TIME Diet/Nutrition

You Asked: Why Do I Get Hangry?

Hangry - Peter Oumanski
Peter Oumanski for TIME

Blame your glucose-deprived brain for your rotten mood.

Long-term couples know all too well the perils of the early evening hours: that touchy time after work but before dinner hits the table.

It’s prime time for getting “hangry”, a handy portmanteau for hungry and angry. People commonly feel an uptick in anger or aggression when they’re hungry, says Dr. Brad Bushman, a professor of psychology at Ohio State University. “The brain needs fuel to regulate emotions, and anger is the emotion people have the most difficulty regulating,” he explains.

Your brain’s primary fuel source is glucose, which your body makes from the foods you eat. And as far as fuel consumption goes, “the brain is a very demanding organ,” Bushman says. While your brain constitutes just 2% of your body weight, it uses 20% to 30% of the energy you consume, he says.

MORE: Here’s What Eating Does To Female Desire

So why do you feel hangry in the evening, but not first thing in the morning when you’ve gone the whole night without food? Willpower and self-control tend to flag as the day wears on, which further torpedoes your mood, Bushman says.

That’s bad news for your partner. Bushman’s research has shown that compared to well-fed couples, glucose-deprived people tend to stick more pins into voodoo dolls meant to represent their spouses. The underfed study participants were also more likely to blast their partners with unpleasant noises.

When your brain is struggling to control its emotions, you’re likely to lash out at the people with whom you feel most comfortable, Bushman and his colleagues concluded. So loved ones and close friends tend to bear the brunt of your glucose-starved brain.

There seems to be another, deeper layer to your hunger-induced emotional fragility.

Some of the same appetite hormones that signal to your brain It’s time to eat! also fire up those brain regions linked with stress and anxiety, says Dr. Paul Currie, a professor of psychology and neuroscience at Reed College in Portland, Oregon. In fact, Currie says some of those regions overlap.

MORE: The 14 Worst Kinds of Late People

All of this makes sense, he says, when you look at the necessity of food in “evolutionary” terms. “If you’re an animal and you’re hungry, you need food to survive,” he explains. “So it’s natural that you would feel anxious and irritable and preoccupied until you’ve met that need.”

What’s more, this stress-hunger crosstalk may go in both directions. Research has found that people tend to reach for food (especially energy-dense junk food) when feeling stressed.

Of course, the chemical and neuronal processes going on in your hungry brain are complex and vary from one person to another, Currie says. So while you may have no problem keeping your cool before dinner, your friend may be an anger-grenade with a pulled pin.

Fortunately, there’s a simple solution: eat something. If you know your mood tends to plummet before dinner, a preemptive afternoon snack that includes some carbs and protein—like peanut butter and apple, or some yogurt with berries—can help you hold onto your typically sunny disposition.

TIME Exercise/Fitness

You Asked: Does Compression Gear Really Work?

Compression Clothing
Illustration by Peter Oumanski for TIME

It’s the latest craze in active wear. But so far the known benefits are iffy.

From shorts and socks to sleeves and tops, athletes everywhere—amateur and professional alike—are squeezing into super-tight “compression” garments in an effort to boost performance and recovery.

While pinpointing the start of a trend is tricky, the compression craze seemed to spark back in 2001, when NBA star Allen Iverson scored 51 points the first night he wore a long compression sleeve on his right arm. Iverson’s doctor had improvised the sleeve to treat Iverson’s swollen, bursitis-stricken elbow. But after seeing “AI” light it up, other players quickly adopted the accessory.

Many of today’s popular basketball players, including LeBron James, still wear compression sleeves or leggings. And the trend has spread to other sports. Along with Nike and Under Armour, upstarts like 2XU and Tommie Copper have blossomed as compression gear manufacturers.

By squeezing and compacting the flesh of your arms, legs, or torso, these garments supposedly increase blood circulation, which helps deliver more oxygen to your muscles while speeding the removal of acids and the other byproducts of physical activity. There are other purported mechanisms of action, all of which supercharge performance while speeding recovery. That’s the theory, at least. The only thing missing is the proof.

