TIME Research

The Link Between Asthma and This Chemical

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Bisphenol A molecule Laguna Design/Getty Images

Bisphenol A, or BPA, lurks in the plastics of all kinds of consumer goods, from can linings to plastic bottles—but its influence doesn’t end with the product. BPA is an endocrine disruptor that can leach into food and is linked to all kinds of health problems from aggression to obesity. Now, a new study published in JAMA Pediatrics finds that prenatal exposure to BPA is also linked to lower lung capacity in some young children.

MORE: How BPA May Disrupt Brain Development

The study looked at urine samples of 398 mother-infant pairs, both during and after pregnancy. Every 10-fold increase in the BPA concentration of maternal urine—meaning every time that number went up 10 times—was linked to about a 55% increase in the odds of wheezing. Lung capacity was also affected: Higher BPA concentrations during pregnancy were also linked to decreased lung capacity in four-year-olds, but by age 5, that link disappeared. Once a child was born, the BPA levels in their own urine weren’t associated with wheeze at all.

Exposure during pregnancy, not after, appears to be the critical time for BPA, possibly because it’s affecting important pathways that help the lung develop, says study author Adam Spanier, MD, PhD, associate professor of pediatrics at the University of Maryland School of Medicine.

That link between prenatal BPA exposure and wheeze might be reflective of asthma, Spanier says, which would be consistent with what animal models are finding. “Some animal studies out there suggest that BPA prenatally might affect the development of some of the cells in our airway,” he says. Asthma has been on the rise for the past three decades, and environmental exposures like BPA are thought to be a possible link. A 2013 study also found a link between BPA and asthma, and though the mechanism behind the connection is complex and unclear, Spanier sees a definite association. “If my sister who’s pregnant asked me for advice, I would tell her try to minimize her BPA exposure,” he says. “I wouldn’t say let’s do some more research.”

TIME Research

Why Climate Change Affects Poor Neighborhoods The Most

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Scientists frequently tout new evidence that climate change will drive some of the most populated cities in the United States underwater. New York, Boston and Miami are all at risk. But the impact of climate change varies even within cities, putting residents of poor neighborhoods at greatest risk of suffering from heat-related ailments, researchers say.

“Cities tend to be warmer, but it’s spatially variable within cities,” says Joyce Klein Rosenthal, a researcher at Harvard who published a recent study on the impact of climate change in cities. “Generally, higher poverty neighborhoods are warmer and wealthier neighborhoods are cooler.”

This difference in neighborhood temperatures affects senior citizens and correlates with a disparity in their mortality rates due to heat-related causes, a study of New York City led by Rosenthal suggests.

This higher rate in poor neighborhoods isn’t just because lower-income families aren’t always able to afford owning and operating an air conditioner, though that certainly contributes to the problem. Poor neighborhoods often have few trees and have buildings that tend to be constructed from materials that retain heat, Rosenthal said.

Climate change also affects these areas more because of the professions of some of the residents, according to Olga Wilhelmi, a researcher at the University Corporation for Atmospheric Research. Laborers who work outside all day in extreme temperatures and return home to a hot apartment are more likely to experience heat stroke or another heat-related ailment.

“It’s not just your housing conditions but whether or not you have a choice to modify your daily behaviors and routine to better cope with extreme temperatures,” says Wilhelmi.

As scientists grapple with long-term solutions to climate change, policymakers need to consider a entirely new set of solutions to address the health risks posed by extreme heat in cities.

Ironically, many of the methods used to address climate change broadly are ineffective, if not problematic, for handling heat stroke at the neighborhood level. For one, while public awareness campaigns encourage people to use less electricity, residents of poor neighborhoods should probably turn up the air conditioning while their counterparts in wealthier, cooler neighborhoods may not.

Wilhelmi says that some cities including Chicago have begun to implement measures like heat warning systems to warn vulnerable populations about extreme heat conditions.

Still, changing factors like building codes and urban design isn’t always easy, making fundamental improvements potentially generations away.

TIME Research

Why Pregnant Women Who Smoke Might Have Kids With Worse Sperm

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One more bullet point on a long list of reasons to quit smoking

Add diminished fertility to the long list of reasons why women should avoid smoking while pregnant or breast feeding. The mice sons—called pups—of mothers exposed to the smoke equivalent of a pack of cigarettes a day during that time wind up with sperm that struggle in the reproduction process, according to a new study in mice published in the journal Human Reproduction.

