Blue light may not disrupt your sleep after all, researchers say

Evan Walker
Evan Walker TheMediTary.Com |
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Researchers say the overall brightness of light plays a larger role in affecting a person’s circadian rhythms than its color. AleksandarNakic/Getty Images
  • Blue light from the sun is vital in regulating a person’s sleep-wake cycle.
  • New research suggests the overall brightness of light plays a larger role in affecting a person’s “internal clock” than its color.
  • The findings further our understanding on the effects of light on sleep quality and duration.
  • Previous studies have shown that blue light from devices can damage the eyes and negatively impact sleep.

Of the seven colors in the visible light spectrum, Health">blue light is the one most people know and talk about.

The majority of light coming from the sun is blue light, making it vital in helping to regulate a person’s sleep-wake cycle.

However, blue light is also the type of light emitted by computer screens, smartphones, tablets, and LED televisions.

Previous research shows that too much exposure to blue light from technology devices can potentially damage the eye’s retina, lead to digital eyestrain, and negatively affect sleep quality and duration.

Now, a new study by researchers at the University of Basel in Switzerland suggests the overall brightness of light plays a larger role in affecting a person’s “internal clock” than its color.

The study was recently published in the journal Nature Human Behaviour.

For this study, Dr. Blume and her team recruited 16 human participants who were exposed to a blueish light, a yellowish light, and a white control light for one hour before bedtime.

Researchers designed the lights in a way that they activated the color-sensitive cones in the retina in a controlled manner and the stimulation of the light-sensitive ganglion cells was the same in all three conditions. This allowed scientists a way to separate the light properties that might affect the sleep-wake cycle.

Dr. Blume said they decided to focus on blue and yellow light in this study as a study in 2019 on mice found that yellowish light had a stronger effect on the mice’s rest-activity cycle than blueish light.

“The most striking changes in brightness and light color (i.e., changes from orange to blueish or vice versa) occur around sunrise and sunset, marking the beginning and end of a day,” Dr. Blume noted.

“Thus, especially changes along the blue-yellow dimension may be relevant for the internal biological clock.”

After reviewing this study, Dr. Benjamin Bert, an ophthalmologist at MemorialCare Orange Coast Medical Center in Fountain Valley, CA, told MNT that this study was interesting as it tried to show that while light color may not make a difference to a person’s sleep-wake cycle, other aspects that could.

“They talked about low melanopic light, which still is trying to get rid of the short wavelength light, in order to allow for an easier time of going to sleep,” Dr. Bert continued.

“But I think what we’re really seeing is that it’s so multifactorial that trying to figure out one specific thing that could be contributing to these issues or these concerns needs a lot of research to flush it out.”

MNT also spoke with Dr. Alexander Solomon, a surgical neuro-ophthalmologist and strabismus surgeon at Pacific Neuroscience Institute at Providence Saint John’s Health Center in Santa Monica, CA, who said the modulation of a person’s internal circadian rhythm is rather complex.

“There is a master ‘clock’ set by melanopsin cells — which are still most sensitive to blue light — but other activities such as meal timing and exercise can feed back to that master clock as well,” Dr. Solomon added.

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