The Sunny Science of Why We Need Sunlight

Written by Jacob Liu and Edited by Kevin Liu

From the greenest of plants to our enormous solar panels, humans use sunlight every day as a source of energy and life. However, we also need sunlight directly to maintain good health. While the general understanding is that too much ultraviolet radiation from sun exposure can lead to detrimental effects such as skin damage and even cancer, it still stands that humans need a certain degree of it. This basal necessity of sunlight primarily arises out of its ability to boost vitamin D levels in our bodies [1]. Additionally, humans need regular, consistent daily exposure to sunlight in order to regulate our own sleep cycles and other mental capacities [2]. Thus, as the summer months bring with them sunnier weather, we ought to appreciate sunlight’s benefits for our bodies.

Vitamin D is an important nutrient for human life, as it helps regulate the amount of calcium and phosphate in the body, which together promote healthy bones, teeth, and muscles. Lacking vitamin D can lead to various musculoskeletal problems such as bone deformities in children, including rickets or bone pain and weakness in adults, known as osteomalacia and osteoporosis, respectively [3]. Vitamin D is naturally present only in low concentrations in most foods, making exposure to sunlight and vitamin supplements the best ways to obtain vitamin D. While other essential vitamins are obtained from food, vitamin D is synthesized via a reaction in the skin that is triggered by exposure to ultraviolet B (UVB) radiation [1]. As infrequent exposure to sunlight leads to a greater risk of vitamin D deficiency, daily sunlight exposure is very necessary. Since sunlight availability varies geographically, a general trend of vitamin D deficiency follows, particularly in the winter months [3]. Consequently, it is recommended by public health institutions across the globe for people to ensure adequate daily sun exposure to avoid health issues and exacerbating any other conditions.

Sunlight also affects our sleep patterns; it has been discovered that direct and indirect sunlight exposure on the retinal cells of the eyes influences the secretion of the melatonin hormone when in darkness, which is essential for regulating the sleep-wake cycle [2]. It has been noted that brighter, consistent sunlight exposure leads to more melatonin production at night, thus resulting in a deeper and more restful sleep [4]. Additionally, exposure to sunlight is associated with increases in the brain’s release of the serotonin hormone, which results in a better mood as well as promoting calmness and focus [5]. Thus, adequate sunlight exposure at a sufficient brightness in consistent amounts supplements not only physical health but promotes mental and psychological health as well.

Given the positive aspects of physical and psychological health benefits associated with sunlight exposure, there must exist a balance to also account for the overexposure that leads to commonly known detrimental effects. As such, while we avoid these excessive damages from sun exposure, there still must be a minimal amount of sufficiently bright and consistent sunlight in specific minimal amounts to ensure adequate physical and psychological health.

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