Late June in the Rogue Valley is the perfect part of summer for getting outside. Have you wondered who’s right, your mother (“Go play outside!”) or your dermatologist (“Avoid the summer sun ”)? The truth is somewhere in between, although I’ll mostly go with Mom. There’s a lot to say about the sunlight, but let’s keep it simple.
On the up side, we gain real benefit from spending time outside this time of the year. Exposure to daytime sunlight improves our mood and our sleep and can help to raise our vitamin D levels, for a start.
The beneficial effect on mood and sleep are probably related. Cortisol, made by the adrenal glands in response to sunlight, is the “get up and take charge” hormone that can decline in winter months, even causing depression – seasonal affective disorder – in sensitive individuals. Our bodies are happiest when morning cortisol production is high and levels decline throughout the day. Spending some time outside in the bright blue of a cloudless sky can be helpful. As daylight fades over the late afternoon and evening, our cortisol levels decline and our night-time production of melatonin (by our brain’s pineal gland) enables us to get a good night’s sleep. Keeping the two hormones in a daily rhythm requires good daytime sunlight and avoidance of overly bright lights in the evening, particularly the lights that come from tablet and laptop computers. Sleeping well of course enhances our mood the following day.
Early morning is also a great time to get some sunlight on your skin to enhance vitamin D production. There are two factors that determine whether you will receive any benefit from sun on your skin.
- Any time your shadow is shorter than you are, the sunlight is bright enough to activate receptors in your skin and stimulate vitamin D production. Your long shadow in winter indicates that the sun rays are too weak, so you won’t get a sunburn and you won’t get any vitamin D.
- Your skin works slowly, there’s no way around it. The fat-soluble vitamin D takes a while to soak into your skin, so it’s best if you don’t soap your sun-exposed skin for at least 24 hours (OK, try for 12?) even though it can take up to 48 hours to completely absorb.
On the down side, the effects of too much sun can be hazardous, particularly when that exposure leads to sunburn. Sunburn definitely raises your risk for two kinds of skin cancers, basal cell and squamous cell carcinomas. (Melanoma is actually more complicated: office workers, for instance, have high melanoma rates.)
What about wrinkling? There is no question that sun can contribute to skin aging, but current thought is that adequate levels of vitamin K2 and dietary collagen (eat meat cooked on the bone) are more important for maintaining youthful skin than sun avoidance.
Is sunscreen the answer? I recommend physically covering or shading the skin as a first choice, and sunscreen as the last but sometimes necessary resort. It’s hard to play tennis with a sun umbrella! Sunscreens can be toxic to us so it’s important to find safe ones at the Environmental Working Group’s website (here's their guide for 2017), and even the safe ones can be hazardous to the ocean’s coral reefs, so keep it at the minimal effective dose.
Later in the summer, the bright sun on a hot day raises other challenges, but in this mild early summer weather, get outside and play!