The classic song Everybody's Free told us to always wear sunscreen. I think that advice deserves a closer look. Sunlight plays several important roles in our health.
The sun is a magic fireball that brings light into our lives. Light is a major zeitgeber for our bodies, an environmental cue that entrains or synchronizes our biological rhythms.
This is crucial for our circadian rhythm and sleep. Morning daylight gives the body a useful cue; I try to get some outdoor light early in the day.
Many of us spend much of the day indoors and get little natural light. At the same time, advice to limit sun exposure can make it hard to find a sensible balance.
To me, this raises a question about via negativa and how to apply it. I prefer to start by adjusting how long I spend in the sun rather than rely only on sunscreen and the toxic chemicals it may contain.
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Humans evolved with regular exposure to daylight. Our ancestors were outside all day, getting lots of this free source of light and heat.
Sunlight can affect us in several ways:
- It's an important zeitgeber for our circadian rhythm.
- Our skin needs sunlight to produce vitamin D, which can also come from some foods.
- UV light can inactivate some viruses in controlled settings.
- It lowers blood pressure.
- Daylight can lift mood and may play a role in mental health.
I hear much less about these possible benefits than about the risks. I am skeptical when advice to avoid the sun is presented without nuance, especially when Big Pharma has commercial interests in skin products.
So you have to get enough sun for several reasons. I know this is a problem in lots of countries, as I am from the Netherlands myself. How can you do this? The fact that the sun is good for us doesn’t mean that you should expose yourself all day.
You need safe sun exposure. Our skin can be antifragile, in the sense that it can adapt to modest exposure (hormesis). The amount of exposure your skin tolerates may change gradually, but it is worth paying attention to how it responds.
But too much stress can be damaging. Therefore, you should aim for moderate sun exposure based on your personal situation. Sunburn is a good cue to go by; avoiding a burn is an important limit, though it is not the only consideration.
Sunburns should be avoided because they are associated with skin cancer. The amount of sun exposure can vary greatly according to time of day, season, latitude, clothing and skin color. That is why one fixed duration will not suit everyone. Furthermore, a diet including vegetable oils is associated with skin problems such as sunburn and wrinkles.
If you get little sunlight, you may want to ask a clinician whether a vitamin D supplement makes sense for you.