It's hot outside — and it's about to get a lot hotter for millions of Americans this weekend. The National Weather Service has issued excessive heat watches, warnings and advisories in the Plains, Midwest and parts of the East Coast. More heat alerts are expected later this week, as temperatures in cities like Chicago, Philadelphia and Washington, D.C. could reach 100 degrees.
What can you do to stay cool? Aside from staying indoors, in air conditioning, keeping your body well hydrated is key to staying healthy during a heat wave.
Heat can sometimes be very subtle in how it affects the body. If you're out in the sun, it can take just 30 minutes or up to a few hours for the heat to cause dehydration, nausea or trouble concentrating, said Dr. Corey Slovis, chairman of emergency medicine at Vanderbilt Medical Center.
Dehydration is a serious health concern. A recent study published in the American Journal of Public Health found that more than half of all children and adolescents in the U.S. aren’t getting enough water.
“People don’t realize the amount of fluid they can lose in the heat, or while exercising,” explained Michael F. Bergeron, Ph.D., and president and chief executive officer of Youth Sports of the Americas. “And it’s important to note that your hydration needs are very individual,” said Bergeron.
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This health issue is more serious than you might think and could land you in the hospital.
Heat stroke occurs when the body temperature gets above 105 degrees. "One of the earliest signs of a heat-related illness is just not feeling right," said Slovis. "There's no one specific symptom."
How much liquid do we need each day? It depends. Here are a few signs you might be dehydrated and tips to stay healthy all summer long.
1. Increased thirst and a dry or sticky mouth
"If you feel thirsty, you're already dehydrated," explained Dr. Laura Goldberg of Cleveland Clinic Sports Health. The easiest remedy is to start drinking water (and beverages with electrolytes) as soon as you notice this, but try not to let yourself get to this point.
The best way to prevent this from happening is to meet your daily hydration needs, for women, the National Academy of Sciences recommends 2.7 liters of water a day (about 11.4 cups), and for men, 3.7 liters (15 cups). Try to drink more water if you've spent excessive time in the sun, or exercising.
2. Signs of fatigue, confusion or anger
Studies have found that mild levels of dehydration can affect your mood and cognitive functions. This is especially common in the young or elderly, who may seem less alert, or forgetful.
A study from the University of Connecticut Human Performance Laboratory found that even mild dehydration can alter a person mood, energy and ability to think clearly. The researchers defined mild dehydration as an approximately 1.5% loss in normal water volume in the body — and the adverse reaction is the same whether you're exercising or sitting still.
3. Dry eyes or blurred vision
"When you've been exercising for a long time, you're sweating and your overall body fluid goes down — this can result in dry eyes or blurred vision," said Goldberg, who also noted that any part of the body that is normally moist is going to feel dry or irritated.
"Monitor your hydration levels and make sure you're drinking throughout any form of exercise," she explained further.
4. Headaches or disorientation
Dehydration can result in a headache or migraine, light headedness or delirium. “I’ve seen marathon runners running in zigzags because they’re dehydrated. You can’t make decisions and feel delirious,” elaborated Goldberg.
“You may also experience weakness, dizziness, or nausea, because the body doesn’t have enough fluid to send to other parts of the body. This could also result in heat exhaustion. You can collapse if you don’t stop exercising and cool down,” warned Bergeron, who also added that these specific symptoms can also be signs of over hydration, so be aware of how much you’re drinking.
5. Muscle cramps
“If you’ve been exercising, it’s natural for your legs to feel tired, but if it’s more than that and you’re experiencing muscle cramping, that’s a serious sign of dehydration,” Goldberg explained. This is because of the loss of water and salt in the body — you also might experience tightness in your muscles, instead of cramping.
“Wandering and progressively widespread muscle cramping is a certain clue of a sodium deficit and dehydration in the fluid spaces surrounding certain muscles,” Bergeron elaborated. “But don’t confuse it with an overworked muscle which would just affect a small area.”
To prevent this from occurring, it’s important to drink sports beverages that contain sodium, or snack on salted pretzels or low-fat cheeses. The sodium helps your body to re-hydrate and retain the water.
6. Lack of sweat
According to Goldberg, this is one of the more serious signs of dehydration. It means your body is in dire need of water. Though, on the other hand, Bergeron notes that more likely it may be a sign of overheating or heat stroke — though either can occur in the presence of continued sweating. Either way, it’s crucial to cool down rapidly if you’re not sweating anymore.
7. Dark urine
“Straw-colored or light yellow urine means you're properly hydrated. If your urine is dark, or if there’s blood in your pee, you need to stop exercising immediately,” warned Goldberg. Notably, perfectly clear urine may mean that you are over-hydrated.
“Dehydration can lead to hyperthermia and a fever-like symptoms (e.g. chills) because over-heating can alter your body's normal temperature 'set point,'” explained Goldberg. Excessive overheating is an urgent red flag. Stop exercising immediately, take an ice bath and hydrate.
9. Shriveled and dry skin
If your skin is hydrated, it will appear doughy. If you’re dehydrated, your skin will lack elasticity and won’t bounce back. “If you pinch your skin and it appears thin and doesn’t melt back onto your body quickly, you’re dehydrated,” said Goldberg.
Some key things to remember when exercising in the summer is that the longer you’re working out, the more water you need. Also, plain water is good for you, but a combination of water, electrolytes and sodium is really the best way to stay hydrated.
It’s also crucial to understand that hydrating properly isn’t 100% preventative, if you’re working too hard and too long in the summer heat, you can still overheat no matter how much water your drinking. So be aware of your body, and stop what you’re doing if you notice any of these symptoms.
This story first appeared on TODAY.com. More from TODAY: