TIME Diet/Nutrition

You Asked: What’s the Healthiest Sweetener?

Illustration by Peter Oumanski for TIME

Why sweet and good-for-you might not go together

You’ve heard sugar is bad news. But what about all those low-cal or no-cal substitutes? And organic honey! That has to be healthier, right?

“Honey, table sugar—doesn’t matter. It’s all sucrose, and your body metabolizes it the same way,” says Dr. Robert Lustig, a pediatric endocrinologist at the University of California, San Francisco. Lustig is also board president of the Institute for Responsible Nutrition, and presenter of “Sugar: The Bitter Truth”—a much talked about YouTube lecture that lays out the perils of the sweet stuff.

Apart from its high calorie content, which contributes to weight gain and obesity, sugar messes with your body’s insulin responses, Lustig says. Heart disease, diabetes and fatty liver disease have all been linked to the types of insulin issues sugar provokes.

“Sugar also binds to proteins in your body and causes damage,” he says—the same kind that browns fruit left out on your kitchen countertop. “We’re all browning. That’s part of aging,” Lustig explains. “But sugar causes you to brown seven times faster.”

There’s more to say on the subject of sugar and your health, but the bottom line is that too much sugar is bad for you, and most Americans consume way more than they should. “Your liver can process roughly six to nine teaspoons a day without significant issue,” Lustig says. “The average American consumes 19.5 teaspoons a day.” And while honey may contain antioxidants or compounds that, on their own, may offer some benefits, “The sucrose in honey is still sucrose,” Lustig adds.

Unfortunately, when it comes to artificial sweeteners and other sugar alternatives—from stevia to sucralose—the health picture grows foggier, not clearer. “Some people believe that, because some artificial sweeteners have no calories, they have no consequences,” says Dr. Yanina Pepino, research assistant professor in medicine at Washington University in St. Louis. “But we know that’s not true.”

Pepino’s research has demonstrated that sweet tastes—even those produced by non-caloric sweeteners—have the power to ramp up your body’s insulin responses. She says there’s also data suggesting non-caloric sweeteners contribute to the development of metabolic disorders and type 2 diabetes.

MORE: Should I Drink Diet Soda?

More new research has hinted that artificial sweeteners may mess with your gut’s microbes, the tiny organisms that live in your digestive system and help manage the ways your body breaks down and processes the stuff you eat. Like opening Pandora’s box, Pepino says any changes to the gut’s microbiota may lead to widespread negative health consequences.

“When it comes to sugar substitutes, we just don’t know enough,” she says—a sentiment Lustig repeats over and over again. And not knowing makes choosing between sugar and sugar alternatives a thorny proposition.

While some new sweeteners may claim to be healthier than others, the fact is they’re simply newer, so there’s not as much known about them, Lustig says.

In the end, both he and Pepino agree there’s only one right answer if you’re watching out for your health: Limit the amount of sweet stuff in your diet.

“I know people won’t like that answer, but that’s the only one I can give,” Pepino says. “There’s just no way to say one is better than another without a lot more data.”

TIME Research

You Asked: What’s the Best Way to Whiten My Teeth?

Illustration by Peter Oumanski for TIME

Pearly whites are just a dentist’s visit away, but they’ll cost you

Like a shiny new watch or a sparkling personality, white teeth are an ornamentation. Both men and women are attracted to a bright white smile, concludes a study in the journal PLOS One. Additional research has shown job applicants with white teeth are more likely to be hired than yellow-toothed applicants.

From whitening toothpastes and over-the-counter strips to dental office procedures, all tooth-whitening measures employ hydrogen peroxide to clean away stains. “The only differences are the concentrations of hydrogen peroxide employed and how they’re held against your teeth,” explains Dr. Matt Messina, an American Dental Association spokesperson who practices dentistry in Cleveland.

