Energy-Saving Lightbulbs Can Interfere With Sleep

Emily Willingham

October 05, 2021

When we can't sleep, there are many possible culprits and researchers are adding a new one that many haven't considered before: the LED lightbulbs we switch on after dark.

The human eye detects sunlight as white, but in reality, it contains the spectrum of colors, and different parts of this range dominate at different times of day. In daylight, cells at the back of our eyes detect bright sun, in which blue light dominates. In response, these cells signal the body to produce hormones and other chemicals that support being awake and alert. In the waning evening light with diminishing blue tones, the same cells set the rhythm of our night, preparing us for sleep.

Or they would, if we didn't flick our light switches on and saturate our space with blue light in the evenings.

The culprits are the light-emitting diode (LED) bulbs that many purchase because they use less energy and last longer than conventional bulbs. The tradeoff could involve our health and some studies point to associations between prolonged blue light exposure and everything from cataracts to insomnia and mood disorders.

Violet Bulbs

However, researchers at the University of Houston may have landed on a way for us to save energy and our eyesight and sleep.

They've developed an LED bulb equipped with a chip that emits light in the less health-disruptive violet range. Special materials in this chip absorb this violet light energy and convert it, leading the bulb to emit what looks like the soft glow of evening to human eyes. The human brain responds with signals that sleepy time is approaching.

The light from these violet LEDs still includes some emissions in the blue range, which doesn't need to be blocked entirely. Researchers hope that the violet LED version will lead to improved sleep, according to a short podcast from the National Science Foundation, which funded the work. But the chip materials that absorb the light energy still need some tweaking before they will be available to illuminate our lives.


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