a home that doesn’t have enough heat to stay warm, you may use a space heater to supplement the warmth. These compact appliances can provide enough heat to warm a small area and help offset high heating costs. While space heaters are common in many households, they come with at least one safety concern: Never leave one on overnight. Using a space heater during the day is common, but running it while you sleep can put both you and your home at risk. To learn why experts advise against overnight use, we spoke to Paul Christofi, the chief business development officer at FC Fire Prevention. Ahead, we break down the biggest hazards and share steps you can take to reduce the risks if you have no choice but to keep a space heater on overnight.

Why Leaving a Space Heater Plugged In Overnight Is Risky

It may feel tempting to leave your space heater plugged in and running all night while you sleep, but Christofi says it’s not recommended. Leaving a space heater on overnight draws significant power, and if something goes wrong, you may not notice until you wake up.

Common nighttime hazards that Christofi has seen include the heater tipping over, bedding or clothing shifting too close to the unit, a damaged power cord, or an outlet overheating. Being asleep when any of these issues occur significantly increases the risk, Christofi says. When you’re awake, you’re more likely to notice these warning signs and take action before they cause harm.

The Electrical and Fire Hazards to Know

As fire safety consultants and responders, Christofi says the most common issues they see on site aren’t heater malfunctions, but the outlets behind them. “We’ve come across outlets that were heat-damaged or partially melted because the connection was loose or worn and the heater was being used regularly,” he says.

Overheated outlets, damaged cords—especially ones that run under rugs or furniture—overloaded circuits, and arcing at the plug pose the biggest electrical risks when space heaters stay plugged in overnight or for extended periods. Christofi says the team at FC Fire Prevention strongly advises against using extension cords or power strips with space heaters. “Even heavy-duty ones aren’t meant for that kind of continuous load,” he says. “A heater should always be plugged directly into a solid, tight wall outlet.”

If You Use a Space Heater Overnight, Do This

While experts do not recommend using a space heater overnight, some situations may require it for warmth. (But first, try other methods to keep your home warm, or safely use a heated blanket.) If you choose to use a space heater, Christofi recommends using a newer model with tip-over protection. Place the heater on a hard, flat surface at least 3 feet away from anything combustible, and never run the cord under a rug.

In addition to these precautions, make sure all smoke alarms throughout your home work properly.