Summer is officially here, which means more time spent outdoors and soaking up the sun. While all that fresh air and activity is great for your health, it’s important to remember that sun exposure has its limits — and too much of a good thing can cause lasting damage. From the backyard to the beach, here’s what you need to know to keep you and your family happy and healthy all summer long.

The Good: Sunlight is a mood booster.

Exposure to sunlight increases endorphin levels. These are hormones released by the brain and nervous system that relieve stress and pain, and generally make us feel happier. That’s one way the sun “cures” seasonal affective disorder: a mild form of depression that sets in during dark winters, and abates as the days get longer in spring and summer. (Kegel, 2009) (Praschak-Rieder, 2008). Sun worshippers, rejoice!

The Good: It may help you lose weight.

Aside from the fact that we tend to be more active in warmer, sunnier months, a recent studyfrom the University of Alberta Diabetes Institute found that fat cells shrink when exposed to blue light from the sun. At this wavelength, light causes lipid molecules in the cells to reduce in size. This may contribute to the typical weight gain people experience during winter months, when their sun exposure is limited.

The Good: It helps your body produce vitamin D.

Vitamin D is an essential nutrient that helps support your body’s skeletal and immune systems. It increases the body’s ability to absorb of calcium and phosphorous, which in turn strengthens our bones. Whether from the sun, supplements, or fortified foods, Vitamin D can affect more than a thousand different genes that govern virtually every tissue in the body. (Mead, 2008). Studies suggest that vitamin D may also lower your risk of developing chronic conditions, including diabetes, heart disease, and cancer. (John, 2004) (John, 2007).

The Bad: UV rays can cause serious, lasting damage to your skin..

Dry skin and premature aging are the least of your worries when it comes to overexposure to the sun. Cancer is the most serious risk associated with too much ultraviolet (UV) radiation, especially if you leave your skin unprotected.

There are three types of UV rays: UVA, UVB, and UVC.

UVA contains the energy our bodies need daily. These rays are less intense than UVB, but travel deeper into the skin and can still cause skin disease (Haywood, 2003).

UVB causes tanning, burning, and wrinkling of the skin. This is the type of radiation that sunscreen protects against, and even short-term exposure (as little as fifteen minutes) can cause sunburn and lasting damage to cellular DNA (Krutmann, 2012).

UVC is filtered out by the (thinning) ozone layer. High exposure will also cause sunburn and possibly cancer.

Your body’s natural defense against UV rays is melanin: the natural pigment in your skin that causes you to tan. Melanin increases with moderate exposure to the sun, absorbing UV radiation and dissipating its energy as heat to prevent cell damage. But it can only do so much.

The Bad: Too much sunlight can hurt your eyes and affect your vision.

As with skin damage, the effects of radiation on your eyes is cumulative. In the cells and tissues of the eye are molecules called chromophores, which absorb light from different wavelengths at different rates. Over time, too much UV light can result in damage your cornea, lens, and retina. It can also cause cataracts; photokeratitis, a painful condition arising from too much UV exposure; and pterygium, in which tissue grows over the cornea and impairs vision. (Glazer-Hockstein, 2006) (Neale, 2003) (Solomon, 2006

So just how much sun is good for you — and how much is dangerous?

That depends on a variety of factors, including where you live, the altitude, the weather and the time of day. Generally speaking, fifteen or twenty minutes a day of sunlight, without sunscreen, is good for you — especially in the morning or evening, when the angle of the sun is low in the middle latitudes.

But during peak hours when the sun’s rays are strongest, or whenever you’re facing prolonged exposure (like a trip to the beach) there are measures you can take to protect yourself.

  • Reach for a sunscreen lotion (not a spray) that’s at least SPF 30. Be sure to re-apply it every two hours, especially if you’re swimming or exercising.
  • Wear plastic, wrap-around sunglasses, which are the most effective at blocking UV rays from all angles.
  • If you wear contacts, look for brands that are designed to effectively absorb UVB rays.
  • Do not rely on cloud cover. Just because they block the sun, doesn’t mean they are blocking UV radiation.
  • Consider other physical barriers to shield you from direct sunlight, such as clothing, hats, and umbrellas.

Let common sense prevail…

There is no one-size-fits-all approach to sun exposure. Brief contact with the sun is all that’s needed to soak up the benefits; unfortunately, it’s also all that’s needed to inflict lasting damage. Using sunscreen doesn’t automatically imply protection from other damaging effects of UV radiation, including melanoma (Wolf, 1994). But in this case, an ounce of prevention is worth a pound of cure.

Don’t be a statistic. Heed our advice on protecting your eyes and skin, and you’ll have a safer, healthier, happier summer.