Morning exposure to deep red light improves declining eyesight

Saturday, December 18th, 2021

Just three minutes of exposure to deep red light once a week, when delivered in the morning, can significantly improve declining eyesight:

In summary, researchers found there was, on average, a 17% improvement in participants’ colour contrast vision when exposed to three minutes of 670 nanometre (long wavelength) deep red light in the morning and the effects of this single exposure lasted for at least a week. However, when the same test was conducted in the afternoon, no improvement was seen.


In humans around 40 years old, cells in the eye’s retina begin to age, and the pace of this ageing is caused, in part, when the cell’s mitochondria, whose role is to produce energy (known as ATP) and boost cell function, also start to decline.

Mitochondrial density is greatest in the retina’s photoreceptor cells, which have high energy demands. As a result, the retina ages faster than other organs, with a 70% ATP reduction over life, causing a significant decline in photoreceptor function as they lack the energy to perform their normal role.

In studying the effects of deep red light in humans, researchers built on their previous findings in mice, bumblebees and fruit flies, which all found significant improvements in the function of the retina’s photoreceptors when their eyes were exposed to 670 nanometre (long wavelength) deep red light.

“Mitochondria have specific sensitivities to long wavelength light influencing their performance: longer wavelengths spanning 650 to 900nm improve mitochondrial performance to increase energy production,” said Professor Jeffery.


  1. Slovenian Guest says:

    You should also use a red light in your bathroom after dark, or a flashlight with a red filter when walking around at night, because: “Rhodopsin is what allows the rods in our eyes to absorb photons and perceive light, making it essential to our vision in dim light. As rhodopsin absorbs a photon, it splits into a retinal and opsin molecule and slowly recombines back to into rhodopsin at a fixed rate. However, this is a gradual process, which is why it takes a while for our eyes to adjust in the dark. For humans, it takes about 45 minutes for our eyes to adjust to the dark.

    This is why it is important to stay away from bright lights once you have developed your night vision because this protein is extremely sensitive to bright lights. Once rhodopsin is exposed to bright light, it immediately photobleaches and breaks down — the rhodopsin splits back into retinal and opsin molecules. As a result, the rhodopsin that took so long to build up is no longer present in our eyes, and we are essentially blind in the darkness until that rhodopsin recombines back to its state.

    But over the years we have figured out ways to create light that is not so detrimental to our night vision. For example many lights now have a red light feature. Rhodopsin is not as sensitive to red light due to its long wavelengths — red light depletes the stored rhodopsin at a very slow rate. As a result we are able to preserve our night vision with red light rather than destroy it.” via

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