“So far there is little evidence to suggest that wearing compression garments during an event can improve performance,” says Dr. Mike Hamlin, an associate professor of exercise and sports science at New Zealand’s Lincoln University.

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Hamlin has studied the effect of compression garments on short-term recovery. And while his research observed recovery improvements among rugby players who wore compression leggings, those improvements only came from donning the leggings for 24 hours straight following exercise. Other researchers have found similar benefits among weightlifters who slipped into compression body suits, but only when those suits were worn continuously for more than a day following exercise.

Hamlin mentions one 1996 study that found trained volleyball players were able to increase their average—but not maximum—leaping height when wearing compression shorts. But he says there’s “little evidence” that endurance athletes perform better while wearing compression tights and tops. A recent study from Indiana University looked into lower-leg compression among distance runners and failed to find meaningful gains.

Which takes us back to Allen Iverson and his sleeve. Iverson’s doctor improvised the arm compression as an aid for the player’s inflamed elbow—not to boost Iverson’s performance. And when it comes to medical conditions that involve swelling or poor blood flow, compression is still a “mainstay” of treatment and recovery, says Dr. Thomas Wakefield, a professor of vascular surgery with the University of Michigan Health System.

Particularly for lower body blood clotting and venous circulatory issues, Wakefield says compression garments are helpful either in place of or in addition to blood thinning drugs and other forms of treatment. There’s some evidence compression may help control muscle cramps and restless leg syndrome, though Wakefield says its unclear whether compression might be helpful.

MORE: How Exercise Helps Curb Alzheimer’s Symptoms

While mixed, there’s also some evidence that compression can provide a small performance benefit when it comes to explosive movements: a basketball player leaping repeatedly for a rebound, say, or a soccer player suddenly sprinting a few feet for a loose ball. But a 2013 review of the existing research on compression doesn’t rule out the possibility that the placebo effect may explain these performance gains. (You can’t really trick an athlete into thinking she’s wearing compression garments if she’s not, the authors of that review write.)

So here’s the compression gear story, compressed: there are certainly medical conditions for which compression clothing can be beneficial. And when worn for lengthy periods—a day or more following exercise—compression appears to help with muscle recovery.

But for now, the question of whether compression gear can amp up your athletic performance is still up in the air.

TIME Mental Health/Psychology

You Asked: Why Do I Blush So Much?

You Asked Why Do I Blush
Illustration by Peter Oumanski for TIME

Blame the company you keep and the color of your skin, among other factors.

Human beings are the only animals that blush. And try as we might, there’s no simple way to suppress it. In fact, trying to hold back a blush is a pretty good way to intensify it, says Dr. Corine Dijk, a clinical psychologist at the University of Amsterdam.

When you feel self-aware or embarrassed, your nervous system sends a signal to muscles in your face instructing them to relax, Dijk says. That relaxing allows small veins in your skin to dilate, which in turn causes blood to pool and your cheeks to redden. (Dijk says blushing shouldn’t be confused with the “flushing” some people experience when angry, which results from a different physiological mechanism.)

If you’re fair skinned, your blush will be more visible than if you had darker skin, says Dr. Peter Drummond, a social scientist and blush researcher at Australia’s Murdoch University. Some hormonal or anatomical quirks—stuff that’s just part of your unique internal architecture and chemistry—could also make you more or less likely to blush, he adds.

But social discomfort really brings on the blushing. Times of embarrassment, guilt or self-consciousness—or some combination of all three—are when your cheeks produce their mortifying rosettes. So if you’re the type who’s quick to feel embarrassed or self-conscious, you’re probably the type who blushes a lot, says Dr. Marije aan het Rot, a behavioral scientist at the University of Groningen in the Netherlands.

Research suggests certain situations are likely to amp up those blush-inducing emotions, aan het Rot says. If you feel inferior to the people around you—either socially or professionally—you may be quick to feel self-conscious (and quick to blush.) People with social phobias often blush at higher rates than those more comfortable in public, aan het Rot adds. Like so many confounding psychological conditions, fearing a thing—in this case, a blush—makes the thing more likely to happen.

Research also suggests being the subject of scrutiny, even if you have no reason to feel ashamed or embarrassed, is enough to launch a rosy reaction. Prolonged eye contact alone can be a blush trigger, Drummond’s experiments have shown.

