How sunlight affects the brain and how much is needed for health

How sunlight affects the brain

Light hitting the retina affectsHow Does Sunlight Affect Our Mood? / BrainFact.org on the internal photosensitive ganglion cells that set the rhythms of sleep and wakefulness, affect cognitive functions and mood.

Since these cells are most receptive to blue light, such as daylight, scientists supposeHow Does Sunlight Affect Our Mood? / BrainFact.orgthat the sun can be of great importance for the emotional background and mental activity.

Increases the amount of serotonin

Serotonin is a substance that transmits signals between nerve cells and other tissues of the body, provides good mood and a calm but concentrated state.

This neurotransmitter is often referred to as the happiness hormone, and its deficiency is seen in depression.

In one study checkedG. W. Lambert, C. Reid, D. M. Kaye. Effect of sunlight and season on serotonin turnover in the brain / The Lancet indicators of hundreds of healthy people in different

seasons and found that the amount of serotonin in the brain was higher on sunny days.

This is especially important for people with depression. Just a few studies showed1. S. Leppamaki, T. Partonen, J. Hurme. Randomized trial of the efficacy of bright‑light exposure and aerobic exercise on depressive symptoms and serum lipids / Journal of Clinical Psychiatry
2. M. Brown, J. Goldstein-Shirley, J. Robinson. The effects of a multi‑modal intervention trial of light, exercise, and vitamins on women’s mood / Women & Healththat sun exposure reduces the symptoms of this disorder. Especially when combined with exercise.

Helps convert serotonin to melatonin

Serotonin is the precursor of another important hormone, melatonin, which answersA. Carrillo Vico, R. J. Reiter, P. J. Lardone. The modulatory role of melatonin on immune responsiveness / Current opinion in investigational drug for the quality of sleep and plays an important role in the fight against infections and inflammation.

Stay in bright sunlight in the morning hours helpsM. N. Mead. Benefits of Sunlight: A Bright Spot for Human Health / Environmental health perspectives the body starts producing melatonin faster at night and it is better to fall asleep.

By adjusting the rhythms of the “sleep hormone”, you can alleviate the symptoms of insomnia, premenstrual syndrome and seasonal affective disorder.

Improves blood supply

Several studies have confirmed that sunlight can affect blood flow in the brain. Such changes noticed1. FROM. Dani, G. Bertini, E. Martelli. Effects of phototherapy on cerebral haemodynamics in preterm infants: is fiber‑optic different from conventional phototherapy? / Developmental medicine and child neurology
2. E. Matt, R. G. Vasile, G. Sachs. Regional cerebral blood flow changes after light therapy in seasonal affective disorder / Nuclear medicine communications in infants after phototherapy, as well as in patients with seasonal affective disorder.

Activates the release of beta-endorphins

Class B ultraviolet waves (UVB) affect skin cells, keratinocytes and contributeS. K. Karin, U. Schallreuter A. J. Thody. Regulation of Human Epidermal Melanocyte Biology By β-Endorphin / Journal of Investigative Dermatology the release of beta-endorphins, natural opiates that dull pain and provide a sense of pleasure.

In addition, scientists have found that UV rays activateNguyen N. T. and FisherD. E. MITF and UV responses in skin: from pigmentation to addiction / Pigment cell & melanoma research the production of dopamine in the striatum, a brain structure that is part of the reward system and plays a role in the formation dependencies.

In one study, those who like to roast in the sun filledM. M. Warthan, T. Uchida, R. F. Wagner. UV Light Tanning as a Type of Substance‑Related Disorder / Archives of Dermatology questionnaires that are commonly used to identify alcoholism. And 53% of the participants showed signs of dependence on alcohol. In another experiment, 74 people out of 100 showedC. R. Harrington, T. C. Beswick, J. Leitenberger. Addictive‑like behaviors to ultraviolet light among frequent indoor tanners / Clinical and Experimental Dermatology abnormal addiction to sunburn.

Interestingly, the obsessive love of sunbathing is not unique to humans.

In one experimentG. L. Fell, K. C. Robinson, J. mao. Skin β-endorphin mediates addiction to ultraviolet light / Cell mice were irradiated with small doses of ultraviolet light - and they also found an increase in the level of beta-endorphins in the blood plasma.

Scientists supposeNguyen N. T. and FisherD. E. MITF and UV responses in skin: from pigmentation to addiction / Pigment cell & melanoma researchthat this mechanism is needed by mammals to force them to go out into the sun and thus avoid deficiency vitamin D.

