Why Public Health Must Balance Heat Protection with the Benefits of Daylight

As extreme heatwaves become more frequent across the world, public health messaging has understandably focused on avoiding excessive sun exposure. However, emerging scientific evidence suggests that this approach may have become overly simplistic. While extreme heat remains a serious health hazard, growing research indicates that regular, moderate exposure to sunlight is essential for physical and mental well-being. The challenge for policymakers is no longer choosing between sunshine and shade—it is learning how to balance both.

For decades, public health campaigns have emphasized the dangers of ultraviolet (UV) radiation, linking excessive sun exposure to skin cancer and premature skin ageing. Those risks remain real, particularly during peak daytime hours and prolonged exposure without protection. Yet scientists increasingly argue that many people have interpreted these warnings as a reason to avoid sunlight almost entirely, inadvertently creating new health concerns.

Sunlight plays a fundamental role in regulating the human body’s biological clock, supporting healthy sleep cycles, mood regulation and hormone production. It is also the body’s primary natural source of vitamin D, which is essential for bone health, immune function and muscle strength. Research has also associated regular daylight exposure with lower risks of depression, cardiovascular disease and some metabolic disorders, although these relationships continue to be studied.

The timing of exposure is increasingly recognized as just as important as the duration. Morning and late-afternoon sunlight generally provide many physiological benefits while exposing people to lower levels of harmful UV radiation. In contrast, remaining outdoors during peak afternoon heat—particularly during heatwaves—substantially increases the risks of dehydration, heat exhaustion and heatstroke. Public health advice therefore needs greater nuance than simply urging people to “stay out of the sun.”

Climate change further complicates this balance. Rising global temperatures are making heatwaves longer, more frequent and more intense, increasing heat-related illness and mortality across many countries. Scientists estimate that thousands of excess deaths in Europe have already been linked to recent extreme heat events, highlighting the urgent need for improved heat preparedness and urban adaptation.

This changing climate also demands a shift in urban planning. Expanding tree cover, improving shaded public spaces, designing cooler buildings and creating more accessible parks can allow people to enjoy the health benefits of daylight while reducing exposure to dangerous temperatures. Such measures support both climate adaptation and preventive healthcare.

For individuals, the practical lesson is moderation rather than avoidance. Seeking sunlight during cooler parts of the day, wearing appropriate protection when UV levels are high, staying hydrated and limiting strenuous outdoor activity during peak heat can help maximize health benefits while minimizing risks. The objective is not to fear the sun but to respect its intensity.

Ultimately, the science suggests that the greatest health threat is not sunshine itself but extremes—whether prolonged ultraviolet exposure or complete avoidance of natural daylight. As the climate continues to warm, successful public health strategies will need to communicate this balance more effectively, promoting safe outdoor activity while strengthening protection against increasingly dangerous heatwaves.