Rethinking sunlight: What the latest science says about UV and health – A conversation with medical researcher Uwe Riedmann and the case for a new public approach

Reflections on the report – Conversation with medical researcher Uwe Riedmann. 

Sunforlife.info: What motivated the creation of this expert review, and what role did you personally play in its development?

Uwe Riedmann: I came in quite late. The paper was inspired by the great research many of my coauthors previously published. Because of their work and efforts in communicating their findings to the general population, increasingly more people know and are drawn to the upsides of sunlight/UV exposure. In this context, the Sunshine Health Foundation invited many of the top sunlight and vitamin D experts to Washington to talk about their research. The second meeting was last May, and one of those experts was my Mentor, Stefan Pilz.
While there were plans on writing a conference report, organisation, writing, structuring and streamlining such a paper is a lot of work. So, I was asked whether I was interested in handling the creation of this report. This was an exciting opportunity for an early-career researcher like myself to collaborate with some of the most respected experts in the field.

Sunforlife.info: The report calls for a paradigm shift in the way UV exposure is understood and communicated. What was the most urgent reason for advocating this change?

Uwe Riedmann: I think the most obvious reason is the general public’s consensus on sunlight. It is seen as unhealthy. It just causes skin cancer and skin ageing. However, research consistently shows that most people actually get too little sunlight, not too much. This is especially striking given that sunlight is a readily accessible resource. In an era marked by rising rates of heart disease, diabetes, dementia, and an ageing population, such findings about the broader health benefits of sunlight are more relevant than ever.

Benefits beyond vitamin D

Sunforlife.info: The review outlines many benefits of UV exposure, including effects on nitric oxide, serotonin, circadian rhythm, and immune regulation. Which of these mechanisms do you believe deserves more attention in both science and public messaging?

Uwe Riedmann: I do think all of them deserve more attention. Right now, the two that seem to have the most potential upsides are nitric oxide and immune regulation, which we also mostly focused on in our review. As (among other things) a COVID researcher, I am especially interested in upcoming studies on the immune regulation front. When it comes to public messaging, I believe it’s more important to emphasize the broader health benefits of sunlight beyond just vitamin D, rather than focusing on specific biological pathways. Many people mistakenly assume that taking vitamin D supplements can fully replace sun exposure, but research shows that the benefits of sunlight go well beyond what supplements can offer. The effects of supplementation alone are often quite limited, or even non-existent.

Risk communication and public policy

Sunforlife.info: Current public health messaging often emphasises the dangers of UV exposure. What do you believe are the consequences of this one-sided communication, particularly in regions with limited sunlight?

Uwe Riedmann: The obvious answer here is that the stigmatisation of UV exposure has led to, and will continue to lead to a lower life expectancy and quality of life. That is the main finding in the current literature. This is especially true for regions far from the equator, particularly for individuals whose skin types did not evolve for low-UV environments. There’s also a secondary, often overlooked consequence: beliefs can be marketed. For instance, while an average person has little practical use for SPF 100 sunscreen, such products are still aggressively (and successfully!) promoted.

Sunforlife.info: How can health authorities and media strike a better balance between UV protection and UV benefit?

Uwe Riedmann: First and foremost, the main goal must be that the average person realizes that there is a balance. This is a long process. One important part is, that authorities don’t push further unjustified recommendations and bans associated with UV exposure practices and methods. Later there are many subjects that need to be addressed. Some are UV intensity, duration of exposure, skin type, sunscreen effectiveness and application. However, for such recommendations we actually need more and better studies. Right now, we can say that most people would benefit from more sunlight exposure, but the specifics are still largely unclear. At least it seems that media outlets are increasingly writing on positive effects of UV. I am hopeful that this alone will help to slowly but surely fix the misunderstanding around UV exposure.

Tanning devices and controlled UV exposure

Sunforlife.info: Do you personally see any value in the responsible use of UV devices during months with little sunlight?

Uwe Riedmann: I think there is quite a bit of potential there. I personally use sunbeds in an attempt to “supplement” UV exposure during winter months. Currently, there are still some unknown factors concerning optimal length and frequency of sunbed use and their dependency on skin type. However, a big positive factor is certainly that they are already widely available and relatively cheap to access.

Mental health, circadian rhythm, and well-being

Sunforlife.info: How important is morning light exposure in your opinion, especially in our increasingly indoor and screen-based lifestyles?

Uwe Riedmann: This is an extremely hard question. Especially since it is intertwined with many other problems, subjects and unknowns. Is the real problem that we spend too much time in front of screens and not enough in the sun, or maybe it’s more about how we use those screens? Unfortunately, no one can say for sure.

As someone with a Master’s in Psychology, I’m particularly interested in a lesser-discussed aspect of this topic: The individual psychological dimension. While most conversations focus on biological pathways or public health trends, we often overlook how these findings can translate into small, manageable actions that support both mental and physical health.

For example, we have solid evidence that spending time outdoors can reduce stress, improve mood, and enhance cognitive function. Whether it’s going for a walk, being in nature, or simply getting morning light. The fact that these same activities are also linked to measurable physiological benefits, like circadian regulation or cardiovascular health, adds another layer. Crucially, these are things people can do themselves, which helps build a sense of self-efficacy. Which is maybe the best characteristic to have when it comes to positive changes in behaviour (health-wise or other).

Moving forward

Sunforlifeinfo: What research questions or public initiatives would you personally like to see prioritised in the coming years?

Uwe Riedmann: Right now, I am mostly interested in a closer dissection of how yearly variations in UV affect health, as well as a more specific understanding of the physiological changes and health effects that UV-emitting devices may provide (e.g. sunbeds). I also think an increased understanding of yearly UV variation is almost a prerequisite for deep comprehension of how and when to use UV-emitting devices. So, in a way, the end goal of both these questions is the same.

Sunforlifeinfo: What is one message about sunlight you wish more people — including doctors — truly understood?

Uwe Riedmann: I believe just a general understanding that there are many benefits to UV exposure would already be great. Interestingly practitioners and researchers I talked to, dermatologists or others, have been very open and interested in the subject (Unfortunately, even dermatologists are often surprisingly unaware of the broader health implications). However, it is not yet the point at which young doctors learn about this in university, which is a pity. On the other hand, in personal conversations with non-doctors, people have been very slow to let go of their negative view of UV.

Interview by: Ania D., Sun For Life
Published with permission. Learn more about the report: Beneficial health effects of ultraviolet radiation.