You should not leave your heater running overnight while you sleep. Leaving a heater on overnight or unattended not only creates a potential safety risk, but it can also dry out your skin and nasal passages.Click to see full answer. Besides, is it safe to run an electric heater all night?Never leave a space heater running while you sleep. Although modern heaters have safety features built in, you should never leave a space heater running overnight. Whether your heater runs on gas or electricity, it houses an element that gets hot enough to start a fire, and that’s a good reason to turn it off at night. is it dangerous to sleep with a space heater on? Many people rely on alternate forms of heating, such as electric heaters, to cut down on their energy expenses and keep warm during a cold winter’s night. However, space heaters are generally regarded as unsafe for use while sleeping, so follow this advice carefully to stay comfortable and still wake up in the morning. Considering this, what heaters are safe to leave on overnight? In general, it’s not recommended that you use a space heater while sleeping. Even though you’re technically present, you’re not aware of what’s going on in the house or even in your own bedroom.How long is it safe to leave a space heater on?The heater should be at least 3 feet away from furniture, curtains, bed, and blanket. Make sure that the smoke alarm in your house is fully functioning. Don’t disconnect or deactivate it. Also, change its batteries in every 6 months.