So THAT'S Why You Feel So Tired After Being Out In The Sun

Being in the sun is hard work ― or so your brain and body seem to think.

Even when you’re just relaxing on a lawn chair by the pool or at the beach, you may have noticed you feel extra sleepy after being outside in the sun for hours. Why does this happen?

“The sun causes several changes that result in our bodies needing to work harder, which leads to fatigue,” Dr. Heather D. Rogers , a board-certified dermatologist and founder of Doctor Rogers Skin Care, told HuffPost.

We talked to doctors about how the sun affects our bodies and why it can make us feel drained — and tips to avoid fatigue and spend time outside safely.

Your body is working hard to regulate its temperature.

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

There are three things your body is doing to try to cool itself down: You’re breathing faster, your heart rate is increasing and you’re sweating more, he explained. These all require extra energy from your body, which can leave you feeling fatigued.

“In extreme cases when our bodies cannot effectively cool down, people can develop hyperthermia or heat-related injury and illnesses,” said Dr. Shengyi Mao , an internal medicine physician at The Ohio State University Wexner Medical Center.

Heat exhaustion includes symptoms such as fatigue, dizziness, nausea and headache, according to Mayo Clinic . If heat exhaustion isn’t treated, it can lead to heatstroke , which is the most serious heat-related illness and requires emergency medical care.

Your body is