Sweat and dehydration are one thing, but extreme heat can impact you in more surprising ways too.
It’s not your imagination: This summer has been exceptionally hot. In fact, 2023 is on track to be the hottest year ever recorded on Earth—at least until 2024, which some climate scientists predict will see temperatures climb even higher.
While it is possible for humans to become acclimated to hot climates after living in one for a long period of time, those who reside in regions that experience dramatic, rapid increases in temperature tend to be more vulnerable to heat-related health problems, according to the National Institutes of Health.
Sun exposure also makes a difference in your health and well-being. According to Asim Shah, MD, professor and executive vice chair of psychiatry and behavioral sciences at Baylor College of Medicine, it can work both ways. Ask anyone who needs to use a sunlamp or deals with a vitamin D deficiency during the winter how important it is to get enough sunshine; but on the other hand: “The ‘everything in moderation’ rule also applies to sunlight,” Dr. Shah says. “A lack of sunlight isn’t good, but during periods of extreme heat, we can get too much sunlight—more than what we need—which isn’t good for us, either.”
Most people understand the importance of staying sufficiently hydrated in hot weather and wearing sunscreen to protect their skin, and many are familiar with the impact heat can have on our mood and mental health, as well as our sleep quality. But that's only the beginning. Here are seven less-obvious ways that too much heat and sun exposure can mess with our body and mind, and what we can do to prevent them.
How Heat Exposure Can Impact Mental and Physical Health
It can cause heat exhaustion and heat stroke.
Being aware of heat exhaustion and heat stroke is one thing, but understanding their signs and knowing how to prevent them is another. These heat-related conditions can sneak up on anyone who’s spending time in environments with high temperatures—even indoors, including warehouses, factories, commercial kitchens, and other workplaces that can easily exceed 90°F.
Rather than viewing heat exhaustion and heat stroke as two separate conditions, Thomas Waters, MD, an emergency medicine physician at the Cleveland Clinic recommends thinking of them as “exist[ing] on a spectrum from not-so-serious, to a significant and life-threatening emergency.” Both cause your body temperature to rise, giving way to other symptoms. Of the two, heat stroke is more severe.
The symptoms of heat exhaustion can include:
Body temperature between 101 and 104°F
Fatigue and weakness
Nausea and vomiting
Anyone experiencing these symptoms should get out of the heat and sun immediately, sip cool water or another hydrating beverage with electrolytes, and try to bring down their body temperature using ice packs, rags damp with cold water, or having them take a cool bath or shower.
In the event that heat exhaustion has progressed to become heat stroke, a person may experience some of the symptoms described above, with these key differences:
Body temperature above 104°F
Dry skin and the inability to sweat
Hallucinations or altered mental state
Confusion, agitation, or aggression
This means calling 911. “Heat stroke is an emergency,” Dr. Waters notes. “It can become deadly very quickly. Heat stroke isn’t something you can just push through, no matter how strong you are.”
Fortunately, heat stroke and heat exhaustion are preventable if you follow the usual advice for staying safe and cool in the heat and sun, including staying sufficiently hydrated, spending time in the shade as much as possible, and listening to your body. “Also, when you’re outside, try to keep your head covered as much as possible, by wearing a hat or a cap—especially one with ultraviolet protection,” Dr. Shah says.
It can make you lose your appetite.
Everyone’s appetite is different, but if you’ve ever noticed that you’re not as hungry when it’s hot, there’s a reason for that.
“During periods of heat exposure, our body attempts to dissipate heat by increasing blood flow to our skin, and through the process of evaporative cooling when sweating,” says Elizabeth Huggins, RDN, registered dietitian nutritionist at Hilton Head Health. “When blood flow is increased to our skin, digestion can slow down, and some people may be more likely to lose their appetite than others, depending on temperature, humidity, duration of heat exposure, and an individual’s medical conditions and medications.”
We can also thank our hypothalamus, which Huggins says is intricately involved in hormonal regulation of our body temperature and appetite. “During and after a meal or a snack, there is a slight thermic effect, [which] increases [our] body heat, as food is being digested and absorbed, so our body may compensate by decreasing appetite at that time,” she explains.