Of course, cost is also a factor. Starting with the least-potent (but least-expensive) whitener, Messina says toothpastes contain 1% to 1.5% concentrations of hydrogen peroxide. “That’s adequate to clean surface stains,” he says, “but it won’t penetrate your tooth enamel.” The enamel tends to hold the deepest, hardest-to-remove blemishes—that patina of black coffee or red wine that gradually accumulates on your smile like vehicle pollution on the sides of old brick buildings.

So if your teeth are seriously stained, a whitening toothpaste alone won’t get the job done—no matter how hard you brush. (In fact, brushing forcefully can damage your gums and is never advisable, Messina warns.)

Over-the-counter gels or strips are the next level up on the hydrogen-peroxide/price spectrum. “They’re usually in the 6% to 10% range, ” Messina says. At these concentrations, the hydrogen peroxide can penetrate microscopic holes and fissures in your enamel to bubble away stains.

While over-the-counter options can be very effective, Messina says the key is to apply them evenly and keep them on as long as directed. “I usually recommend the strips over the gels because they stay in place,” he explains. If the strips or gel are applied incorrectly, your teeth could look unevenly white. Gum irritation is also possible, he says.

But remember this important caveat: whitening agents do not work on caps, crowns or fillings. If you’ve had some dental work done, you should speak with your dentist before you whiten your teeth to be sure the results will look uniform, Messina says.

Another step up in both cost and potency is dentist supplied “tray-and-gel systems,” which contain hydrogen peroxide in the 10% to 15% range and can cost several hundred dollars. After custom fitting your mouth with a mold, your dentist supplies a take home tray and whitening gel for you to use at home. “The custom tray ensures the gel is evenly applied, and it can produce some pretty impressive results,” Messina says.

The final and most expensive option is settling into your dentist’s chair for a series of 10- to 15-minute whitening treatments. With hydrogen peroxide concentrations as high as 35%, these treatments can make your smile a dozen shades brighter, Messina says. They can also run you more than $1,000. “Whitening is a strictly cosmetic procedure, so it’s almost never covered by insurance,” Messina says.

So how white should you go? That’s really a personal preference thing, Messina says. While some people want their teeth as white as possible, the same PLOS One study mentioned above found that people with “natural” looking teeth scored just as highly in terms of attractiveness when compared to people with ultra-bright white smiles.

It’s also possible to over-whiten your teeth, Messina says. “If you whiten excessively, the tooth enamel can actually become translucent, which can make the teeth look blue or gray.” That’s not harmful in the long-term, but blue teeth isn’t a hot look.

While über-white teeth may not be any healthier than stained chompers, Messina says he thinks there are dental health benefits associated with a whiter smile. “I’ve found people who’ve had their teeth whitened are better at brushing and flossing,” he says. “When you’re proud of something, you take better care it.”

Read next: You Asked: Is Sleeping In a Cold Room Better For You?

TIME Research

You Asked: What Is My Poo Telling Me?

you-asked-poop
Illustration by Peter Oumanski for TIME

Your excrement is illuminating

Some say you are what you eat. But really, you are what you poop. “Not only does stool tell you about the health of your diet, but it shows you how your body’s digestive system is handling the foods you eat,” says Dr. Anish Sheth, a Princeton-based gastroenterologist and author of What’s Your Poo Telling You?

From hemorrhoids to cancer, diseases grave and small often show up first in your feces, Sheth says. And in recent years, health experts have learned your excrement also contains a wealth of information about your microbiome, the world of microscopic organisms that live and support your body’s many internal systems.

Put simply, your poop is a window to your health—even if you don’t consider the view all that appealing.

The first thing to consider when assessing your stool (a practice Dr. Sheth heartily advocates) is consistency, both in terms of physical attributes and regularity. “The ideal stool,” Dr. Sheth says, “has been described as a single soft piece.” You’re looking for something log-ish but not too firm, he continues. Imagine dispensing soft serve ice cream into your toilet, and you’ll have the general, somewhat less delicious idea.

This type of stool indicates you’re getting plenty of water and fiber in your diet. An absence of either can produce firmer, broken-up, difficult-to-expel feces or constipation, Sheth says. How hard you have to push is also important, he adds. Ideally, you should “evacuate” your waste with almost zero effort and feel as though you’ve fully emptied yourself.

Of course, everyone has the occasional bout of diarrhea or too-firm poo. But Sheth says neither should worry you much if it happens just once or twice before you’re back to normal. If a week passes without you passing healthy-looking stool, you should speak with a doctor. Even if you’re taking a number-two every day, hard or broken-apart poop is a sign that your diet is probably too low in fiber or water, which can lead to all sorts of gastrointestinal (GI) tract issues, Sheth says.

The color of your feces is also important. If it appears black or tarry, that may be evidence of blood. “The darker the stool, the higher up in your GI tract the blood is likely coming from,” Sheth says. He explains that blood emanating from ulcers or stomach problems will darken as it passes through your digestive system.

If you see maroon or dark red hues or streaks in your poop, that could mean inflammation, colitis, or certain intestinal cancers, Sheth explains. Bright red blood often indicates hemorrhoids or problems localized very near your anus.

Even the buoyancy of your bowel movements can reveal concerns. If your poop usually floats, that may signal an issue with your body’s ability to absorb fat, which in turn might mean your pancreas is having problems, Sheth says. Some particularly bad odors could also be red flags for health issues, although you probably wouldn’t know them if you smelled them. “Some doctors can identify certain GI diseases just by the distinct smell, although people who don’t diagnose them all the time wouldn’t be able to,” Sheth explains.

To keep your poop and your health in top form, Sheth recommends a diet than includes, again, plenty of fiber. “The average American gets about nine grams of fiber a day, when you need 25,” he says. He recommends lots of whole grains, fruits, vegetables, legumes and seeds like flax or chia. “Throw those in a daily smoothie,” he suggests. “And look before you flush!”

TIME

You Asked: Should I Go Paleo?

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Illustration by Peter Oumanski for TIME

It’s more than a diet; it’s a way of life. Just ask a Paleo person.

The Paleo premise seems tantalizingly sensical: For hundreds of thousands of years, human beings ate and lived in ways that bear little resemblance to our modern modes of existence. It stands to reason that our bodies and minds haven’t had time to adapt, and that the unhappy consequences are stress, obesity, disease and a general feeling that, well, our primitive ways were probably preferable.

The solution, according to Paleo proponents, is a return to our roots. From aligning your sleep schedule with the rise and fall of the sun to exercising like your ancient ancestors—barefoot running, climbing, lifting heavy stuff—there are countless ways to channel your Paleolithic predecessors. And for most people, “going Paleo” starts in the kitchen.

Eating a Paleo diet involves consuming lots of lean meat, as well as eggs, fruits, some nuts, seeds and vegetables—basically, the kinds of foods humans were forced to subsist on for most of history. Dairy, grains, beans and all other foodstuffs unavailable in cave-dwelling days are verboten. So are foods with added hormones and artificial additives like processed sugars.

MORE: What’s Right and Wrong About Eating Like a Caveman

Proponents of the Paleo diet claim miraculous gains in energy, mental acuity, physical strength and general health. But naysayers point out the diet is expensive, difficult and probably not sustainable. (There are 7 billion people on Earth, and there’s only so much meat to go around.)

But what does the research show? Several studies have compared Paleo-style diets to the average American diet and found, unsurprisingly, that Paleo pounds our standard fare. Among the Paleo crowd, weight fell off faster, body composition improved and both blood pressure and blood sugar scores tacked toward healthier numbers, found one paper from the University of California San Francisco.

Another long-term study from Sweden saw similar health gains after comparing a meat-centric Paleo plan to a carb-heavy Nordic diet. In particular, triglycerides—a type of blood fat that raises your risk for heart disease—plummeted among the Paleo dieters, the Swedish study shows.

MORE: Can the Paleo Diet Help You Lose Weight?

But not so fast. “I do not believe there is anything magical about the Paleolithic diet,” says Caroline Mellberg, a doctoral researcher at Sweden’s Umeå University and coauthor of the Swedish study, in addition to several others that have looked into the viability of a Paleo-style diet. While she doesn’t dispute the diet’s benefits, she says her team’s findings aren’t surprising when you consider all the foods you have to ditch when you stick to a Paleo-inspired menu.

“Most unhealthy food items are excluded, and no empty calories are allowed,” she explains. Take out the crap from any diet, and she says you’d likely see many or all of the same health benefits.

MORE: How To Be A Modern-Day Caveman

Other nutrition experts say there just aren’t any research-backed reasons to drop dairy, legumes and grains, and that doing so might have unintended health consequences. “These foods provide many nutrients that have been shown over and over again to be beneficial for optimal health,” says Stephanie Maxson, senior clinical dietitian at the University of Texas MD Anderson Cancer Center.

Maxson is quick to add that she thinks Paleo diets can be healthy. Her point—and one that many others have also argued—is that the extremes Paleo diets prescribe are unnecessary. “Dieting is tough,” Maxson says. And when it comes to a meal plan that restricts you to a slim cluster of food groups, your chances of staying with it are just as small, she says.

If you’re in the market for a healthy diet, you might want to consider Paleo for its impressive health benefits—but only if you’re also ready to take a caveman club to most of your current kitchen, too.

Read Next: Are All Calories Created Equal?

TIME

You Asked: Is Sleeping In a Cold Room Better For You?

Illustration by Peter Oumanski for TIME

Here's the sweetest spot on the thermostat

Ask any insomniac about the perils of a hot pillow: When you’re trying to sleep, your brain loves the cold. Wearing a cooling cap helped insomniacs snooze almost as well as people without sleep problems, found a study from the University of Pittsburgh School of Medicine, and there’s also some evidence that yawning helps your brain offload heat before bedtime.

In fact, there’s lots of evidence for the cooler camp. A drop in your core temperature triggers your body’s “let’s hit the sack” systems, shows research from the Center for Chronobiology in Switzerland (and a lot of other places.) Some new research from the National Institutes of Health also suggests that sleeping in a cool room could have some calorie-burning health benefits. Healthy men who spent a month sleeping in a cool (but not cold) 66-degree room increased their stores of metabolically active brown fat, says Dr. Francesco Celi, chair of Virginia Commonwealth University’s division of endocrinology and metabolism. “Brown fat” may not sound very desirable, but it actually helps your body burn calories and dispose of excess blood sugar, he explains.

“We found that even a small reduction in bedroom temperature affects metabolism,” Celi says.

So if you want a healthy night’s sleep, crank down the thermostat, right? Unfortunately, it may not be that simple—when it comes to all of your below-the-neck parts, things aren’t so straightforward.

In Celi’s brown fat experiment, the men slept under thin sheets. What if you’re the type who likes a cozy down comforter? “Sorry, that won’t work,” Celi says, adding that some evidence points to shivering as the mechanism that brings on the increase in brown fat his team observed. His experiment didn’t keep tabs on sleep quality. So while the cold may be good for your metabolism and brown fat stores, you may be paying for those benefits with a night of fitful sleep.

That possibility is supported by research from Dr. Eus van Someren and colleagues at the Netherlands Institute for Neuroscience. While a dip in core temperature before bedtime flips on your brain and body’s “time for bed” switches and helps you fall asleep, Someren’s research shows that keeping your skin temperature “perfectly comfortable” is important when it comes to maintaining deep, restful slumber.

Your level of “perfect comfort” is quite individual. But if you’re cold enough to be shivering, you’re not sleeping deeply, Someren says. His research shows that older adults in particular may benefit from warmer skin temperatures during sleep. In fact, both his work and more research from France suggest skin temps in the range of 90 degrees (!) may be optimal.

