The Physical and Mental Benefits of Sun Exposure
When the cold weather has gone away and summertime has approached for much of the world, the sun starts to shine brighter and the days get longer. Warm weather brings back the leaves, flowers, wildlife, and more outside activities. As the sun stays in our visible sky for longer hours, happiness and energy levels may increase in many individuals as a result. The sun is the original source of life and energy for our planet and provides warmth and light for our solar system. Many believe there to be a spiritual connection between the sun and humans/wildlife dating back to ancient human history. But for now, let’s focus on what has been backed by science.
The correlation between the sun and mental/physical health has circulated since the 1800s. The Healthy City guidelines from the WHO defines a healthy city as one that has greenspaces. These spaces are open, undeveloped land with natural vegetation. Often referred to as the ‘lungs’ of the city. Greenspaces present a multitude of health benefits. Firstly, exercising in an outdoor environment has a greater effect on physical and mental health than working out in an indoor gym. Secondly, the social interaction encountered in greenspaces improves overall wellbeing. Thirdly, sunlight exposure provides vitamin D which counteracts seasonal affective disorder and makes you happier. Lastly, and lesser known, is that greenspaces provide a space for exposure to bacteria, protozoa, and helminths that can be found in nature and are important for the development of the immune system.
The human circadian rhythm also shares a correlation with sunlight exposure. A study done on sleep efficiency was observed in individuals living in arctic and Antarctic regions versus individuals living in equatorial regions. It was discovered that decreased natural light exposure led to increased sleep inefficiency and disturbances. More increased sleep onset latency (SOL) was observed in college students living in Norway rather than the students living in Ghana. Similarly, workers in Sweden reported more SOL than workers in Brazil. In arctic, Antarctic, and subarctic regions increased insomnia symptoms, decreased sleep efficiency, increased SOL, delayed sleep timing, and decreased slow wave sleep were more prominent in the winter months than the summer months. This is due to these regions’ placements on the globe, making it so that nights can last from days to months during the winter time. More research has yet to be done on sleep disturbances on polar residents during the summer months but there have been reports of aforementioned symptoms persisting during the summer. All in all, sleep hygiene is hinged on the determining factor of sun exposure time. It was concluded that exposure to sunlight before 8 pm worked best for the human circadian rhythm and helps with efficient sleep.
The correlation between dietary intake and sunlight exposure was examined in a research study conducted on 948 Korean adults. An increase of cancer, diabetes, cardiovascular disease, and auto-immune diseases was linked to a decrease of sun exposure. “There is a growing interest in the health burden caused by insufficient sunlight exposure rather than the risk of excessive sunlight exposure. Stress and other negative emotions such as depression and anxiety can also affect people’s eating behaviors and harm their physical and mental health” (Hwang, 2022). Not only was dietary intake observed, but self-rated health status and psychosocial stress was evaluated as well. Psychosocial stress and self-reported health status was evaluated using questionnaires where scores are evaluated on a number scale. Physical activity was evaluated through three categories on a daily basis: vigorous activity, moderate activity, and walking activity. In the group where subjects were exposed to 1 hour of sunlight daily they experienced higher levels of stress, they had a lower self-reported health status, and they did not engage in outdoor activities during the week. Nutritional habits in the sun deprived subjects took a hit as well. “Regarding eating habits, those with less than an hour of [daily] exposure to sunlight frequently ate fried foods, fatty foods, added salt, and snacks, and had significantly lower total dietary scores or three regular meals” (Hwang, 2022). It was found that the group exposed to the least amount of sun exposure had significantly higher stress scores than the other two groups that were exposed to sun longer on a daily basis. With the extensive research done on the effects on eating habits and stress and anxiety the link between sun exposure and diet is only further supported with such evidence. The test group that was exposed to the sun for three or more hours had more reported physical activity than their less exposed counterparts.
What is even more interesting is that the lack of sun exposure accounts for higher disease and disability rate than the overexposure of sunlight according to disease in disability-adjusted life years (DALYs) and the world health organization (WHO). According to Benefits of Sunlight: A Bright Spot in Human Health the consequences of excessive sun exposure are usually benign except for the malignant melanoma that usually occurs in the elderly. However, this is due to the long time frame between initial exposure and the manifestation of the cancer. Out of the three forms of skin cancer, melanoma is the most serious and can be life threatening if it spreads beneath the skin. The protective actions you take when you are young really will prove their effectiveness when you are older. The main benefit of sun exposure would of course be the production of vitamin D in the skin. It is a photosynthetic reaction triggered by the exposure to UVB. The efficiency of this process may be affected by body fat, clothing, sunscreen, and melanin. Levels of vitamin D and distance from the equator may account for increased risk of multiple sclerosis (MS) but more research needs to be done for a solid conclusion. However, studies have been done on UVB exposure and vitamin D levels and their effect on prevention of metabolic disorders. Sunlight exposure has proven to reduce the risk of developing type 2 diabetes, metabolic syndrome, and hypertension.
It is important to stay active and get outside when you can. Put the screens away; lace up and get outside! Whether you are going for a jog or walking to your local ice cream shop, getting in your daily dose of sun rays will boost your dopamine and lower your stress levels. Your mind and body will thank you. Just don’t forget to use sunscreen!
Sources:
Twohig-Bennett C, Jones A. The health benefits of the great outdoors: A systematic review and meta-analysis of greenspace exposure and health outcomes. Environ Res. 2018 Oct;166:628-637. doi: 10.1016/j.envres.2018.06.030. Epub 2018 Jul 5. PMID: 29982151; PMCID: PMC6562165.
Lubas MM, Maduro RS, Szklo-Coxe M. An exploratory study examining the associations between sunlight exposure, sleep behaviours and sleep outcomes during an Arctic summer. Int J Circumpolar Health. 2019 Dec;78(1):1574698. doi: 10.1080/22423982.2019.1574698. PMID: 30915921; PMCID: PMC7595109.
Hwang HJ, Choi YJ, Hong D. The Association between Self-Rated Health Status, Psychosocial Stress, Eating Behaviors, and Food Intake According to the Level of Sunlight Exposure in Korean Adults. Int J Environ Res Public Health. 2022 Dec 24;20(1):262. doi: 10.3390/ijerph20010262. PMID: 36612583; PMCID: PMC9819439.
Mead MN. Benefits of sunlight: a bright spot for human health. Environ Health Perspect. 2008 Apr;116(4):A160-7. doi: 10.1289/ehp.116-a160. Erratum in: Environ Health Perspect. 2008 May;116(5):A197. PMID: 18414615; PMCID: PMC2290997.
