Health & Science

To dream, perchance to learn

A good night’s sleep and even a nice nap can boost your brain’s ability to remember and learn new information. But dreams can help even more, a new study suggests. For the Harvard study, 100 volunteers were asked to take a test on a computer that involved finding their way around a maze. After a five-hour break, they took the test again. Those who had stayed awake in the interim improved their time by an average of 26 seconds, while subjects who took a 90-minute nap did much better, improving their time by 188 seconds. But the most dramatic improvements were among the four who actually dreamed about the test; their performances improved 10 times as much as the nondreamers’. “I was startled by this finding,” Harvard neuroscientist Robert Stickgold tells Science News. “This study tells us that dreams are the brain’s way of processing, integrating, and really understanding new information.” Researchers suspect that dreams don’t directly improve memory; rather, they’re byproducts of a deeper thought process in which memories are being integrated. In any event, “if you’re studying something tough, get the basics down and take a nap,” says sleep researcher Michael Breus. “If you dream about it, you will probably understand it better.”

Elephants sound the alarm

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African elephants are terrified of bees, which tend to sting them around their eyes and inside their trunks. Now British scientists have recorded a distinctive call, or “bee rumble,” that the pachyderms make as they flee a buzzing swarm. To determine if the rumble actually serves as an alarm, researchers broadcast the recording to 10 elephant herds; six of the herds fled, even shaking their heads as if to deflect bees. “It not only provides the first demonstration that elephants use alarm calls,” behavioral ecologist Karen McComb of the University of Sussex tells ScienceNOW, “but also shows that these may have very specific meanings.” Researchers will now try to determine if elephants also have warning calls to alert their herd to other dangers, such as lions and humans.

Why people crave chocolate

If you find yourself reaching for chocolate when you’re feeling down, you’re not alone. Researchers have found that depressed people eat twice as much chocolate as nondepressed ones do. More than 900 subjects were screened using a standard mood scale and surveyed about their chocolate intake. Respondents with the fewest signs of depression ate a bit more than five 1-ounce servings of chocolate a month. People who seemed somewhat depressed ate eight servings a month, while those with major depression ate 12. The study supports the notion “that when people need a pick-me-up, they pick up chocolate,” Beatrice Golomb of the University of California at San Diego tells CNN.com. Eating chocolate is known to release brain chemicals that can lift mood, though it’s also possible that the subsequent crash could drive depression. In either case, the chocolate urge may be a telling sign. “If you crave chocolate a lot,” says psychologist Scott Bea of the Cleveland Clinic, “examine your mood state and deduce if depression is a factor in your life.”

The mirth diet

It’s been said that laughter is good medicine, but it also may be good exercise, says LiveScience.com. In a series of studies, researchers at Loma Linda University in California found that repeated bouts of “mirthful laughter” offer some of the same benefits—including lower blood pressure and lower cholesterol—as moderate exercise. In their most recent study, researchers found that volunteers who laughed while watching videos experienced changed levels of the hormones ghrelin and leptin, which are known to regulate appetite. Those hormones are also affected by exercise. The findings, says study author Lee Berk, suggest that some sort of “laughter therapy” might be an option for patients who cannot use physical activity to normalize or enhance their appetite.

Chimps grieve, too

Humans mourn the death of loved ones with an intensity that seems unique among animals. But two studies suggest that chimpanzees react to death in ways “strikingly similar” to our own responses, British psychologist James Anderson tells ScienceNOW. Anderson witnessed a female chimp in her 50s, named Pansy, slowly pass away at a zoo in Scotland. As Pansy faded and expired, other chimps kept a close vigil, groomed her incessantly, and were uncharacteristically subdued for a week afterward. Separately, primatologists in Guinea came across two female chimps toting long-dead infants on their backs. The remains were effectively mummified, yet the mothers kept them close and even groomed them. The findings “make a strong case that chimps not only understand the concept of death but also have ways with which they cope with it,” Anderson says. “The boundaries between us and other species are nowhere near as clearly defined as many people used to think.”