If that sounds nuts to you, consider the fact that thin pajamas, plus a sheet and blanket, could crank up your skin temperature to that 90-degree range—even if your room of slumber is only 65 degrees, Someren says. On the other hand, if your bedroom is too chilly or your blankets aren’t thick enough, blood vessels in your skin can narrow, locking in heat and upping your core temperature to a point that your sleep is disturbed, he explains.

Add in a sleeping partner, and things get even more complex; while you may yearn for a heavy down comforter, your spouse might prefer a thin sheet. “Temperature regulation is a tricky thing,” Someren says.

That’s a lot of bedroom science, but here’s the bottom line: keeping your head nice and cool is conducive to good sleep. To achieve that, set your thermostat somewhere around 65 degrees, research suggests. And layer up until you feel the Sandman creep closer.

TIME Mental Health/Psychology

You Asked: Does Laughing Have Real Health Benefits?

Illustration by Peter Oumanski for TIME

Your body could use a belly laugh

It may not be the best medicine. But laughter’s great for you, and it may even compare to a proper diet and exercise when it comes to keeping you healthy and disease free.

That’s according to Dr. Lee Berk, an associate professor at Loma Linda University in California who has spent nearly three decades studying the ways the aftershocks of a good laugh ripple through your brain and body.

Berk says your mind, hormone system and immune system are constantly communicating with one another in ways that impact everything from your mood to your ability to fend off sickness and disease. Take grief: “Grief induces stress hormones, which suppress your immune function, which can lead to sickness,” he says. Hardly a week goes by without new research tying stress to another major ailment.

Why mention stress? “Because laughter appears to cause all the reciprocal, or opposite, effects of stress,” Berk explains. He says laughter shuts down the release of stress hormones like cortisol. It also triggers the production of feel-good neurochemicals like dopamine, which have all kinds of calming, anti-anxiety benefits. Think of laughter as the yin to stress’s yang.

Thanks largely to these stress-quashing powers, laughter has been linked to health benefits ranging from lower levels of inflammation to improved blood flow, Berk says. Some research from Western Kentucky University has also tied a good chuckle to greater numbers and activity of “killer cells,” which your immune system deploys to attack disease. “Many of these same things also happen when you sleep right, eat right, and exercise,” Berk says, which is why he lumps laughter in with more traditional healthy lifestyle activities.

Berk has even shown that laughter causes a change in the way your brain’s many neurons communicate with one another. Specifically, laughter seems to induce “gamma” frequencies—the type of brain waves observed among experienced meditators. These gamma waves improve the “synchronization” of your neuronal activity, which bolsters recall and memory, Berk says.

How does laughter accomplish all this? That’s where things get murky, says Dr. Robert Provine, a neuroscientist at the University of Maryland, Baltimore County and author of Curious Behavior: Yawning, Laughing, Hiccupping, and Beyond.

Provine calls himself a “reserved optimist” when it comes to laughter’s health-bolstering properties. “One of the challenges of studying laughter is that there are so many things that trigger it,” Provine explains. For example, you’re 30 times more likely to laugh around other people than when you are by yourself, he says. Social relationships and companionship have been tied to numerous health benefits. And so the social component of laughter may play a big part in its healthful attributes, Provine adds.

Here’s why that matters: If you’re going to tell people they should laugh to improve their health, there may be a big difference between guffawing on your own without provocation, watching a funny YouTube clip or meeting up with friends who make you laugh, Provine says.

“That doesn’t mean the benefits aren’t real,” he adds. “But it may not be accurate to credit laughter alone with all these superpowers.”

But even for researchers like Provine who aren’t ready—at least not yet—to coronate laughter as a panacea, he doesn’t dispute the benefits associated with a hearty har har. He only questions science’s current understanding of the underlying mechanisms.

“When we laugh, we’re in a happy place,” he says. “That’s always a good thing.”

Read next: Is It Good Or Bad To Take A Nap?

