Sunlight: More than a mechanism for sunburn
DISCLAIMER
The content provided in this Substack post is for entertainment and informational purposes only and is not intended to serve as medical advice. The views and opinions expressed herein are those of the writer and should not be taken as definitive or authoritative. Readers should not rely solely on the information provided in this post to make decisions about patient care. Instead, use this content as a starting point for further research and consult a qualified healthcare professional before making any changes to treatment or medication regimens.
Introduction
Often when we hear about sunlight, the conversation is framed around its risks, such as skin cancer and eye damage. While these are indeed important considerations, they don't tell the whole story about sunlight's role in our lives. One crucial aspect of sunlight that deserves more attention is its capacity to produce vitamin D in our bodies and the ensuing impacts on mental health. In this post, we'll delve into the lesser-discussed benefits of sunlight, their influence on psychiatric illness & how it is different from oral vitamin d supplementation.
Sunlight: A Positive Influence on Health and Well-being
As a permanent fixture of life on Earth, sunlight is deeply woven into our physiological functions, influencing an array of processes that extend far beyond its fundamental role in photosynthesis. Its transformative touch on human health manifests in several ways that underscore its importance for overall well-being, mental health included.
Vitamin D Synthesis
Sunlight, particularly its ultraviolet B (UVB) radiation, is the catalyst for a remarkable biological process in our skin that leads to the production of vitamin D, often referred to as the "sunshine vitamin". This synthesis is a multi-step journey that starts with a compound in our skin known as 7-dehydrocholesterol. Upon absorbing UVB radiation, this molecule is converted into previtamin D3, which then undergoes a thermally-induced transformation to form vitamin D3, or cholecalciferol.
Subsequently, cholecalciferol is metabolized in the liver into 25-hydroxyvitamin D, and finally, the kidneys convert it into the biologically active form, 1,25-dihydroxyvitamin D or calcitriol. This final product is a potent hormone that orchestrates calcium and phosphate metabolism, essential for bone health. It also wields influence over immune function, modulating the immune response and playing a protective role against infectious diseases.
Importantly, the evidence linking vitamin D to mental health has been accumulating. Research suggests that vitamin D might protect against mental health disorders by influencing neurotransmitters, neuroplasticity, and inflammatory processes. The implications of vitamin D deficiency on mental health are an ongoing topic of exploration, with potential connections to depression, schizophrenia, and cognitive decline.
Sunlight Modulates Serotonin
The benefits of sunlight are not restricted to vitamin D synthesis. Exposure to sunlight plays a critical role in serotonin production, a neurotransmitter that contributes significantly to feelings of well-being and happiness. Serotonin serves multiple functions across the body, but it's perhaps most known for its role in the brain, where it helps regulate mood, social behavior, appetite, sleep, and even memory and learning.
The link between sunlight and serotonin levels has been widely researched. Light exposure during the daytime triggers serotonin release, while darkness prompts the production of melatonin, a hormone that helps regulate sleep. Reduced exposure to sunlight, particularly during the short, dark days of winter, can lead to lower serotonin levels, a factor implicated in seasonal affective disorder (SAD) - a form of depression that follows a seasonal pattern.
Circadian Rhythms: Sunlight's Role in Biological Timing
Sunlight also acts as the primary zeitgeber (a cue that influences the timing of biological rhythms) for our circadian rhythms. These internal "clocks" regulate numerous physiological processes, including sleep-wake cycles, feeding behavior, hormone secretion, and metabolism. Exposure to natural light during the day helps keep our circadian rhythms entrained to a 24-hour cycle, aligning our internal processes with the external environment.
Maintaining a synchronized circadian rhythm is critical for our health. Disruptions in this rhythm, such as those caused by shift work, jet lag, or even prolonged artificial light exposure, have been associated with various health issues. These include sleep disorders, metabolic syndrome, cardiovascular disease, and certain types of cancer. More recently, the impact of circadian disruptions on mental health has gained attention, with evidence suggesting a link to mood disorders like depression and bipolar disorder.
To sum up, sunlight, in its multifaceted role, contributes significantly to our mental health and overall well-being. Harnessing its benefits, while being mindful of the risks of overexposure, is a balancing act that holds promise for an improved quality of life.
Sunlight & Psychiatric Illness
With this general overview in place, lets move on to discussing specific ways that sunlight has been demonstrated to be related to psychiatric illness. It should be noted that sunlight's role in mental health, largely mediated through vitamin D synthesis, is a continually evolving domain of scientific inquiry. This relationship manifests across several areas, including depression,
Keep reading with a 7-day free trial
Subscribe to Short Bits for Inquisitive PMHNP's to keep reading this post and get 7 days of free access to the full post archives.