Rowan Jacobsen argues sunlight benefits are being lost in UK heat warnings

An aerial photo taken on 23 June shows Londoners packed along the edge of London Fields Lido, a familiar summer scene now routinely paired with warnings to cover up and stay in the shade. In a Guardian column, writer Rowan Jacobsen argues that the public message about sunlight has drifted so far toward avoidance that it no longer matches the balance of evidence on health outcomes.

Jacobsen points to a 2024 study that followed more than 88,000 UK Biobank volunteers using light-sensing wrist monitors to measure exposure to daylight and night-time light. According to the column, participants with the most daylight exposure were 34% less likely to die from any cause than those with below-average exposure; after adjusting for factors such as exercise and diet, the association still showed a 17% lower risk. The mechanism is not presented as a single vitamin-D story: Jacobsen says sunlight on skin produces vitamin D and “dozens of other beneficial molecules”, which the column links to lower blood pressure, reduced inflammation, improved sleep, and changes in mood and alertness.

That set of claims sits awkwardly beside the best-known risk: skin cancer. Jacobsen notes that higher sun exposure does raise skin-cancer risk, but argues that the trade-off is often discussed as if all skin cancers are equally lethal. The column cites roughly 3,500 UK deaths from skin cancer each year, and contrasts that with about 350,000 deaths from cancer and cardiovascular disease combined, framing skin-cancer deaths as about 1% of the larger total. The implication is not that sunlight is harmless, but that a public-health stance built around avoiding daylight can push people toward risks that are harder to see and less immediately attributable.

The behavioural shift the column describes is also institutional. Once a simple rule is taught for decades—sun is dangerous, shade is safety—reversing it requires officials to admit that earlier guidance was incomplete and that “optimal” exposure depends on skin type, latitude, season, and habits. That complexity does not travel well in slogans, and it creates liability anxiety: it is easier to warn everyone to avoid the sun than to defend personalised advice when someone gets burned. Jacobsen’s practical line is narrower: sunburns are harmful and linked to higher melanoma rates, but the bigger population-level danger may be getting almost no sunlight at all, a pattern the column says is increasingly common.

The article arrives amid a heatwave news cycle in which “heat” and “sun” are often treated as the same hazard. Jacobsen separates them: heat can be deadly, while daylight exposure—within limits—appears correlated with better overall health. The policy question left hanging is whether public messaging can distinguish between avoiding overheating and avoiding daylight without defaulting to the simplest instruction.

On 23 June, the camera over London Fields captured a city doing what it does when the weather turns. The column’s evidence suggests the risk is not only in the sunburns that show up the next day, but in the daylight people quietly stop getting at all.