On the other hand, feeling unconcerned or uninterested in what other people think of you tends to lower the likelihood you’ll blush, Dijk says. While tough to study, it’s possible that by raising your own social or professional status—or by strengthening your disregard for what others think of you—you may blush less often.

However interesting (or discouraging) all of this may be, none of it explains why people turn red when shamed or embarrassed. What utility does your blush serve, and why did we develop the ability to blush in the first place?

There are theories, but not answers. It’s possible that, like a built-in polygraph, your blush is an involuntary admission of wrongdoing. “When you blush, others know that your emotional experience is true and sincere,” Dijk says. That may sound unappealing, but it has its benefits. “When people blush in an embarrassing or shameful situation, they are more likely to be seen by others as likable and trustworthy than if they had not blushed,” aan het Rot says.

In this way, blushing may have developed as a way for humans to better communicate sincere regret or contrition. It’s also possible your blush is just a byproduct of your body’s attempts to cool your brain when blood rushes to your head in embarrassing situations.

What isn’t in doubt is that pretty much everyone views their own blushing as an undesirable habit—though maybe we shouldn’t. Blushers are, in many situations, viewed “favorably,” aan het Rot says.

Keep that in mind, and you may just blush less as a result.

TIME Diet/Nutrition

You Asked: Should I Take Turmeric Supplements?

Turmeric
Illustration by Peter Oumanski for TIME

The root’s potential health benefits are powerful. But questions remain about how best to take the stuff.

From teas and juices to capsule supplements, turmeric is popping up everywhere these days. And for good reason: Curcumin—a molecule found in turmeric that gives the root its distinctive orangey-yellow hue—appears to be a potent inflammation blocker.

That’s big, because inflammation causes or contributes to almost every major disease, including cancer, cardiovascular disease, diabetes and depression, says Dr. Bharat Aggarwal, professor of medicine at the MD Anderson Cancer Center at the University of Texas. “Wherever inflammation is a problem, curcumin may be helpful,” Aggarwal says.

The chemistry of chronic inflammation is complex. But in very simple terms, a signaling protein called tumor necrosis factor alpha (TNFα) plays a large role in driving systemic, disease-causing inflammation. Pharmaceutical drugs that block or inhibit TNFα are now being used to treat inflammatory bowel disease, psoriasis, arthritis and many other diseases. Like those drugs, curcumin seems to lower TNFα, Aggarwal says.

He hedges with terms like “seems” and “may” because, while promising, a lot of the research pointing to curcumin’s benefits has involved animals or lab work—not people. “If rats and mice were perfect indicators of a treatment’s effectiveness, every disease would be gone by now,” Aggarwal says. “But I’ve been working with curcumin and turmeric for 25 years, I’ve seen and studied the effects, and I can’t deny the benefits I see.”

He’s not the only one. Dr. Greg Cole, associate director of UCLA’s Mary S. Easton Center for Alzheimer’s Disease Research, has spent years studying the use of curcumin as a treatment for brain diseases. Cole says Alzheimer’s is associated with the build-up of plaques in the brain, and “curcumin seems to reduce these plaques.” “That’s a real phenomenon we can see and measure,” he adds.

In India, where turmeric is a mainstay of the national cuisine, Alzheimer’s appears to be less common than in the U.S., Cole says. Genetics and other lifestyle factors make it tough to credit curcumin alone. But again, the evidence is promising.

So why isn’t every doctor from Memphis to Mumbai telling her patients to take a curcumin supplement? First of all, there’s no expert consensus on how much of the stuff you’d have to get into your system to see health benefits. Both Aggarwal and Cole say effective dosages will likely vary from person to person and wouldn’t be the same when it comes to the treatment or prevention of various diseases.

“I tell people to take 500 mg a day in capsule form to keep the doctor away,” Aggarwal says. But that’s more of an educated guess than an evidence-backed finding, he adds. (You’d have to swallow a teaspoon or more of ground turmeric to get that much curcumin.)

