Why Does The Sun Make You Tired
Vitamin D is the final product created by the body when the ultraviolet radiation from sunlight encounters 7-dehydrocholesterol in the skin. A good supply of vitamin D has many health benefits, including contributing to bone health, bolstering your immune system, and even potentially help reduce cancer cell growth. Despite the benefits of sunlight, it also has several other effects on the body that can leave you lethargic or sleepy. Being aware of these will equip you to counteract them and to enjoy your time outside in the sun.
Dehydration
Being out in direct sunlight can make the air temperature feel up to 10 to 15 degrees warmer. It's a misconception that the air temperature itself is actually warmer, but the body will still perceive the added solar radiation as heat energy, which means your body will perspire to cool itself down. Dehydration can range from nominal to severe, but one of its principal symptoms is fatigue or malaise, and worse yet, you might not realize you're dehydrated until it has already begun to progress. If you are out in direct sunlight, ensure you drink water and consume electrolytes frequently to ensure you are replenishing your body and meeting its needs.
Sunburn
Sunburn is an inflammatory response to damage from the sun's radiation, which also raises your body's temperature. Sunscreen is an absolutely essential part of your kit to avoid fatigue from the sun's rays (not to mention avoiding the painful sunburn the following day!) Reapply sunscreen every few hours to ensure a baseline level of coverage over your entire body, as it wears off over time -- especially after swimming.
Natural Response
There is evidence to suggest that the radiation from sunlight triggers your immune system, which is something your body will then have to balance among all the other demands placed on it. There's nothing wrong with giving your body a break if it needs it by seeking shady areas, using sun umbrellas, or wearing sun hats or other clothing to help cover up your skin.
The Benefits of Sunlight
This is not to say that sunlight isn't energizing as well -- only that there are considerations to manage to ensure your day outside is a healthy, invigorating one. Beyond the benefits of vitamin D, sunlight also triggers your body to release serotonin, which can help regulate your mood and fight depression and anxiety. A positive mood will help motivate you, which will help you feel more energetic and lively. Better regulation of serotonin can also help your body produce melatonin at night, which will improve the quality of your sleep and even make you feel more energetic the day after.
There is also evidence that exposure to sunlight can help regulate your blood pressure. A study found that nitric oxide in the skin reacts to sunlight, which dilates blood vessels and makes it easier for blood to pump through the body. While it is possible to get too much of a good thing, a balanced amount of sunlight can be an easy and fun way to take care of your heart, which will certainly help you feel more energetic.
Thoughtful exposure to sunlight can even help the body's natural healing process, as it has anti-inflammatory and antioxidant properties. The less your body has to focus on, the more lively you will feel, and sunlight may provide a natural remedy for aches and pains.
Conclusion
Although there are several reasons why you feel you might lose energy in the sun, the truth is these can be counteracted. A careful, balanced approach to the sun will allow you to avoid these pitfalls and enjoy all the health benefits a day outside can offer.