“Our results show that male pups of ‘smoking’ mothers have fewer sperm, which swim poorly, are abnormally shaped and fail to bind to eggs during in vitro fertilisation studies,” said study leader Eileen McLaughlin, a chemical biology professor at the University of Newcastle in Australia, in a press release. “Consequently, when these pups reach adulthood they are sub fertile or infertile.”

Unlike previous research, the new study looked at pregnancy in mice to try to determine not just the consequences of smoking during pregnancy but also the mechanism behind it. Cigarette toxins affect the stem cells in the testes, McLaughlin says, which results in permanently lowered sperm production—and these results likely apply to humans, she adds. “We also know that oxidative stress induced by these toxins causes damage to the nuclei and mitochondria (the cell’s ‘power’ supply) of cells in the testes and this results in sperm with abnormal heads and tails, that are unable to swim properly or successfully bind and fuse with eggs.”

The knowledge that smoking has devastating long-term implications for the health of children is nothing new. Previous studies have suggested that smoking stems fetus growth, leads to premature delivery and causes birth defects. Nonetheless, 20% of women in the United States continue to smoke during pregnancy. The number is higher in Australia, where the study was conducted.

“We would ask that smoking cessation programmes continue to emphasise that women should avoid smoking in pregnancy and while breast feeding as the male germ line is very susceptible to damage during early development and the resulting sub fertility will not be apparent for several decades,” said McLaughlin.

TIME Research

How Your Sense of Smell Is Linked to Your Lifespan

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Older adults who suffer an impaired olfactory sense are more likely to die within five years, say researchers

The loss or erosion of an individual’s sense of smell may signal impending death, according to a new study.

Researchers at the University of Chicago found 39% of subjects who failed olfactory sense tests died within a five-year period, compared with 19% of subjects with moderate smell loss and just 10% who retained a healthy sense of smell.

This mean the loss or degradation of the olfactory sense may serve effectively as an “early warning” signal that something has gone very wrong inside the body, says the study published in the journal PLOS One on Wednesday.

“We think loss of the sense of smell is like the canary in the coal mine,” said the study’s lead author Dr. Jayant Pinto. “Our findings could provide a useful clinical test, a quick and inexpensive way to identify patients most at risk.”

The research was conducted in two waves over the course of more than five years and surveyed approximately 3,000 adults.

TIME History

Archaeologists Believe They Found Dracula’s Dungeon

Circa 1450, Portrait of Vlad Tepes 'Vlad the Impaler'(c 1431-1476), from a painting in Castle Ambras in the Tyrol.
Circa 1450, portrait of Vlad Tepes or Vlad the Impaler, from a painting in Castle Ambras in the Tyrol Stock Montage/Getty Images

The dungeon believed to have held Vlad the Impaler, the inspiration for the blood-thirsty character, was recently discovered in Turkey

Archeologists in Turkey have reportedly made a spooky discovery, just in time for the start of Halloween season: the dungeon where the real-life basis for Count Dracula was held.

The cell where history’s Dracula, the Romanian prince Vlad III (nicknamed Vlad the Impaler for his gruesome tendency to impale his foes), was recently discovered during a restoration project, the Turkey-based Hurriyet Daily News reports.

Researchers are reportedly restoring the ancient Tokat Castle, where the Ottomans imprisoned the infamously cruel figure, in the mid 1400s. The team there evidently discovered a tunnel leading to two dungeons — one of which is likely to have housed Bad Old Vlad.

TIME Sex/Relationships

Teenage Girls Given Choice of Free Contraceptives Get Far Fewer Abortions

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Illustration by Miles Donovan for TIME

Girls allowed to choose between free contraceptive methods had 76% fewer abortions than their peers in the general population — and most chose IUDs

Three in 10 teenage girls in the U.S become pregnant each year—a rate far higher than in other industrialized countries. But when girls are counseled about the most effective contraceptives and given their pick of birth control at no cost, their rates of pregnancy drop by 78% and they get 76% fewer abortions than the general population of sexually active teens.

That’s what a new study published in the New England Journal of Medicine suggests, in which researchers at Washington University School of Medicine in St. Louis attempted to see what would happen when they tore down the three main barriers to teenage birth control—ignorance of options, limited access and prohibitive cost.

They studied a group of 1,404 teenage girls enrolled in the Contraceptive CHOICE project, a study of adolescents and women at high risk for unintended pregnancy. 62% of the girls were black and 99% were sexually active. Black teens have even higher rates of pregnancy than the rest of the population: 4 in 10 become pregnant, compared with 2 in 10 white teens.

In the study, peer educators, volunteers, medical students and others interested in health education counseled the girls on the available methods, presenting them in order of effectiveness—IUDs and implants, followed by Depo-Provera injection, pills, patch and ring, and condoms. They stuck to a script that encouraged the girls to choose for themselves, emphasizing that they can always change their method later. The contraceptives were in the room for the girls to see and touch. The clinic had flexible scheduling so that even if a teen was late to her appointment, she was guaranteed to be seen, and every girl received her birth control right after the counseling session.

That’s a world away from the experience of girls in the outside world, who are often asked by providers to come back several times before they start a method, given false information about IUD risks, and eventually mass-prescribed pills, says project director Gina Secura. “It’s often a one-sentence conversation: what do you want, and here’s a prescription,” she says.

MORE: How Having an (Insurance-Covered) IUD Is Saving My Life

Focusing the conversation purely on effectiveness was, well, extremely effective. “When we first started the project, we had hoped to double the national rate [of IUD or implant use]—about 5%,” says Secura. Instead of the hoped-for 10%, a whopping 72% of teems chose IUDs or implants. “We were shocked,” she says. And they stuck with them. Two-thirds of the girls were still on long-acting reversible contraception (LARC, which includes implants and IUDs) after 2 years, compared to one third of girls on short-acting methods like the pill.

IUDs are a solid choice according to the American Academy of Pediatrics, who just endorsed IUDs as the best method of birth control for teenage girls. And the evidence bears it out. The researchers tracked the girls for 2-3 years and followed up every few months by phone. They found that 3.4% of CHOICE teens got pregnant, compared to 15.85% of sexually experienced teens in the general population. Fewer than 1% of CHOICE teens got abortions (0.97%, to be exact), while 4.15% of the other population did.

That means that girls in the program were 78% less likely to get pregnant and had 76% fewer abortions than their peers in the general population. Of course, it’s not quite fair to compare these two groups, since the girls in the research project were given free access and would have been more encouraged to stick to their methods with follow-ups, but the implications are incredibly important for clinics and counselors.

Most notable of all, the low pregnancy rates between white and black teenagers in the project were almost identical. “If we really want to tackle this health disparity, that shows we can actually do it,” Secura says.

These rates far outpace even the CDC’s 2015 goal for teenage births; they’re aiming for 30.3 teenage births per 1,000 teens. The CHOICE rate was 36% lower than that, at 19.4 teenage births.

Secura attributes these dramatic drops largely to the high uptake of long-term contraceptive methods, options that are cost-prohibitive to many low-income teens and free clinics. “It can be difficult to justify spending the same amount of money on 10 devices, where they could buy five times as many packs of pills,” Secura says.

The researchers put their CHOICE methods on a site called LARC FIRST designed to guide clinics, and since data from the study began coming out over the past two years, Secura says they’ve gotten about 300 requests from clinics asking for help in implementing their best practices—including training people who aren’t time-pressed providers and nurse practitioners to deliver effectiveness counseling. Having a kind of AmeriCorps for contraceptive effectiveness counselors, Secura says, would be a dream.

Though the study is over, several clinics are trying to adapt some of CHOICE’s methods to their real world practices and evaluate them scientifically. “I’m hoping we build the demand in terms of teens wanting these,” Secura says.

TIME has called IUDs the best form of birth control that no one is using—but when teens are informed and cost barriers disappear, this study shows that teenage girls are clearly hungry for better birth control.

TIME Research

You Asked: Is It Good or Bad to Take a Nap?

Illustration by Peter Oumanski for TIME

Snooze, or skip it?

You’re right to be confused. Even as a recent study linked napping to higher mortality, companies and colleges across the U.S. are installing nap rooms to boost productivity. Truly, it would be a dream to get some napping consensus.