Cole says your body may struggle to absorb curcumin if you’re ingesting it on its own. “It’s not water soluble, so 99% of it goes right through you,” he explains. Mixing curcumin with fat seems to supercharge absorption rates. And Cole’s National Institutes of Health-funded experiments have led to the development of a commercial curcumin supplement called Longvida (for which Cole and UCLA receive royalties.) He says another supplement, called Meriva, also has a lipid component and seems to be effective.

But not every expert is quite so bullish on curcumin supplements. “I think curcumin is great, but it’s not a miracle,” says Dr. David Heber, UCLA’s professor emeritus of medicine and public health, and founding director of that university’s Center for Human Nutrition.

Heber says your levels of abdominal fat, the quality of your diet and how much you exercise are a lot more important than curcumin when it comes to inflammation and your health. He also says spices in general—not just one component of turmeric—are healthy and woefully underused in the U.S. (“I joke that our favorite spices are ketchup and mustard,” he says.)

While turmeric is “among the most important spices” when it comes to potential health powers, Heber says rosemary, cinnamon, oregano and many others could make similar claims.

So what’s the turmeric takeaway? “I would absolutely encourage people to add turmeric to the foods they eat,” Heber says. A lot of research has been done on turmeric and curcumin, and there’s not much risk of overdoing it even if you eat several teaspoons a day.

Just don’t count on a miracle. “People expect these nutrients to work like drugs, but they don’t,” Heber says. On the other hand, eating turmeric and a varied assortment of spices—coupled with a healthy diet and regular exercise—will likely have very real health benefits, he says.

TIME medicine

You Asked: Is It Bad to Hold in a Sneeze?

Holding in Sneezes
Illustration by Peter Oumanski for TIME

Pulled muscles and perforated eardrums are a couple of the calamities that could befall a sneeze suppressor.

Spend some time reading medical case studies—a great way to ruin a pleasant morning, by the way—and you’ll be shocked at the unlikely ways people manage to hurt themselves. Focus on sneeze-related accidents, and you’ll notice a trend: Bad things happen when people hold in their sneezes. A fractured larynx, acute cervical pain and facial nerve injuries are just a few of the documented mishaps caused by a stifled achoo.

“I’ve seen patients with a ruptured eardrum or pulled back muscles, and you hear about cracked ribs,” says Dr. Michael Benninger, an otolaryngologist—that’s an ear, nose and throat doctor—and chairman of the Head and Neck Institute at Cleveland Clinic.

While sneezes (and the schnozes that expel them) come in many sizes, a whopper sneeze can blast air out of your nose at 500 miles per hour, Benninger says. If you redirect that force inward, your suppressed sneeze can send waves of force rippling through your head and body.

MORE: Don’t Sneeze In Space: When Astronauts Get Sick

Usually that’s not a big deal. After all, most of us have bottled a sneeze here or there without issue. But Benninger says a preexisting musculoskeletal injury or weakness, odd ear or throat physiology or some other anatomical quirk could lead to an adverse reaction to a held-in sneeze.

While such reactions are unlikely, Benninger says sneezes aren’t meant to be caged. “Sneezing probably cleanses the nose of irritants, viruses and those types of things,” he explains. He uses the word “probably” because there’s research to suggest sneezing might perform other functions, from signaling to people that you’re sick to resetting the homeostatic environment in your nose.

“I’ve read reports that people sneeze differently in different cultures—almost like a learned behavior,” he says. He adds that everything from your lung capacity to the structure of your face and nose can play a role in how forcefully you sneeze, and the potential of your sneeze to cause or exacerbate an injury.

MORE: The 7 Best Food Combinations For Weight Loss

His advice? Don’t hold in a sneeze. “If you feel one coming on and you want to stop it, rubbing your nose can help,” he says. For patients who may feel pain when sneezing—those who’ve recently undergone surgery or broken a bone—Benninger advises opening your mouth wide to minimize a sneeze’s strength. “It’s like forcing water through a pipe,” he says. “If the air can escape through your nose and mouth, that creates less pressure than forcing it through a smaller opening.”

