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Can LED Light Strings Stay On All Night?

The quickest possible answer to this totally valid question is:


Barring defects, power failure, dead bulbs, or some world-ending event, most LED light strings you come across will remain lit, safe, and functional all night. The likelihood of those issues happening is slim. LED light strings have highly reliable build quality and are a resilient technology. 

You could leave them on 24 hours a day, every day and be fine for years, technically speaking.

How long do LED light strings last?

LED strings will generally last for 35,000 to 50,000 hours, or six years of continuous use, before they diminish to 70 percent of their original output. Blast them all night if you need. They’ll stand the test of time — at least, for a while.

How? They output far less heat and produce far more energy at a far lower cost than other types of lighting

“The LED bulb contains a number of different light emitting diodes, each of which produces light from a semiconductor chip with a negatively charged terminal and a positively charged terminal. As electrons move from negative to positive, they collide with positively charged particles (“holes”) and fall from a high energy level to a lower energy level. The drop releases energy in the form of light,” according to the Center for NanoScale Science at PennState.

They convert about 90 percent of the energy used into light.

“When an incandescent bulb is hooked up to a power supply, the electric current passes through a metal filament (usually tungsten), heating it until the filament is so hot that it glows. As the electrons move, they bump into the metal atoms of the filament. The energy of each collision vibrates the atoms and heats them up, eventually producing light. Only 10 percent of the energy used by an incandescent bulb is converted to light; the other 90 percent is lost as heat,” according to their study.

Incandescent bulbs, by the way, last about 750 to 2,000 hours. A drop in the bucket, comparatively speaking. 

All lightbulbs will produce light and heat from the collision of electrons. The amount of light-producing collisions as opposed to heat-producing collisions is the crux of light efficiency and longevity.

If there’s anything you walk away with from this section, it’s that LEDs are built to use energy better so that they last longer.

Is it safe to leave LED lights on?

To build on the concept in the last section, LED light strings emit very little heat. They’re safe to touch by hand, so if there’s a pet that likes to play with LEDs or a child that bumbles into them, as they tend to do from time to time, they won’t get hurt. They’re also less prone to fire.

This relates back to how heat is emitted from lights. 

The light emitted from bulbs is typically infrared radiation. This is what heats up the enclosures or glass around incandescent bulbs, making them hot to the touch. LEDs, however, generally do not emit IR radiation, therefore allowing them to be positioned in several areas throughout the home with little risk. 

“The energy consumed by a 100-watt GLS incandescent bulb produces around 12% heat, 83% IR, and only 5% visible light. In contrast, a typical LED might produce 15% visible light and 85% heat,” according to an article from LEDs Magazine. “Most significantly, the junction temperature affects the lifetime of the LED. Unlike other light sources, LEDs don’t tend to fail catastrophically (although a small number do, especially if you cook them); instead, the output of the LED decreases over time. Note that this also happens for other light sources.”

So, basically, don’t cook your lightbulbs. Got it. Moving on. 

It’s not just a matter of physical safety. LED lights contribute to financial security as well.

Compared to a traditional incandescent 60w bulb, one 12w LED bulb will save 75 percent of the cost, totaling $1 per year relative to an incandescent bulb’s $4.80 per year, based on 2 hour per day usage at 11 cents per kilowatt hour, according to the U.S. Department of Energy. Add that up across other bulbs left on all night and the energy savings per night are considerable.

The answer to this question is a resounding yes. You can leave LED light strings on all night and not worry about safety, cost, or reliability.