But whether or not napping is right for you depends. “First of all, it’s important to ask yourself why you’re taking the nap,” says Dr. Sara Mednick, a psychologist at the University of California, Riverside and author of Take a Nap! Change Your Life. If you’re spending a big chunk of your day feeling sleepy and out of sorts, then your desire to snooze may be driven by stress, insomnia, sleep apnea or a hundred other slumber-disrupting health conditions, Mednick says.

“Daytime napping is an early indicator of underlying ill health,” adds Yue Leng, a University of Cambridge sleep researcher and coauthor of the study linking naps to higher mortality rates. Like Mednick, Leng suggests daytime drowsiness is likely a symptom of other health issues, not their cause.

Put simply, blaming naps for higher mortality rates is like blaming your doctor for heart disease; you’re more likely to see a doc if you have heart issues, but that doesn’t mean she’s to blame.

MORE: The Power of Sleep

Actually, naps are good for most people, Mednick says. Her research shows a nap—defined as daytime sleeping that lasts between 15 and 90 minutes—can improve brain functions ranging from memory to focus and creativity. “For some people, naps are as restorative as a whole night of sleep,” she adds. More research shows a quick nap can lower stress and recharge your willpower. And napping has also been linked to lower rates of cardiovascular disease and inflammation.

But all of these benefits depend on you getting a good night of sleep to begin with, Mednick stresses. Also, not everyone is a good napper. “Some people wake up from naps feeling like crap,” she says.

Genetics could explain why some people are nappers and some aren’t. But regardless of the explanation, there’s clearly a difference between the two groups. “People who aren’t habitual nappers tend to fall into very deep sleep during naps, and waking up from that leaves them feeling groggy,” Mednick explains. On the other hand, natural nappers—you know who you are—don’t plunge into deep slumber during their daytime snoozes, Mednick says. This allows them to wake up from naps feeling energized and alert, not discombobulated.

MORE: Pass The Pillow: “Google Naps” Is Google Maps for Places to Nap

For natural nappers, she says it’s “incredibly important” that you do catch your daytime ZZZs. “These people—and they probably account for about 40% of the population—tend to do really poorly if they don’t nap,” she explains. Without their much needed daytime shuteye, habitual nappers often reach for energy drinks, caffeine or other stimulants that perk them up but don’t recharge their cognitive batteries the way a short, healthy snooze would.

“For these people, skipping their nap is a huge productivity killer,” Mednick says, and that’s a compelling reason for employers and universities to provide nap spaces for employees and students.

While the length of an ideal siesta varies from person to person, 20 to 30 minutes is plenty for most. But up to 90 minutes—about the length of one full sleep cycle—could also be beneficial, Mednick says. She recommends trying different nap lengths to find the one that leaves you feeling the most refreshed.

If you’ve never been a napper but want to cash in on napping’s brain and health benefits, Mednick says you may be able to teach yourself to nap. The trick is to keep your daytime shuteye very short—no more than 15 minutes at first. This will prevent your brain and body from slipping into the deeper levels of slumber that leave you feeling foggy upon waking, she adds.

But if you’re just not a born napper, don’t sweat it. “Everyone’s different,” Mednick says. “If you feel good, whatever you’re doing is fine.”

TIME Mental Health/Psychology

The Reason You Make Unhealthy Choices

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Self love isn’t just for hippies and millennials. If you’re trying to stick to a diet or scrape together the motivation to get to the gym, it might be for you, too.

So finds a new meta-analysis published in the journal Health Psychology. Self-compassion—accepting yourself without judgment when times get tough—is linked to better health behaviors.

People often think that they are motivated by self-criticism, but a burgeoning area of research suggests the opposite. Being kind to yourself, as opposed to tearing yourself down, leads to fewer bad feelings and, in turn, healthier actions. One study found that when people were assigned to practice self-compassion, they were able to curb their smoking habit faster. The reason self-compassion works, researchers think, might be its ability to improve self-regulation: the follow-through you need to stay loyal to healthy behaviors.

This analysis looked at 15 studies of more than 3,000 total people across the age spectrum and discovered a link between self-compassion and four key health-promoting behaviors: eating better, exercising more, getting more restful sleep, and stressing less. People who were more self-compassionate practiced these health habits more often.

“So much research right now is suggesting that not engaging in these behaviors can be the precursor to a variety of different life-threatening and chronic diseases such as diabetes, hypertension, cardiovascular disease, arthritis, you name it,” says study author Fuschia Sirois, professor of psychology at Bishop’s University in Quebec. Developing self-compassion is a way to commit to the behaviors you already know you should do, she says.

