Seasonal affective disorder (SAD) is a form of depression that affects many people as the days grow shorter and sunlight exposure decreases in the fall and winter months. However, recent research has uncovered a surprising correlation between sunlight exposure and suicide rates, with rates actually peaking in the springtime.
A groundbreaking study conducted by Shinsuke Tanaka, assistant professor in the College of Agriculture, Health and Natural Resources at the University of Connecticut, delved into the relationship between sunlight and suicide from a unique perspective. Published in the Journal of Health Economics, Tanaka’s research challenged the conventional wisdom by focusing on the seasonality of sunlight rather than just the total hours of daylight.
Using 25 years of meteorological data at the county level across the United States, Tanaka found a strong link between increased sunlight exposure and lower suicide rates. By analyzing NASA satellite data to measure solar radiation reaching Earth’s surface, Tanaka was able to pinpoint a direct correlation between sunny days and mental well-being.
Unlike previous studies that relied on daylight hours as a proxy for sunlight exposure, Tanaka’s research provided a more precise measure of solar energy reaching the surface. The results showed that a decrease in sunlight exposure by one standard deviation led to a 6.76% increase in suicide rates, highlighting the significant impact of sunlight on mental health.
Interestingly, Tanaka also observed a rise in Google searches related to depression and suicide during periods of reduced sunlight exposure, further underscoring the importance of sunlight for mental well-being. With suicide rates on the rise in the U.S., Tanaka’s findings shed light on the potential benefits of sunlight exposure in preventing mental health issues.
Moreover, Tanaka’s research has implications for the ongoing debate around solar geoengineering technologies, which aim to mitigate global warming by reducing sunlight reaching Earth’s surface. The study’s findings underscore the potential mental health costs of artificially reducing sunlight, emphasizing the need to consider the holistic impact of such interventions.
In conclusion, Tanaka’s study adds a new dimension to our understanding of the relationship between sunlight and mental health, highlighting the crucial role that sunlight exposure plays in preventing suicide. By acknowledging the mental health benefits of sunlight, we can prioritize strategies that promote healthy exposure to natural light for improved well-being.

