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Men and Women Have Very Different Types of Nightmares

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In the middle of a pleasant dream, something lurks in the shadows. Soon, the nonsensical reverie takes a dark turn and something starts stalking you. What is it? You wake, heart racing, breathing rapidly. That nightmare felt horrible, but was the terrible creature haunting your dream a masked killer or just your mom criticizing your clothing?

The answer depends on your gender.

Geneviève Robert and Antonio Zadra, researchers from the University of Montreal, asked more than 550 subjects to keep dream journals for two to five consecutive weeks, resulting in the records of a total of 9796 dreams. The researchers then analyzed the dreams, finding that of the almost 10,000 dreams, there were 431 bad dreams—which cause some unpleasant feelings—and 253 nightmares, which include an emotion so disagreeable that it wakes people from sleep. Subjects said that nightmares felt more “emotionally intense” than bad dreams.

“[N]ightmares were more bizarre and contained substantially more aggressions, failures, and unfortunate endings,” the study says. Only 331 of the participants experienced unpleasant dreams. They found that 35 percent of nightmares and 55 percent of bad dreams involved emotions other than fear.

After looking at the nightmares for general content, the researchers looked at more specific themes and found the stuff of nightmares varied by gender. Women had nightmares that focused on interpersonal strife—a fight with a partner, a disagreement with a mother-in-law, a conflict with a willful child. The emotions involved in those nightmares included feelings of humiliation, inadequacy, and frustration.

Men, on the other hand, tended to have nightmares about natural disasters (floods, earthquakes, fires and volcanoes), chases, and bugs. The women’s nightmares frequently involved a friend or family member trying to navigate the scary situation with them, while the men worked alone in their nightmares. On average, they found that women experienced more nightmares than men.

“The results have important implications on how nightmares are conceptualized and defined," the researchers wrote, "and support the view that, when compared to bad dreams, nightmares represent a somewhat rarer—and more severe—expression of the same basic phenomenon.”

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Health
Growing Up With Headphones May Not Damage Kids’ Hearing
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A study published in the American Medical Association's JAMA Otolaryngology-Head & Neck Surgery finds no increase in child and adolescent hearing loss despite a rise in headphone and earbud use.

"Hearing impairment in children is a major public health burden given its impact on early speech and language development, and subsequently on academic and workforce performance later in life," the authors write. "Even mild levels of hearing loss have been found to negatively affect educational outcomes and social functioning."

As portable music players continue to grow in popularity, parents, doctors, and researchers have begun to worry that all the music pouring directly into kids' ears could be damaging their health. It seems a reasonable enough concern, and some studies on American kids' hearing have identified more hearing loss.

To take a closer look, researchers at the University of California-San Francisco analyzed data from the National Health and Nutrition Examination Survey (NHANES), collected from 1988 to 2010. They reviewed records from 7036 kids and teens between the ages of 12 and 19, checking each participant's hearing tests against their exposure to noise.

As expected, the authors write, they did find a gradual increase in headphone use and other "recreational noise exposure." And they did see an uptick in hearing loss from 1988 to 2008 from 17 percent to 22.5 percent. But after that, the trend seemed to reverse, sinking all the way down to 15.2 percent—lower than 1988 levels. They also found no significant relationship between noise exposure and hearing loss.

The results were not uniform; some groups of kids were worse off than others. Participants who identified as nonwhite, and those of lower socioeconomic status, were more likely to have hearing problems, but the researchers can't say for sure why that is. "Ongoing monitoring of hearing loss in this population is necessary," they write, "to elucidate long-term trends and identify targets for intervention."

Before you go wild blasting music, we should mention that this study has some major limitations. Hearing loss and other data points were not measured the same way through the entire data collection period. Participants had to self-report things like hearing loss and health care use—elements that are routinely under-reported in surveys. As with just about any health research, more studies are still needed to confirm these findings.

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Weather Watch
NASA Figures Out Why When It Rains, It (Sometimes) Drizzles
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What’s the difference between drizzle and rain? It has to do with updrafts, according to new research by NASA scientists into the previously unexplained phenomenon of why drizzle occurs where it does.

The answer, published in the Quarterly Journal of the Royal Meteorological Society, could help improve how weather and climate models treat rainfall, making predictions more accurate.

Previously, climate researchers thought that drizzle could be explained by the presence of aerosols in the atmosphere. The microscopic particles are present in greater quantities over land than over the ocean, and by that logic, there should be more drizzle over land than over the ocean. But that's not the case, as Hanii Takahashi and her colleagues at the Jet Propulsion Laboratory found. Instead, whether or not rain becomes full droplets or stays as a fine drizzle depends on updrafts—a warm current of air that rises from the ground.

Stronger updrafts keep drizzle droplets (which are four times smaller than a raindrop) floating inside a cloud longer, allowing them to grow into full-sized rain drops that fall to the ground in the splatters we all know and love. In weaker updrafts, though, the precipitation falls before the drops form, as that light drizzle. That explains why it drizzles more over the ocean than over land—because updrafts are weaker over the ocean. A low-lying cloud over the ocean is more likely to produce drizzle than a low-lying cloud over land, which will probably produce rain.

This could have an impact on climate modeling as well as short-term weather forecasts. Current models make it difficult to model future surface temperatures of the Earth while still maintaining accurate projections about the amount of precipitation. Right now, most models that project realistic surface temperatures predict an unrealistic amount of drizzle in the future, according to a NASA statement. This finding could bring those predictions back down to a more realistic level.

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