In addition to just being nice to yourself, self-compassion requires you to embrace that you’re part of the human race that shares common miseries, and mindfully recognize negative feelings without getting enmeshed in them. If that sounds impossible, Sirois assures us it’s not.

“One of the reasons we were quite excited by the findings is that self-compassion is a quality that can be cultivated,” says Sirois. Writing a letter to yourself—as if you were your own friend—and opening it up in times of stress or failure is one way to start, she suggests. Kristin Neff, a pioneer in this field of research, offers guided self-compassion meditations and exercises on her site.

Find out where you currently fall on the scientific scale for self-love here.

TIME Aging

‘Senior Moments’ Could Be Early Signs of Dementia: Study

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Scientists hope that early identification of warning signs may help prevent memory problems from becoming so severe

So-called senior moments, like failing to recall your missing sunglasses are perched on your head, might not be just benign mishaps, but early harbingers of Alzheimer’s disease, reports a new paper.

The study, published in the journal of the American Academy of Neurology, suggests that self-reported worries about memory lapses are strong predictors of a later diagnosis of dementia. The research indicates that it takes about 12 years from initial signs of forgetfulness for the problem to become severe enough to be called dementia.

Of course, forgetfulness is a natural part of aging, and a spotty memory by no means guarantees that bigger problems are in the works, the researchers say. However, that does not mean concerns about errant sunglasses should necessarily be brushed off.

That’s because “there may be a significant window of opportunity for intervention before a diagnosable problem shows up,” Richard Kryscio, the study’s lead author and associate director of the Alzheimer’s Disease Center at the University of Kentucky, said in a statement. “Certainly, someone with memory issues should report it to their doctor so they can be followed.”

Right now, there are no definitive ways of preventing dementia, though early research suggests that a healthy lifestyle — including exercise, good eating habits and abstention from smoking — might help ward off the disease, the National Institutes of Health says. Antianxiety drugs have also recently been fingered as possibly increasing a user’s risk of developing memory problems later in life.

In the study, scientists at the University of Kentucky asked 531 people, average age 73 and without dementia, if they had noticed any changes in their memory in the past year.

People who reported such changes were about three times more likely to develop dementia than those who reported no such symptoms. In fact, of the 1 in 6 participants who developed dementia, 80% of those first reported memory changes.

Meanwhile, separate research published in Cognitive and Behavioral Neurology suggests that people with dementia may not remember specific events, like a visit from a relative, but do remember how those forgotten events made them feel.

“This confirms that the emotional life of an Alzheimer’s patient is alive and well,” Edmarie Guzman-Velez, lead author and a doctoral student in clinical psychology at the University of Iowa, said in a statement. “Our findings should empower caregivers by showing them that their actions toward patients really do matter.”

In the study, 17 people with Alzheimer’s disease and 17 healthy participants were asked to view 20 minutes of sad and happy movies. About five minutes after each movie clip finished, participants took a test on what they’d watched: though participants with dementia remembered much less about films than did the nondementia participants — one didn’t remember watching any movies — they still reported heightened levels of either sadness or happiness for up to 30 minutes after watching the films, according to the research.

In general, the researchers said, sadness lasted longer than happiness.

TIME Innovation

Five Best Ideas of the Day: September 24

The Aspen Institute is an educational and policy studies organization based in Washington, D.C.

1. Because of America’s unique relationship with Liberia, we have an obligation to help fight the Ebola outbreak there.

By James Ciment in Slate

2. Medical research often doesn’t account for different ethnicities, and underrepresented groups suffer.

By Estaban G. Burchard in Nature

3. One way to head off sexual violence in professional sports: start with high school coaches.

By Libby Nelson in Vox

4. Beyond the sharing economy: Is “reputation” the next important currency?

By Heather Schlegel on CNN

5. Powerful protests over climate change target corporations – and new leadership is needed to restore faith in capitalism.

By Judith Samuelson in the Huffington Post

The Aspen Institute is an educational and policy studies organization based in Washington, D.C.

TIME Ideas hosts the world's leading voices, providing commentary and expertise on the most compelling events in news, society, and culture. We welcome outside contributions. To submit a piece, email ideas@time.com.

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