TIME Exercise/Fitness

You Asked: Is Running on a Treadmill as Good as Running Outside?

runnig on a treadmill or outside
Illustration by Peter Oumanski for TIME

Nope—but it can come pretty close with one small tweak

To dedicated runners, running outside gets all the glory. Some purists even eschew headphones (and shoes!). But when talking about whether treadmill running is “the same” as running outdoors, it helps to pinpoint what sort of sameness matters to you.

In terms of the mechanics of your stride, there’s not much difference between running on a treadmill and running on ground, says Dr. Irene Davis, a professor of physical medicine and rehabilitation at Harvard Medical School who has studied the differences between treadmill and over-ground running. “While it feels much different to you, the leg motions and the forces experienced by your body are very similar between these conditions,” Davis says.

But when it comes to your risk for injuries, there may be an important difference. “Most running injuries are overloading injuries that involve muscle, cartilage, bone or tendons wearing down over time,” Davis explains. While there isn’t a lot of good research on this, Davis says those types of injuries probably occur more frequently when you repeat the exact same running motion thousands and thousands of times—as you would on a treadmill or a flat, consistent stretch of pavement.

“You strike the ground 1,000 times per foot, per mile,” she says. And if you’re running on a treadmill or a flat, hard surface, the redundancy of your motion increases your risk for these overuse injuries.

On the other hand, Davis suspects that changing up your stride has a beneficial effect on your injury risk. The more you move in response to curbs, corners, hills or leashed pets, the less likely you are to overburden the same muscle or tendon. Running courses that include lots of slopes, speed changes, and impediments—especially nature trails—are probably safest when it comes to your risk for wear and tear, she hypothesizes.

But what about the effort involved in running outdoors as opposed to on a treadmill? The big factor here is “air resistance,” which you’ll encounter more of outdoors than you will inside, finds a much-cited study from the University of Brighton in the UK. But there’s an easy fix for treadmill runners: By raising the grade of your belt very slightly—just 1% of added incline—you’ll mimic the effects of outdoor air resistance, the study authors conclude.

There may also be a psychological factor to the debate. Lots of research has found that time spent outside, especially in green spaces like woods or parks, offers benefits ranging from improved mood and energy levels to better sleep. And another UK study—this one from the universities of Exeter and Essex—found that runners who ran outdoors in natural environments reported greater feelings of revitalization and wellbeing, and decreases in tension, confusion, anger and depression. (Just don’t forget sun protection.)

All things considered, running outdoors and on trails makes the most sense for maximizing the benefits of running. But if the weather’s bad or a treadmill is your only option, don’t sweat it. It may be an inferior alternative, but only slightly so.

TIME Diet/Nutrition

You Asked: Is Eating Dessert Really That Bad For Me?

Illustration by Peter Oumanski for TIME

Mixed news on the dessert front, but there's a cherry on top

If you’re sampling sweets every night—and you aren’t super disciplined during the day—then yes, dessert is that bad for you.

Of course, there are different types of desserts. Dark chocolate, nuts, fruit and mishmashes of those ingredients generally aren’t a problem. Knock yourself out. But we’re talking about the oldies and goodies here: Cake. Ice Cream. Cookies.

“Combinations of sugar, white flour, butter and trans fat are diabetes on a plate,” says Dr. Walter Willett, chair of the department of nutrition at the Harvard School of Public Health. Studies have linked these ingredients to obesity and increased rates of type 2 diabetes. So if you’re eating dessert most nights, you’re asking for trouble, Willett says.

Of course, when it comes to anything diet related, there’s always a gray area. And for dessert lovers, that gray area exists if you’re very active during the day and you generally eat a diet low in added sugars, says Dr. Rachel Johnson, a professor of nutrition at the University of Vermont and chair of the American Heart Association’s (AHA) nutrition committee.