Supports Cognitive Functions

Daytime sunlight has a wavelength of 470–480 nm, and it has the greatest effect on photosensitive ganglion cells: improves1. S. Gais, G. Vandewalle, M. Schabus. Wavelength‑dependent modulation of brain responses to a working memory task by daytime light exposure / Cerebral Cortex
2. G. Vandewalle, E. Balteau, C. Phillips. Daytime light exposure dynamically enhances brain responses / Current biology
3. W. D. S. Killgore A. Alkozei, J. R. Vanuk. Blue light exposure increases functional connectivity between dorsolateral prefrontal cortex and multiple cortical regions / Neuroreport working memory, vigilance and attention, helps to reduce distractions and not "get stuck" in thoughts.

This is especially pronounced in people with depression. One review study looked at data from 16,800 participants over 45 and found that frequent sun exposure protectsS. T. Kent, L. A. McClure, W. L. crosson. Effect of exposure sunlight on cognitive function among depressed and non-depressed participants: a REGARDS cross-sectional study / Environmental Health people with this disorder from cognitive decline.

Supports hippocampal health

One of the factors due to which sunlight can have a beneficial effect on memory, attention and mood - a sufficient amount of vitamin D. This substance is produced in the skin under the influence of UVB rays and affects the health of many systems and organs, including the brain.

In one experiment, they found that vitamin D-deficient mice learned significantly worse than their normal-fed counterparts.

Scientists, after checking the state of the brain of animals, establishedP. E. Mayne, T. H. J. Burne. Vitamin D in Synaptic Plasticity, Cognitive Function, and Neuropsychiatric Illness / Trendsin Neurosciencesthat due to a lack of a useful substance, their perineuronal network of the hippocampus (something like a scaffold that supports nerve cells) has decreased. The number and strength of connections between neurons in this structure also decreased. brain.

Scientists have decided that vitamin D deficiency makes the perineural network more sensitive to action enzymes, which leads to its destruction, harms the nerve cells of the hippocampus and affects memory and ability to learning.

Is it worth it to be in the sun as often as possible

Since daylight is good for mood and brain health, the conclusion is that you need to walk under the sun more often and go to the beach whenever possible.

However, do not forget that ultraviolet radiation is not the most useful thing. Overexposure to UVB rays can callR. Pandel, b. Poljsak, A. Godic. Skin Photoaging and the Role of Antioxidants in Its Prevention / ISRN dermatologyphotoaging - the appearance of deep wrinkles and age spots due to oxidative stress and loss of collagen protein. Moreover, mutations in damaged keratinocytes ableA. v. Lathema, S. Claerhout, M. Garmin. The sunburn cell: Regulation of death and survival of the keratinocyte / The International Journal of Biochemistry & Cell Biology lead to the development of skin cancer.

To avoid harmful effects, spring and summer adviseSun Damage: Protecting Yourself / Cleveland Clinic do not go out into the sun during a period of special activity of UV rays - from 10 a.m. to 4 p.m., and also use sunscreen with an SPF of at least 30, hide in the shade and wear clothing that covers most skin.

In theory, the less UVB rays exposed to the skin, the better for its condition.

At the same time, there is a risk of not getting enough vitamin D, which is necessary not only for good mood and vigor, but also for strong immunity, bones and overall health.

In order not to increase the risk of diseases and photoaging, it is worth adjusting the amount of sunbathing and taking into account the characteristics of your body.

How much sunlight will be enough

There are no clear prescriptions for the amount of sunlight needed for health and good mood.

Thus, in a study on the treatment of depression, significant improvements observedM. Brown, J. Goldstein-Shirley, J. Robinson. The effects of a multi‑modal intervention trial of light, exercise, and vitamins on women’s mood / Women & Health after daily 20-minute walks. About the same time needM. N. Mead. Benefits of Sunlight: A Bright Spot for Human Health / Environmental health perspectivesto get your daily dose of vitamin D - provided the sun is high, and the person does not use SPF cream and does not cover 40% of the skin with clothes.

It should be noted that not all people should do this. It is not safe to go out into direct sunlight without sunscreen:

• Owners of fair skin that burns quickly. In this case, the risk of skin cancer and photoaging is greatly increased.
• People with high sensitivity to sunlight. It may be innate quality or as a result of certain medications.
• People with a predisposition to skin cancer. To risk factors referSkin Cancer / Cleveland Clinic cases of similar diseases in relatives, many large moles, actinic keratosis, organ transplantation, reduced immunity due to diseases.

In these cases, you can get the required amount of vitamin D from food and supplements, and to maintain a good mood and mental abilities useY. Meesters, W. H. Winthorst, W. b. Duijzer. The effects of low‑intensity narrow‑band blue‑light treatment compared to bright white‑light treatment in sub‑syndromal seasonal affective disorder / BMC Psychiatry blue light bulbs.

The same advice is relevant for people living in regions where there is little sun.