Just make sure that when you sneeze, you’re doing it into the crook of your arm, not your hand. “We know sneezing can project smaller particles 10 to 12 feet, so it’s important to cover your mouth,” Benninger says. “But if you sneeze into your hand, everything you touch is going to be contagious.” Your clothes help absorb particles, and you probably won’t be touching much with the inside of your arm, he adds.

Gesundheit! And safe sneezing, everyone.

TIME Research

You Asked: Why Is My Stomach Growling?

Why Stomachs Growl
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Grumblings are an important part of digestion, and they may play a role in obesity and gut disorders.

You know a rumbling tummy is a sign you haven’t eaten in a while. But there’s a lot more going on down there than a quaking plea for more food.

Like street sweepers cleaning up after a parade, the gastrointestinal contractions you feel are your gut’s way of cleansing your empty stomach of left-behind food particles, bacteria overgrowth and other debris, says Dr. Toku Takahashi, a professor and gastroenterologist at the Medical College of Wisconsin.

Takahashi says the rumbling is just one phase of a larger process called the migrating motor complex (MMC), which ensures your stomach and intestines stay active and continue to clear away detritus between meals. He says a poorly functioning MMC has turned up in patients with abdominal pain, nausea, vomiting and other symptoms of indigestion or the presence of harmful microorganisms.

Aspects of your gut’s grumbling may also affect your risk for weight issues like obesity.

Feelings of hunger come from your brain, but they’re based on chemicals signals your brain receives from your gut, says Dr. Jan Tack, a professor of medicine who studies gastrointestinal disorders at Belgium’s University of Leuven. According to Tack, there’s mounting evidence that both hunger and the different phases of the MMC are triggered by a “forgotten” gut hormone called motilin.

“The hormone is ‘forgotten’ because rats and mice do not express it, so it is under-studied,” Tack explains.

Gut chemistry quickly gets complicated. But Tack says both obesity and hunger appear to be linked in some ways to your motilin levels. “We have shown that motilin-induced hunger signaling is altered in people experiencing unexplained weight loss and obesity,” he says.

Tack says a person’s motilin levels also seem to change after bariatric procedures like gastric bypass surgery. Motilin may also affect the ways you experience pleasure or a sense of reward after eating, he adds.

All of this research is very new. But manipulating motilin and the resulting MMC response may eventually emerge as a novel way to treat obesity, dyspepsia and other gut-related health issues, Tack’s research suggests.

In the meantime, one thing is certain: It’s normal and healthy to experience a grumbling stomach in between meals.

TIME Diet/Nutrition

You Asked: Can I Trust Allergy Warnings On Food Labels?

Illustration by Peter Oumanski for TIME

You can, but deciphering some of those label statements can be tricky.

When you’re trying to shop for a child with a severe peanut allergy, wishy-washy language is the last thing you want to see on a food label. So when you read warnings that begin “May contain traces of…” or “Manufactured on equipment also used for…” you may be left scratching your head.

Believe it or not, all of those “may contain” statements are voluntary under current Food and Drug Administration (FDA) regulations. While not required, food manufacturers sometimes choose to include them if there’s a chance an allergen snuck its way into your food.

“A manufacturer might use the same equipment to make different products,” explains Megan McSeveney, a press officer with the FDA. Even after cleaning this equipment, a small amount of an allergen may inadvertently end up in the next product the machine processes. In this situation, a manufacturer might include a “may contain” advisory statement, McSeveney says.

The FDA is working on new rules that would tighten regulations on this kind of cross-contamination. But for now, if you or a loved one has a severe allergy, your only safe bet is to read “may contain” as “likely contains” when it comes to label warnings, the FDA says.

That raises some important questions. For one, if “may contain” statements are voluntary, doesn’t that mean a lot of potentially contaminated food products don’t include any warnings at all? And couldn’t haphazard food manufacturers just slap on a “may contain” statement to make up for their shoddy practices?

“Companies cannot use voluntary advisory labeling in lieu of good manufacturing practices,” McSeveney says. She says the FDA can seize products with inaccurate allergen information or take other actions to ensure compliance. But, in most cases, “firms generally recall such food products from the marketplace voluntarily when they become aware of a problem,” she says.

Basically, no one is trying to hoodwink consumers—or expose someone with an allergy to a potentially harmful ingredient.