Fortunately, if you don’t have much of an appetite on one particularly hot day, Huggins says it’s not cause for alarm. However, if this is happening on a regular basis during the summer or a heat wave, it’s important to make sure your body gets the nourishment and hydration it needs to function. “Most people find that smaller, less fatty foods and meals are more enjoyable and better tolerated than large or fatty meals,” she explains. Here are a few of her other tips:
Opt for foods that are refreshing, easy to digest, and have a high moisture content, like cold watermelon or a fruit smoothie.
Sip on cold water or another hydrating fluid while eating a meal, instead of guzzling a large soda or alcoholic beverage.
Limit, or better yet, avoid alcohol.
If possible, eat in a cooler location and give yourself time to digest your snack or meal before returning to the heat.
It can interact with many common medications.
According to Georgetown University’s Health Policy Institute, more than 131 million Americans, or roughly 66 percent of all adults, use prescription medications. On top of that, there are others who take over-the-counter maintenance drugs, like allergy medicine, on a daily basis, or pain relievers as needed. And, as Dr. Shah points out, heat- and sunlight-related interactions with common medications are often overlooked.
The interactions typically take one of two forms. First, some medications can make a person’s skin more sensitive to sunlight, leaving them especially vulnerable to sunburns and rashes. “Some antibiotics, like ciprofloxacin, tetracycline, or others of that nature are common examples of this,” he says.
Some of the other drugs that can cause sensitivity to the sun include certain:
Antifungals (e.g. griseofulvin (Gris-PEG), voriconazole)
Antihistamines (e.g. cetirizine (Zyrtec), diphenhydramine (Benadryl), loratadine (Claritin))
Cholesterol-lowering drugs (e.g. atorvastatin (Lipitor), simvastatin (Zocor), lovastatin( Mevacor), pravastatin (Pravachol))
Non-steroidal anti-inflammatory drugs (e.g. ibuprofen (Advil, Motrin), naproxen (Aleve))
Oral contraceptives and estrogens
Retinoids and alpha-hydroxy acids in skincare and cosmetics
Sulfonylureas for type 2 diabetes (e.g. glipizide (Glucotrol), glyburide (Micronase))
However, as the Food and Drug Administration (FDA) notes, not everyone who takes the drugs mentioned above—as well as the others listed on the agency’s website—will experience sensitivity to sunlight. That said, it’s best to take precautions anyway.
“Most of the time, medications that interact with sunlight will include a warning label on the prescription bottle,” Dr. Shah says. “Sometimes we ignore those stickers, but we need to read them because they come in handy.”
Additionally, there are medications that can make some people less tolerant of heat, either by making it harder for their body to regulate its temperature, or causing them to become dehydrated faster than usual. Examples of those drugs include certain:
Antidepressants (e.g. Prozac, Cymbalta, Lexapro, Zoloft, Paxil, Celexa)
Attention deficit hyperactivity disorder (ADHD) medications (e.g. Adderall, Ritalin)
Decongestants (e.g. pseudoephedrine (Sudafed), phenylephrine (Sudafed PE), Oxymetazoline nasal spray (Afrin, Zicam, Dristan, Mucinex))
Diabetes medications (e.g. GLP-1 medications, like Ozempic)
Heart medications (e.g. beta blockers (metoprolol, atenolol) and ACE Inhibitors (lisinopril)
If you’re currently taking any of these prescription medications or over-the-counter drugs, “it’s important to talk to your doctor and discuss your options,” Dr. Shah says.
It can make exercise more exhausting than usual.
Most people understand that hot weather makes us sweat more in general, as well as during exercise, which could increase our chances of getting dehydrated. But what if you’re staying sufficiently hydrated while working out in the heat, and still find that you’re feeling tired and worn out faster than usual? According to David Chesworth, an exercise physiologist and the program director at Hilton Head Health, this is because your body is always working towards maintaining a baseline internal environment: a phenomenon known as “homeostasis.”
