Here’s Why You’re Tired After a Day in the Sun (Even on a Lounge Chair!)

You spent half the day on a deckchair by the sea, in peace and quiet, but you find yourself exhausted at the end of the day? Where does this feeling of fatigue come from, which falls on you, while you are on vacation? In the HuffPost USdoctors have answered this seasonal riddle. And they put forward a global explanation: the sun causes changes that force our bodies to function differently.

Your body needs to regulate its temperature

“Even if [vous] are lying by the pool… your body is constantly working to lower its temperature to a normal level… when you are outside in the heat”explained Dr. Patrick Mularoni, emergency physician and medical director of sports medicine at Johns Hopkins All Children’s Hospital.

Basically, your body starts doing two things in the sun: your heart rate increases and you sweat more. All of this requires extra energy from your body, which can make you feel tired. Heat exhaustion includes symptoms like fatigue, dizziness, nausea, and headaches. Beyond that, it’s heat stroke.

Your body is trying to repair the damage caused by UV rays.

“Too much ultraviolet radiation from the sun… is very stressful for our skin”explained Dr. Shengyi Mao, an internal medicine physician at Ohio State University Wexner Medical Center.“When we are exposed to ultraviolet light, our bodies have to fight and repair cellular damage, which can lead to feelings of fatigue, not only immediately but also afterwards.”

Overexposure to UV rays can also weaken the body’s immune system and the skin’s ability to protect itself against infections, according to the U.S. Environmental Protection Agency.

Your body doesn’t have enough water to function properly

“In the sun, we lose water more quickly through heat and evaporation, so we are more likely to dehydrate” continues Dr. Mao. “When we are dehydrated, our bodies work harder to accomplish [leurs] normal functions, such as pumping blood, which can make us tired.”

Drinking alcoholic and caffeinated beverages can still “disrupt your water balance” and make you even more dehydrated.

Your body releases accumulated stress

Hanging out by the pool or at the beach can give you a chance to finally slow down and unwind from the usual stress. Your body may recognize that it’s behind on sleep and can finally recover and relax, which can make you feel sleepy, adds Dr. Mularoni.

What can you do to avoid sun fatigue?

Of course, all of this doesn’t mean you shouldn’t get outside this summer! Light and sunshine are essential to your health, too. Exposure to sunlight helps your body produce vitamin D, which is essential for your immune system and bone health, for example. Sunlight has also been shown to increase serotonin in your brain and improve your mood.

There are, however, some tips to enjoy it without feeling exhausted.

• Don’t wait until you’re thirsty to drink water. Drink water before you feel thirsty. When you feel thirsty, drink more than you think you should. And remember to hydrate before going out in the sun and during any time you spend outside. Also limit your intake of dehydrating beverages, such as caffeine and alcohol.
• Protect your skin from sunburn. Use a sunscreen labeled broad spectrum (protects against both UVA and UVB rays) and with an SPF of 30 or higher. When outdoors, reapply every two hours or after swimming or sweating. Also wear protective clothing, sunglasses, and hats, and avoid midday sun exposure.
• Refresh your body. Wear light, loose clothing, drink a cool drink, swim in the pool, use a portable fan and seek shade.
• Finally, watch for signs that you need to see a doctor. The best way to determine whether you’re just tired or experiencing more serious symptoms of heat exhaustion is to see how you feel once you’re out of the heat. Get yourself into a cool environment and drink plenty of fluids. If you still feel sick within 15 minutes, you should see a doctor, experts advise.

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