With summer in full swing, I thought it might be a good time to review some basics about staying healthy and cool in the heat.

The human body’s main defense against heat is sweating. Sweat evaporates, which cools the skin, but it is less effective when the humidity is high, which is why it’s more uncomfortable during those hot, muggy summer days and nights. But you can help keep yourself cooler by taking a few simple measures.

Clothing matters. Light-colored clothing reflects sunlight, whereas dark clothing absorbs it. The looser fitting your clothing is, the more air can circulate, so a button-down shirt may be a better choice than a T-shirt or tank top. Modern wicking “performance” materials like polyester and polypropylene draw moisture away from the body without absorbing it into the fabric, permitting evaporative cooling. They also drive from the inside out, so you tend not to feel as wet. You can even pour water over this material, cooling yourself, and it will feel dry in just a couple of minutes. A wide-brimmed hat provides shade and reflects sunlight, but any hat is better than none.

Obviously, keeping in the shade will make a big difference. Try to limit exertion during the hottest part of the day. Alcohol and caffeine should be avoided as they both increase the amount of urine produced.

Hydration is incredibly important. Because you are sweating in the heat, you can lose a surprising amount of water and salt. People exerting themselves on a really hot day can lose up to 10 quarts of water a day, so it’s easy to fool oneself into thinking that drinking one quart of water on a hot summer day is keeping up with your fluid loss. You can monitor your state of hydration by paying attention to your urine. If you are not peeing, this is a bad sign. When the body gets dehydrated, your kidneys compensate by making more-concentrated urine, which looks a deeper yellow. If you see light-colored urine you can deduce that your state of hydration is good, but darker yellow urine is a warning sign. Breathing through your nose not to your mouth can be helpful in preventing water from evaporating through your lungs. The nose has a system allowing exhaled water to get dried out and inhaled water to get moisturized. This is especially important in dry or desert environments.

While water is important to hydration, electrolytes (salts) are just as important. The body monitors two things regarding fluids: The amount of fluid in the body (how full the tank is), and how concentrated the salt is in your bloodstream. When you sweat you lose both water and salt. If you replace only water, the salt concentration in your bloodstream goes down; you are essentially diluting yourself. Having a low salt concentration in the bloodstream causes muscles, nerves, and brain cells to malfunction, so if your body has to pick between filling up the tank or not diluting itself, it will choose not diluting itself. Your kidneys will urinate out all the water that you drank unless you replace the salt. Gatorade (the original kind, not the ones that are more like soft drinks) or Pedialyte are great ways to maintain hydration because they include electrolytes. If you don’t have access to that, a quart of half water/half juice and a generous pinch of salt can replicate Gatorade to some degree. You can also eat salty foods along with the water that you drink. Some sugar or starch also helps to absorb water. 

In addition to darker urine, another common symptom of dehydration is known as orthostatic hypotension. This is the feeling you get when you “stand up too fast” and you feel dizzy, lightheaded, or even have a graying out of your vision. Because the fluid levels are low, or because blood tends to get diverted to the skin to release heat, your blood pressure drops when you stand up, and blood (which must work against gravity) is literally not making it all the way up into your brain. Standing up and holding onto something will not remedy this, and you may be at risk for losing consciousness, falling, and hitting your head. The quickest, easiest remedy for this is to bend over at the waist or to sit back down. Bending over means that your heart is pumping blood horizontally not vertically: the brain now gets enough blood flow and you do not lose consciousness. Straighten up slowly, which gives the body a chance to adjust, and replace fluids and electrolytes as soon as possible.

The most dangerous consequence of heat and fluid loss is heatstroke. Heatstroke constitutes a severe medical condition that mandates immediate medical attention.

The symptoms and signs of heatstroke include:

1. High body temperature: A central body temperature of 104 F (40 C) or more, ascertained with a rectal thermometer, marks the primary sign of heatstroke.
2. Altered mental state or behavior: Some individuals might experience seizures, hallucinations, difficulties in speaking or understanding spoken words, slurred speech, lack of coordination, or even falling into a coma. People with heatstroke may appear drunk, but do not assume someone in this condition on a hot day is “just drunk.”
3. Alteration in sweating: the skin may present as hot and dry. Contrastingly, with heatstroke triggered by strenuous exercise, the skin could seem moist.
4. Nausea and vomiting.
5. Flushed skin.
6. Rapid breathing: Breathing may become swift and shallow.
7. Racing heart rate: Pulse rate might significantly increase as the body responds to heat stress, which places a huge burden on the heart in an attempt to cool the body.
8. Headache: Throbbing headaches may be experienced.

It’s crucial to remember that heatstroke constitutes a life-threatening emergency. If an individual is suspected to be suffering from heatstroke, medical help should be obtained immediately. Until help arrives, the individual should be relocated to a cooler location, their excess clothing should be removed, and attempts should be made to cool them down by applying cool cloths or having them ingest cool water if possible. However, beverages containing alcohol or caffeine should be avoided.

The summer can be the best time of year, as long as you keep your cool and stay hydrated!