High summer has returned to the UK, and with it, the usual warnings about the dangers of sunlight and reminders to seek shade and cover up. After years of such advice, most members of the public naturally assume that the science connecting sun exposure to poor health is well established, so people are often shocked to learn that the opposite is true: those who spend more time in the sun tend to be healthier. A lot healthier.

I know because I began researching the subject nine years ago after stumbling upon some studies – and I’ve stayed on the case ever since, now summarising everything we know in my new book, In Defense of Sunlight. It contains good news for many people: we don’t have to fear the sun nearly as much as we thought. In fact, most of us could benefit from a bit more exposure.

We’ve always known that sunlight hitting skin produces vitamin D, but we now know that it actually produces dozens of different beneficial molecules. Those molecules lower blood pressure, reduce inflammation, increase energy and alertness, improve sleep, and make you feel better by releasing natural endorphins in the brain. The result? Less disease, better longevity.

Let’s run the numbers. In 2024, scientists published a study in which they attached light-sensing wrist monitors to more than 88,000 volunteers in the UK Biobank dataset and tracked their light exposure, day and night. Then they followed those volunteers for years to see how they........

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