“As you might imagine, when exercising in hot weather, the body’s internal core temperature rises,” Chesworth explains. “The homeostatic response to this is your body’s attempt to cool its core temperature to baseline. The way it does this is by sending more blood to the skin. This helps the body to sweat more, which releases heat and cools our core temperature.”
However, when more blood is sent to the skin, there’s less available blood—and, in turn, energy—for the muscles, and they’ll get tired sooner than usual.
“This also means that the heart is working harder to deliver blood to muscles,” Chesworth says. “The body can adapt to exercising in the heat; however, if you are not heat-training-adapted, you will especially feel the fatiguing effects of hot weather, despite staying hydrated.”
It makes you more susceptible to muscle cramps.
Let’s say it’s a hot day, and you’re walking along, minding your own business, when out of nowhere, one of your muscles involuntarily and forcibly contracts for seemingly no reason, causing discomfort, if not in pain. This is what’s known as a “heat cramp,” and it’s a sign your body needs electrolytes.
“People think of hydration as water, water, water, but that alone may not be sufficient,” Dr. Shah says. “You also have to take care of your electrolytes, because when you sweat, not only do you lose water content, but you also lose electrolytes, and you need to replenish those.”
So what does that have to do with muscle cramps? “Electrolytes are charged particles in the muscle’s cells that, when balanced, allow for a proper muscle contraction to take place,” Chesworth explains. “Therefore, if there is an electrolyte imbalance, you are likely to experience a cramp.” While sodium, magnesium, potassium, and calcium are all important electrolytes for recovery after physical activity, he notes that sodium is the one we lose most when we sweat.
Generally speaking, if you are consuming three-to-five servings of whole fruits and vegetables most days, and are in the habit of drinking water throughout the day, Chesworth says that you won’t need to supplement with electrolytes before exercise. However, if you’re exercising for longer than an hour—or less than that if you’re not accustomed to exercising in hot weather—he says that it’s wise to stay hydrated with an electrolyte source, like adding electrolyte tablets to water, or Gatorade, Prime, or another electrolyte sports drink.
It can lead to brain fog and make it difficult to focus.
A handful of studies conducted at schools, universities, and workplaces have confirmed what many of us already knew: Hot weather can make it harder to concentrate and be productive, and reduce our reaction time and accuracy when performing tasks. There are several possible explanations for these impacts on our brain’s ability to function, including poor sleep quality in environments without air conditioning, increased cortisol (and therefore stress) levels, and simply being distracted by the discomfort of feeling too hot.
Plus, according to Dr. Shah, a serious lack of electrolytes can cause feelings of confusion or disorientation. “But those are extreme situations,” he notes. “It’s important to take precautions to prevent yourself from going that far."
It may trigger skin rashes, inflammation, and infections.
It’s no secret that without sufficient protection, sun exposure can be harmful to skin, causing everything from sunburns and visible surface damage. But it would be a mistake to ignore the ways that spending time in a hot environment, whether indoors or outdoors, can affect our skin in other ways—starting with heat rash.
Also known as “sweat rash” or “prickly heat,” heat rash is typically associated with babies and young children, but adults can get it as well, especially when it’s humid. A heat rash looks like a group of small pimples or blisters, and forms when the ducts that transport sweat to your pores get clogged and trap your sweat, causing skin inflammation.
Heat and excessive sweating can also result in another inflammatory skin condition known as “intertrigo”: an itchy reddish-brown rash that’s mostly flat, but may include some small bumps. It tends to form in skin folds or creases, or other body parts where heat and moisture can lead to skin-to-skin friction, like the neck, groin, armpits, and under or between the breasts. Though some believe that intertrigo is a bacterial or fungal infection, that’s not the case. While the initial inflammation itself isn’t an infection, the damage it can cause to your skin—especially if you scratch it because it itches or burns—combined with the warmth and moisture, creates the perfect conditions for bacteria or fungus to grow, resulting in a secondary infection.
Fortunately, it’s possible to prevent heat rash and intertrigo. In addition to spending as much time in climate-controlled environments with good airflow as possible, it also helps to wear lightweight loose-fitting clothing made from natural fabrics, like cotton, and being sure to dry off completely after showering or working out.
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