You know that short-term exposure to sunlight is important for your overall health—especially those hits of the morning sun when the UV rays are lower. Sunlight also helps vitamin D production and is known to increase serotonin levels, which can help decrease depression and anxiety, and help improve sleep quality. But there are few other things to keep in mind when it comes to the sun.

So let’s talk about what an excessive amount of sun exposure can do to your cellular health, specifically in terms of UV damage and other stressors.

What is UV damage?

First, let’s take a look at how UV rays affect our cells. There are three types of UV rays: Ultraviolet A, B, and C, also known as UVA, UVB, and UVC.

The last two types, UVB and UVC, are mostly absorbed by the ozone layer, although UVB helps the body produce Vitamin D. That being said, the main ultraviolet radiation you’re exposed to here on earth comes from UVA. When you’re not properly protected by clothing or sunscreen, proteins and DNA are the primary targets for damage, which means your cells take the main hit and struggle to carry out their main functions, like energy production and repair. And if your cells can’t repair themselves, that’s where the aging process begins.

What is cellular stress?

Excessive amounts of sunlight exposure stresses out your cells by depleting your NAD+, an important coenzyme in cellular energy and repair. Let’s take a look at why.

• Your body uses NAD+ to repair cells that become damaged as a direct result of prolonged UV exposure.

• A review published in the International Journal of Molecular Sciences suggests you’ll experience a greater sensitivity to sunlight if your NAD+ levels are depleted because UV rays have an adverse effect on cellular repair processes.

• Maintaining NAD+ levels helps support a family of enzymes called “sirtuins” that help maintain cellular health and repair cellular damage.

All in the family.

Sirtuins are a group of seven enzymes that help regulate overall cellular health like energy metabolism and stress response (e.g., what happens during UV exposure), which are all things that can affect the aging process. A review published in Trends in Cell Biology suggests sirtuins need to lean on NAD+ for help to do this job properly.

These sirtuins enzymes react to the amount of NAD+ in the cells, helping them respond to stress and maintain their overall health. Because we know that NAD+ levels decline as we age, this relationship between sirtuin activity and NAD+ effectively promotes cellular health and healthy aging.

Protect yourself from the sun.

If you do step out into the sun, there a few things you can do to protect yourself:

• Cover up within 10-15 minutes of being in direct sunlight

• Wear sunscreen with an SPF of at least 15+

• Try to limit prolonged sun exposure.

And, if you feel like you’ve been out for too long or show signs of burning or fatigue, there are a few ways you can get back on track. Maintaining a healthy diet, moving your body, or taking a mitochondrial supplement can all boost your NAD+ levels and help you recover more quickly.