It’s important to clarify what Johnson means by “added sugars.” These are the sugars that don’t exist naturally in the foods you consume. For example, most dairy products and fruits contain sugar in the form of fructose and lactose. But when you buy a fruity drink or flavored yogurt, those natural sugars are supplemented with more of the sweet stuff. A lot more, in most cases. And those “added” sugars are the ones studies have tied to elevated blood pressure, out-of-control inflammation, abnormal blood lipids and heart disease, Johnson says.

The AHA says women should eat no more than six teaspoons—or about 100-calories’ worth—of added sugars per day. For men, that jumps to nine teaspoons or 150 calories, Johnson says. Most dessert foods contain that much sugar, or a whole lot more. And unless you’re making all of your own meals from scratch, you’re probably hitting or vastly exceeding that daily sugar allotment way before you reach for your evening ice cream. “Everything from ketchup and salad dressing to soups and bread will contain added sugars,” she says.

Johnson says super-active adults can eat a little more sugar without worrying. But even if you’re an exercise fiend, sugary dessert calories are still “empty” calories—meaning they’re not doing your health any favors even if they’re not hurting you.

Ok, you get it. Desserts aren’t good for you. (Surprise!) But if you love them and look forward to them all day, go ahead and have some, says Nyree Dardarian, director of the Center for Integrated Nutrition and Performance Coordination at Drexel University. “When you put rules and restrictions on something, you’re only going to want it more,” she says, which might be why recommendations to eat dessert just once a week or on special occasions often fail.

Instead of denying yourself the object of your affection—and thereby stoking its appeal—focus on portion control and breaking bad dessert habits, Dardarian says. You may be used to slicing pie generously or inhaling four or five cookies. But you’d probably feel just as satisfied having much less. “Don’t get in the habit of always having the same dessert,” or the same portion, she says. And don’t just eat out of habit: you may find there are nights when you’re not that interested in dessert.

And make it as cumbersome on yourself as possible to grab seconds, Dardarian recommends. If you put the cookies or cake back in its package and into the cupboard or fridge before you start eating, you’re a lot less likely to go back for more.

Johnson also recommends making your own desserts. The stuff you buy at the store is typically overloaded with sweet stuff (and chemicals.) But if you bake your own treats at home, you can substitute healthier oils, remove much of the sugar and toss in healthy additions like nuts.

“There are ways to satisfy your dessert craving in healthier ways,” Johnson says, “if you’re thoughtful about it and willing to put in a little effort.”

TIME Mental Health/Psychology

You Asked: Is Scaring Myself Healthy?

Illustration by Peter Oumanski for TIME

A little boo is good for you

For most people, a scare provides more treats than tricks.

When Michael Myers pops up behind Jamie Lee Curtis, your heart beats faster, your pupils dilate and your muscles tense in preparation for action, says Dr. Margee Kerr, a sociologist who studies fear and the ways it haunts our bodies and minds. This happens because fear floods your brain with “a powerful chemical punch” of fight-or-flight hormones and neurotransmitters, she says. Those include endorphins and dopamine—feel-good chemicals that dull pain, excite your mood and create an incredible natural high similar to falling in love (or doing some illicit drugs).

“Even though you knew you were never really in danger, you still feel a sense of euphoria after making it through a frightening event,” says Kerr, who also works with the design team of a haunted house in Pittsburgh called ScareHouse.

When you’re freaked out, your body also starts pumping out a bonding chemical called oxytocin—the same hormone that mothers produce during childbirth. This can make a frightful experience a fantastic way to solidify friendships and other social relationships. “Watch people walking out of a haunted house, and you’ll see lots of smiles and high fives,” Kerr says. Strong social connections have been linked to dozens of health benefits, including a longer life. And friends who are scared together, stay together, she adds. (Lovers, too, so pick the scary movie for a great date.)

There’s even some evidence that experiencing fear can bolster your ability to handle high-stress situations. Whether you’re watching a freaky flick or speaking in public, managing a knee-knocking ordeal builds self-assurance and acclimates your body to high-arousal states. “You become more comfortable with the physical experience of fear, and so you’re better able to work through it during tense situations,” she explains.

