Public health messaging about the sun tends to emphasize skin cancer risk, urging everybody to cover up and slather on sunscreen before going outdoors. But although it’s come to feel counterintuitive, research suggests small daily amounts of sun exposure confer an array of health benefits that outweigh the risks for most people, according to award-winning science and cultural writer Rowan Jacobsen. In an interview edited for clarity and length, Jacobsen digs into the findings from his new book, “In Defense of Sunlight: The Surprising Science of Sun Exposure,” 

For decades, we’ve demonized the sun. Turns out we were mostly wrong.

The following is an excerpt from Rowan Jacobsen’s forthcoming book, In Defense of Sunlight: The Surprising Science of Sun Exposure, out from Simon & Schuster June 16. It has been edited and condensed for Slate.

In the spring of 2025, I became intensely fascinated by a topic that, for the last seven years, had become increasingly present in my mind. That topic, which would soon consume my every waking thought and which I would eventually turn into a book, was sunlight.

The curiosity stemmed from an ongoing observational study of a single subject: me. I live in Vermont. Gorgeous summers, brutal winters. Over the years, I started to notice what a profound effect the different seasons had on me. Basically, winter sucked. This was not simple Seasonal Affective Disorder, a common condition in which people feel low during the winter months, and which is believed to be caused by a dearth of light entering the eyes. I didn’t feel depressed in winter. I felt as if my cells didn’t work.

After a long, cold winter and wet spring, there’s nothing like feeling the warmth of the sun on your skin. You probably know that too much sun can damage your skin and increase the risk of skin cancer. But is the sun good for you at all?

The short answer: Yes. “Sunlight is important for your health and mental well-being, but you also need to limit prolonged exposure because of the risks,” says Anna Radisic, M.D., an internal medicine physician at Hackensack Meridian Health in Lodi.

The key is finding a healthy balance. Here are five ways sunlight can boost your health, plus tips for enjoying it safely.

Summary:

Low vitamin D levels could be quietly making breast cancer surgery recovery far more painful. In a new study, patients deficient in vitamin D were three times more likely to experience moderate to severe pain after mastectomy surgery and ended up using significantly more opioid medication to cope. Researchers say vitamin D may help regulate how the body processes pain through its effects on inflammation and the immune system.

New research suggests vitamin D may support brain health and may be linked to dementia-related brain changes later in life.

A study published on April 1, 2026, in Neurology^® found that people who had higher vitamin D levels in midlife were more likely to have lower levels of tau protein in their brains years later. Tau is one of the key proteins linked to Alzheimer’s disease and other forms of dementia. When tau builds up abnormally in the brain, it can damage brain cells and interfere with memory and thinking.

The researchers followed nearly 800 adults who did not have dementia at the start of the study. Participants were about 39 years old on average when their blood vitamin D levels were first measured. More than a decade later, they had brain scans to look for signs of Alzheimer ’s-related proteins, including tau and amyloid beta.

Vitamin D deficiency is one of the most common nutritional deficiencies worldwide, yet it does not affect everyone equally. While seasonal changes, especially the winter months, play a major role in lowering vitamin D levels, there are several well-established factors that can significantly increase an individual’s risk of deficiency year-round.

Last week, we focused on the influence of the seasons on vitamin D levels, and how this time of year is when a majority of the population is at their highest risk of deficiency. Understanding the additional following risk factors for vitamin D deficiency is essential for both individuals and practitioners, as it helps identify who may need higher intake, closer monitoring, or more frequent testing year-round.