Without the sun, no living thing could survive on Earth, including humans. The sun allows food to grow and helps your body produce vitamin D. Why, then, does this life-giving star also make you feel tired? Perhaps you’ve wondered this after spending a day in the sun, and ending upcompletely exhausted.
There are several reasons why direct sunlight tiresyou out. The first is that your body doesn’t want to heat up. Therefore, it has to use a lot of energy to coolitself downand maintain its ideal temperature, 37°C. It does this by sending blood to your skin’s surface and by sweating. If you feel extremely tired in the sun, it’s a sign that it’s time to take a rest and cool downlest you sufferheatstrokeor even die.
Another factor is dehydration, or lack ofwater. When you sweat a lot, your body loses water. As a result, your blood becomes thicker, which makes it harder for your heart to pump, meaning that less oxygen will be delivered to your body. This reduction of oxygen will make you feel even more tired. This is why it is soimportant to drink lots of water when you spend time in the sun. Yet another factor is sunburn, which is your skin’s reaction to the UV (ultraviolet) raysin sunlight. Your skin turns red as a form of protection, but this process is also tiring for your body’s immune system.
As you can see, the sun is both your enemy and friend. Exposing yourself toits warming rays on a daily basisis good for you. But tirednessis your body’s way of telling you when it has had enough sunlight for the day.
1. What is the main idea of the passage?
(A) Sunburn is a sign that your body is healthy.
(B) There are health benefits to getting enough sunlight.
(C) Any direct exposure to the sun is bad for your body.
(D) Tiredness serves as a warning that you’re getting too much sun.
2. Which of the following is NOT a reason why the sun tires you out?
(A) It forces your body to use energy to avoid overheating .
(B) It makes your skin burn, which requires energy.
(C) It increases the level of oxygen in your blood.
(D) It causes a reduction of water in your body.
3. Why does the author call the sun an enemy and a friend?
(A) Sunlight feels warm but actually cools your body.
(B) The sun is good for you, but it can also be harmful.
(C) People want to enjoy the sun every day but shouldn’t.
(D) The sun actually does more harm than good to humans.
