Sunlight: Good For the Eyes as well as the Brain

By April 29, 2015 December 7th, 2016 Exercise

Seeing the natural light of the sun helps the brain work better. No, not staring into the sun, but allowing the eyes to be exposed to natural outdoor light—contact lenses, eyeglasses, sunglasses and windows block the helpful sun rays.

Of course, the sun is important because it offers us vitamin D for free, and is the major source of this important nutrient that has powerful effects throughout the body. Vitamin D allows one to more effectively use calcium, improves the immune system, helps prevents cancer, and is important for brain function. Yet, millions of people have insufficient levels of vitamin D, and rickets—a once common condition of brittle bones in children caused by vitamin D deficiency that was very rare—has made a big comeback. Much of the information about vitamin D can be found in my books and articles.

In addition to the healthy affect on your skin, sunlight also provides another positive benefit. The human eye contains photosensitive cells in its retina, with connections directly to the pituitary gland in the brain. Stimulation of these important cells comes from sunlight, in particular, the blue unseen spectrum. A study by Dr.’s Turner and Mainster of the University of Kansas School of Medicine, published in the British Journal of Opthamology in 2008 states that, “these photoreceptors play a vital role in human physiology and health.” The effects are not only in the brain, but the whole body.

Photosensitive cells in the eye also directly affect the brain’s hypothalamus region, which controls our biological clock. This influences our circadian rhythm, not just important for jet lag but for normal sleep patterns, hormone regulation, increased reaction time, and behavior. Most cells in the body have an important cyclic pattern when working optimally, so potentially, just about any area of the body can falter without adequate sun stimulation. Turner and Mainster state that, “ensuing circadian disturbances can have significant physiological and psychological consequences.” This also includes “increasing risk of disease” as the authors state, and as numerous other studies show, including cancer, diabetes, and heart disease.

The hypothalamus also regulates the combined actions of the nervous and hormonal systems.

The brain’s pineal gland benefits directly from the sun stimulation. The pineal produces melatonin, an important hormone made during dark hours that protects our skin. In addition, melatonin is a powerful antioxidant for body-wide use, is important for proper sleep and intestinal function, and can help prevent depression. (Aspirin, however, reduces melatonin production.)

Among the specific affects of the eye’s photosensitive cells are helping you get out of bed each morning. The transition from sleep to waking up requires the effects of the body’s adrenal glands, influenced by the brain’s hypothalamus and pituitary. Exposure to morning sunlight also helps raise body temperature to normal (after a slight reduction during sleep), and numerous brain activities including increased alertness and better cognition—helping mood and vitality. These changes are often not experienced in many people until their morning coffee kicks in. Taking a peek outside at the dawn’s first sunlight is a habit worth implementing.

Aging reduces the ability to benefit from sun stimulation through the eyes, mostly due to eye-related disease development, especially problems such as glaucoma, and cataracts. Chronic inflammation and carbohydrate intolerance are two common problems associated with these and other eye illnesses.

Up to 70 percent of those 65 years and older have chronic sleep disturbances, with potentially any of the other health problems mentioned above. Turner and Mainster conclude that, “Light deficiency, whether due to improper timing, suboptimal spectrum or insufficient intensity, may contribute to medical conditions commonly assumed to be age-related inevitabilities.”

Inside lighting may provide some eye stimulation if your light bulbs are the full spectrum type. But it won’t take the place of a regular habit of getting morning sun into unshielded eyes. This routine is even more important with age.

The bottom line: The sun can help brain function, which can improve the nervous system, hormonal regulation, muscle function, immune health, and carries many other benefits.


  • […] bodies and minds also benefit greatly from a safe and healthy level of exposure to sunshine. Things such as vitamin D, certain brain functions and sleep-wake cycles are all connected to […]

  • Jacoby says:

    On the one hand we are told exposure is NOT good for eyes. On the other hand now you are saying it is! Very confusing! Not sure what to do…

  • David says:

    Hi, i misplaced my glasses (transition lenses that helped to control the amount of light rays entering my eyes and correct my shortsightedness) and since i’ve been experiencing inadequate sleep and abnormal sleep patterns. I don’t fall asleep easily and don’t sleep for long.

  • Lu Chang says:

    From information I read that by staring at sunlight before 11 AM in the morning for 20 minutes is bad for the eyes? Would it be better to stay in the sunlight in the morning by not staring at the sunlight directly without glasses?

  • Bryan C says:

    All due respect,,, absolutely brilliant theory,explains how we exist ,more importantly the only page even remotely close to as why we essentially are not blind by two,. Lol. Evolution is a😊 wonderful thing. Thank you for helping me with my curiosity.

  • Ben says:

    I wear contact lenses from when i leave the house to when i get home. Therefore my eyes arent getting any direct sunlight at all. Am i likely to pay for this later?

  • sanjay says:

    I have eye power -2.25. …. Will the sunlight reduce the eye power …….. Plzzz can u say me

  • Vic Sandall says:

    The long Shadow rule :-

    If you live in a latitude region where your shadow is longer than your height, such as Scotland, then you will not receive sufficient sunlight exposure certain times of the year.

  • glasseson says:

    The effect of getting run over by a car because of not wearing glasses would have severe consequences for your health.

    • What do cars have to do with Vitamin D?

      You can get the requisite amount of sunlight in the time it takes to read a book chapter in your backyard.

      No cars there (usually).

      • LuAnn says:

        This is what I do. I often go outdoors sit in direct sunlight and do a crossword puzzle. Spend a total of 20 minutes. Really do feel better, more energized. Great info!

  • Thomas Sanocki, PhD says:

    This means we (who wear glasses) should be outside with our glasses off. An easy experiment to try! It also means people without glasses should be healthier? A fairly easy experiment to do.

    • Thomas:

      People who wear glasses can be healthier or unhealthier than people who don’t for a formidable array of reasons. My guess is that if you do a univariate epidemiological study on the health of glasses-wearers as compared to non-glasses-wearers, I’d be surprised if you find any effect at all. What I would expect, however, is that if you produce the effects of not wearing glasses for a glass wearer (within-subjects comparison), you might see a difference if the effect is strong enough.

      However, I would expect the effect of not wearing glasses vs. wearing glasses to be much smaller than the effect of not getting enough sunlight (amount X) vs. getting enough sunlight (amount Y), on the same dependent variable. So, glasses-wearers may be healthier than non-glasses-wearers in a strictly subclinical sense, where you’d expect clear clinical implications only when wearing glasses (or not) stacks together with an array of correlated or uncorrelated variables. But even supposing that wearing glasses only has subclinical effects over not wearing them (i.e. it doesn’t make you measurably unhealthier), that wouldn’t mean that wearing glasses isn’t pressing down slightly on the “unhealthy” end of the scale.

    • Fridr a Scandinavianf says:

      Hi Thomas Sanocki
      I have a similar question. Does glass or the plastic in sunshades stop a part of the sunlight that is beneficial to the eyes?
      I wear clear glasses to stop UV from damaging my eyes. I guess I should take it off when I enjoy the early moring sun…

      Can I get this early morning light from sitting in my window or take breakfast on my balcony that is covered with glass.

      I know that one day I will be old,and chanses are high that I will not go outside every morning during the winter. At that part of the year the sun shows itself only around midday.

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