Short answer : the causes explaining the feeling of fatigue following prolonged exposure to the sun are multiple: self-regulation of the body at 37 ° c, dehydration, sunburn, excess activity.
A summer sunbath on a Normandy beach, a walk under the southern pines or a Sunday morning jog, whatever the situation, prolonged exposure to the sun affects your body . Sport or not, you have all felt this feeling of fatigue after an afternoon spent in the sun. Let’s take a close look at how your body works to understand the reasons.
Your body goes out of its way to cool you down
“ Man is homeothermic , it maintains its fixed core temperature, regardless of the outside temperature “explains Jean-Louis San Marco, professor of medicine at the University of Marseille and initiator of the first heat wave warning system, in Marseille, during the scorching summer of 1983 . The optimal outside temperature, which requires the least effort, is between 17 and 23 ° C. Above, the body strives to regulate its temperature to 37 ° C. And for this, it can help with perspiration to allow the heat to dissipate.
Perspiration, temperature regulator
Sweating causes loss of electrolytes, substances that your body needs for a wide range of functions, including muscle and brain. Deficiency of these vital elements can cause your muscles to weaken causing muscle cramps or convulsions, anxiety and sleep problems, and extreme fatigue.
Dehydration, the cause of all ailments
Dehydration, also called heatstroke or “heat stroke”, is the unfortunate result of sweating when the human body is subjected to prolonged sun exposure, thus experiencing a imbalance between water intake and loss . Wrongly, we think that dehydration happens most often during physical activity. Remaining motionless under a blazing sun without drinking a drop of water is just as dangerous and some franks of the population are more at risk, especially children and seniors. During dehydration, it is more difficult for the heart to get blood to the brain and muscles, causing headaches, dizziness and great fatigue.
Watch out for sunburn
Sunburn is also the cause of a feeling of fatigue during prolonged exposure to the sun. The burn from sunburn can be painful but also exhaust you because it increases your body temperature who seeks to keep his internal temperature at 37 ° c.
What should be done to limit this fatigue?
To the contrary, there is no time limit guaranteeing exposure to the sun without fatigue. This one depends on your age, weight and degree of hydration. However, certain behaviors can slow down or accelerate this fatigue and are applicable to everyone:
- Have a good food hygiene . The heavier you eat, the more energy it will take from your body for digestion, which will tire you twice as much if you are in the sun right after eating.
- You protect as much as possible from the sun : sunscreen, hat, parasol. Stay in the shade as much as possible during the hottest hours of the day (between 11 a.m. and 5 p.m.).
- Drink water regularly without waiting for the feeling of thirst all day long. To compensate for this loss of water, which is largely evaporated through perspiration, your body needs to compensate. How much ? Normally, a person who does not exercise in mild temperatures should drink 1.5 to 2 liters of water. Under high heat, the amounts should be increased. However, beware of overconsumption of water for the elderly who eliminate water much less easily and can cause edema. The easiest way to control enough water in your body is to check if your urine is transparent . If so, it’s won!
- Avoid caffeine and alcohol that promote dehydration of the body.
- Think of you immerse in water when possible to help your body regulate its temperature.
Sources:
- sleep.org (Three Reasons That the Sun Makes You Tired)
- mic.com (Why being out in the sun makes you tired, according to experts)
- menshealth.com (5 Reasons the Sun Makes You So Damn Tired)
- bathing.sante.gouv.fr (Heat and dehydration – FR)