If a food product is made with any one of the eight major food allergens—milk, egg, fish, crustacean shellfish, tree nuts, wheat, peanuts and soybeans—then its label has to identify that allergen either in its ingredients list or in a “contains” statement right next to the ingredients list, McSeveney explains. Also, she says this identification has to feature the allergen’s “food source name”. That means if a product contains something like casein, which is a type of milk protein, the label has to include the word “milk” somewhere in the ingredients list or accompanying “contains” statement.

When it comes to potential allergens outside of that list of eight—gluten, for example—the FDA does not require a manufacturer to include a warning. You still may see statements like “gluten-free” on food labels. But McSeveney says that, much like “may contain” statements, any “free” from statements are voluntary. Though optional, they’re still subject to the FDAs general misbranding requirements. So rest assured, food manufacturers can’t simply lie to you without repercussions.

Though there’s certainly room for improvement in the current labeling system, up until 2006, the FDA didn’t mandate any allergy warnings. So historically speaking, the world today is a lot less uncertain for food allergy sufferers.

It might be an unsatisfying answer, but the bottom line is that life comes with an implicit “may contain” warning.

TIME Exercise/Fitness

You Asked: Is It Healthy to Sweat A Lot?

You Asked Healthy Sweat
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If you’re hot, perspiration is normal—even lots of it. But there are other times when excessive sweating could be cause for concern.

Here’s the tricky thing about using sweat as a barometer for health: “A lot of it comes down to biological variation,” says Dr. Craig Crandall, a professor of internal medicine at the University of Texas Southwestern Medical Center.

Crandall says if you examined two people—same height, sex and build—one might produce twice the volume of perspiration as the other. “It could just be one person has more sweat glands,” he explains. “Everybody’s baseline is different, so it’s hard to say what amount of sweat is ‘healthy’.”

Still, patterns emerge when you look at big groups of people.

A 2010 study from Japan examined how fit men and women sweat in response to exercise, and compared their sweating rates to those of unfit people. Fit people not only perspire more, but they also start sweating sooner during exercise, says study coauthor Dr. Yoshimitsu Inoue of Osaka International University. Men also tend to sweat more than women, Inoue says.

Crandall says the differences between fit and unfit people has to do with each person’s capacity for heat generation. “A high fitness level allows you to exercise at a higher workload, which generates more heat, which in turn leads to more sweat,” he explains.

He says men tend to sweat more than women for the same reason overweight or obese adults often sweat more than thin people: Their bodies are larger, which leads to greater heat generation during activity.

Crandall’s own research has found people sweat more after spending time in hot climates. “An athlete training here in Texas versus someone up in Montana may sweat differently in the same conditions,” he says. “Their bodies adapt in response to hot or humid environments.”

So sweat is complicated. But most of the research suggests perspiring in response to heat or exercise—whether you sweat a little or a lot—doesn’t mean much about your health.

Of course, there are other forms of sweat that have nothing to do with heat regulation.

People sweat when they’re nervous, and Crandall says nervous sweat tends to come from different glands than exercise- or heat-induced sweat. “The sweat glands that are sensitive to emotions are mostly under the arms, in the palms, and in the soles of the feet,” he says. While that’s unfortunate for nervous sweaters, there’s no evidence that people who sweat a lot due to worry are less healthy than those who aren’t as emotionally sweaty.

There’s also a condition called hyperhidrosis, which is excessive sweating either all over your body or in one particular area, such as your palms or pits. Excessive means up to four or five times what most people would sweat, says Dr. Adam Friedman, a dermatologist and residency program director at the George Washington School of Medicine and Health Sciences.

While the cause of this pernicious perspiration is often not identifiable, it can stem from an infection or illness, certain medications or an underlying endocrine condition like thyroid disease, Friedman says. Because of these links to health concerns, he says people who sweat all the time, day and night, should speak with a doctor.

Regardless of how much you perspire, exactly what you’re perspiring doesn’t vary much from person to person. Crandall says, “Sweat is basically water, sodium chloride, and potassium”—all of which you have to replenish after sweating heavily, he says.