In fact, Kerr and colleagues at the University of Pittsburgh are hopeful that exposure to minor sources of fear—like seeing a horror film—could help those suffering from post traumatic stress disorder (PTSD) re-learn how to manage their fear responses in healthy ways. It’s just a hypothesis right now, but if a PTSD sufferer can engage with benign scary experiences and stay in control, he or she may become more comfortable with the deeper sources of their anxieties, she says.

But it’s important to note that not all people respond to freaky situations in healthy ways. “Everyone has a different tolerance level when it comes to fear,” Kerr says. What might be energizing or thrilling to one person might be debilitating to another. “Some people just shut down or are traumatized by their fear,” she adds. This can lead to nightmares, a prolonged inability to sleep, or unhealthy levels of anxiety.

“I worry when I see people being dragged into haunted houses or scary movies,” Kerr says. “They go along because of social pressure, but the type of fear they might experience can create some of these very negative consequences.”

Kerr also says children don’t respond to frightening situations in the healthy ways many adults do. “Kids who are younger than six or seven can’t separate real from make-believe, and seeing something frightening can be really traumatizing,” she explains.

But for many adults, a little scare now and then is a good, healthy way to experience some excitement. It’s just not for everyone. “People know what they enjoy and what they don’t when it comes to fear,” Kerr says. “What you find fun or thrilling, someone else may think is too much.”

TIME Research

You Asked: Is Cracking Your Knuckles Bad?

Illustration by Peter Oumanski for TIME

And just what is that cracking sound, anyway?

From fingers and toes to necks and knees, everyone knows a “cracker.” And most habitual joint poppers have heard rumors their habit may cause arthritis. But are those rumors true?

First, a quick anatomy lesson: Many of your joints—including those that allow your fingers to beckon or point—feature small pockets or gaps that are filled with synovial fluid. Like axle grease, this fluid allows the bones that commingle in your joints to glide close to one another without grating, explains Dr. Pedro Beredjiklian, chief of hand and wrist surgery at Philadelphia’s Rothman Institute.

When you pull, twist or otherwise “crack” a joint, you’re expanding the volume of space between your bones, Beredjiklian says. That volume expansion creates negative pressure, which sucks the synovial fluid into the newly created space. This sudden inflow of fluid is the popping you feel and hear when you crack a knuckle, he adds.

The more you crack your joint, the more you stretch and loosen both its capsule and the surrounding ligaments. And the looser those components become, the more easily your joint will pop, Beredjiklian says.

So is this bad for your joints? Almost certainly not, he assures. Multiple studies have looked into the prevalence of “crackers” among large groups of osteoarthritis patients. They found no evidence that finger pullers and poppers are more likely to suffer from arthritis than those who don’t crack their knuckles. One devoted researcher—a man who habitually cracked the joints on his left hand—actually studied himself. After roughly six decades of lopsided joint popping, this case study of one showed no increased presence of arthritis in his left hand as opposed to his right.

“Finger cracking is so common you would expect to see a lot of causal reports if it was harmful,” Beredjiklian says. “But you don’t. So I think it’s unlikely cracking joints in hands leads to arthritis.”

While one 1990 study linked long-term joint popping to hand swelling and lower grip strength, there isn’t any more research to back up that finding. On the other hand (pun intended), at least one study concluded that knuckle cracking offers those who do it a sense of almost therapeutic “release.”

Poppers, you can ignore your fusty aunt or cranky coworker when they try to scare you with talk of debilitating cracking-related ailments.

Just one note of caution: Tendons catching on irregular bone or joint formations can also explain some clicking or popping sounds, especially in places like your neck, Beredjiklian says. Whether this can cause harm will depend on the person and his or her anatomy. But if a weird sound emanates from your shoulder or knee when you flex it a certain way, you may want to avoid angering that area with deliberate cracking.

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