And no, despite what you may have heard from the detox circuit, sweating does not rid your body of “toxins”. “It’s not like parts of the junk food you ate are going to escape through your sweat,” Crandall says. “There’s just no evidence of that.”

TIME public health

You Asked: Is My Air Conditioner Killing Me?

You Asked Air Conditioner Killing Me
Illustration by Peter Oumanski for TIME

It can be unhealthy for you—and it’s certainly bad for the planet. It could also save your life.

In the summer, many of us can’t bear to live without it, but even so, cool air is a modern luxury that sometimes seems to freak people out.

“We had forms of heating for a very long time before we ever had air conditioning,” says Dr. Stan Cox, senior scientist at The Land Institute in Salina, Kansas, and author of Losing Our Cool: Uncomfortable Truths About Our Air-Conditioned World. Cox points out that as recently as the 1960s, only 12 percent of Americans had some kind of AC in their homes. While heat was an absolute necessity for people to live in cold climates, Cox says, air conditioning is more of a newcomer on the climate-controlled front.

And research suggests that a little freaking out is warranted. “If you have a badly maintained or badly designed AC system, whether it’s in your home or office or vehicle, it can become contaminated and potentially harmful,” says Dr. Mark Mendell, an epidemiologist with the California Department of Public Health.

Mendell studied the health effects of air conditioning systems while with the U.S. Department of Energy’s Lawrence Berkeley National Laboratory. He says worsening asthma problems and allergies are two health issues that can stem from contaminated AC units. He also mentions an ominous-sounding phenomenon: sick building syndrome.

“We started seeing it in the 70s and 80s,” Mendell says. “People in office buildings started saying the building was making them sick.”

He says sick building syndrome was associated with a range of seemingly unrelated symptoms: nasal congestion, breathing problems, headaches, fatigue and irritated skin. His own research has linked AC systems in office buildings to many of those same symptoms.

“The most likely explanation is that there may be some microorganisms growing in the system that may have some subtle effect on certain people,” Mendell says. “But it’s not clear how many people are sensitive to this or how big of a problem it is.”

Unlike heating systems, the process of cooling hot air creates a lot of moisture and condensation, which must be channeled away, Mendell explains. If your AC system does a bad job of this, whether due to poor maintenance, damage or shoddy design, it can become a breeding ground for bacteria and fungi. To protect yourself, he says, your best defense is a well-maintained and routinely serviced AC unit. (HVAC repairmen, you owe this guy!)

But Mendell is also quick to point out that AC has been firmly linked to many health benefits. “Outdoor air pollution is common in urban environments, and especially in heavy traffic,” he says as just one example. “AC filters out the particles in outdoor pollutants.”

Exposure to airborne pollution particles can raise your risk for hospital admissions and premature death due to cardiovascular issues, says Dr. Michelle Bell, a professor of environmental health at Yale University. Bell’s research found the use of well-maintained AC use lowered a person’s risk for these health complications. “Use of central air conditioning causes less outdoor air pollution to penetrate indoors compared to open windows,” she says.

Both Bell and Mendell also say that during intense heat waves, AC saves lives.

If this seesawing between AC’s benefits and risks feels disorienting, you’re not alone. “Anyone who does research on these systems will admit there’s still a lot of things we don’t know,” Mendell says.

What isn’t in doubt, though, is air conditioning’s very real and harmful impact on the planet.

“The headline issue is its contribution to greenhouse warming,” says Cox, the Land Institute environmental researcher. Indoor heating has long been a bigger contributor than AC to the accumulation of harmful greenhouse gasses, Cox says. But the U.S. population’s southward shift has allowed AC to catch up—and maybe draw even.

Despite his concern for the planet, Cox says that AC can be life saving and beneficial. But he takes issue with what he calls our “lavish” use of any climate control conveniences. Setting our thermostats a bit higher in summer and a little lower in winter would benefit the environment without affecting anyone’s health, he says.

In fact, a little thermal discomfort could be good for you. People tend to eat more and gain more weight when the temperature is perfectly cozy, Cox says. “When we’re a little cold or a little warm, our metabolism runs faster,” he says. Research backs him up: One recent study found exposure to cold temps—enough to make you shiver—may increase your body’s stores of healthy, energy-burning brown fat.

Cox adds that your body can adapt to a range of temperatures. (This is why you break out the shorts and T-shirts on that first 65-degree spring day, but the same thermostat reading in autumn sends you hunting for jeans and sweaters.) So if you can cut out the heat or cold for a week or two, your body will often acclimate to temperatures you found unpleasant at first—and easing up a bit on the AC will make the planet thank you, too.

TIME Mental Health/Psychology

You Asked: Do I Worry Too Much?

You Asked Do I Worry Too Much
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Frequent fretting is unproductive and not so hot for your health.

As human beings, our ability to predict trouble—and outwit it—is one of those cerebral superpowers that set us apart from birds and beasts. But nonstop worrying can be crippling to your life and your immune system.

“Just having a thought about some potential bad thing that might happen—everyone has those,” says Dr. Michelle Newman, director of the Laboratory for Anxiety and Depression Research at Pennsylvania State University. “But if you have difficulty stopping the worry once it starts, that’s one of the ways we define what’s called pathological worry.”

Newman, who is also editor of the journal Behavior Therapy, cites more characteristics of out-of-control worrying, like fixating on things over which you have no control—or which have a low probability of happening—and “catastrophizing” them. Worrying about a loved one who’s driving and picturing the horrible ramifications of an accident is one example; imagining a string of events that might lead to your losing your job and your home is another.

Anxiety is a related feeling that often goes hand in hand with worrying. While it can be a little tricky to separate the two, Newman says the technical difference is that worrying is “verbal-linguistic” while anxiety is “physical.” If you feel tense or on edge while thinking about your job security or your child’s long car trip, you’re experiencing both worry and anxiety. Feel those emotions “more days than not” for a period of six months, and you meet the American Psychiatric Association’s criteria for a diagnosis of generalized anxiety disorder, or GAD. Basically, you’re a chronic worrier.

“I like to say that chronic worry is a process looking for content,” Newman says. “You’ve gotten into the habit of looking for something to be concerned about, and you always find it.”

That’s bad news for several reasons. First and foremost, incessant worrying and anxiety can increase your blood pressure and heart rate and has been linked to an elevated risk for cardiovascular disease. “Anxiety can also over-activate your immune system,” says Dr. Wesley Moons, formerly of the University of California, Davis, and now CEO of his own consulting firm, Moons Analytics.

While at UC Davis, Moons and his graduate student Grant Shields found that people who reacted to stressful situations with anger experienced a smaller immune system response than those who reacted with anxiety. Shields says the sorts of immune system responses his research linked to anxiety could hurt the body’s ability to fight off infection or disease and have been tentatively linked to higher mortality rates.

“That’s not to say getting angry is a healthy reaction to stress,” Moons adds. “But in terms of your immune system, anxiety appears to trigger some different and potentially more detrimental responses.”

But isn’t there a benefit to lots of worrying? After all, if your mind is tackling contingencies and potential threats, you can act now to prevent them—right?

Unfortunately, Newman refutes this idea. “Mostly worrying becomes a process unto itself that doesn’t lead to problem solving or helping you in any way,” she says. If you’re worrying about something, she says, you’re not taking steps to address the source of your worry, if that’s even possible.

When you boil it down, worry is really a failure to live in the moment, Newman says. Activities that attempt to anchor your mind to the present—including yoga and meditation—may help combat incessant worrying. Exercise, massage and other things that alleviate physical tension are also helpful, she says.

Another great way to reign in your worrying is to set aside a specific time and place for it. Select a spot you can get to easily every day, but that isn’t a place where you normally spend time, Newman advises. (A quiet bench in your backyard, maybe, or a chair in your guest room.) Your goal is to give yourself 20 or 30 minutes a day in that space, devoted only to worrying. “The rest of the day, you tell yourself you aren’t going to worry because you will at that time and place,” Newman explains. “The idea is that by isolating your worry, you can control it.”

She says that focusing on a favorite relaxing setting—your “happy place”—also has proven worry-reducing benefits. “Close your eyes,” she says. “Try to vividly picture that place—the sights and smells and sounds you would feel and hear.” Hopefully the place that you see is worry-free.

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