Do you have frightening dreams while sleeping? According to an email interview by clinical psychologist and sleep expert Dr. Michael Breus, roughly 5 percent of the general population has at least one bad dream per week. Nightmares typically happen during REM sleep, during the middle and later parts of the night.

There is no exact explanation for nightmares, but Breus says it’s possible that they help the brain practise, prepare for and even predict difficult or dangerous experiences in waking life. Of course, it’s possible that nightmares, like dreams in general, don’t have a primary function — that they’re a by-product of other activities in the body. But most sleep scientists think that dreams and nightmares exist for some purposes.

One study found the most common nightmare was falling, followed by dreams of being chased, feeling lost, and feeling trapped. Then why do nightmares happen?

“Certain circumstances and characteristics make some people more likely to have nightmares than others,” says sleep medicine specialist Dr. Barry Krakow. He thinks people who’ve been traumatized (使受精神创伤) are certainly at a higher risk of nightmares Examples are offered of those who have suffered criminal attacks, or who have been in life-threatening accidents. People with some degree of sensitivity in their biological make-up are also more likely to have bad dreams, so they’re more common in people who suffer from anxiety or depression, or who use excess drugs or alcohol. The traditional belief often has it that nightmares are the result of eating too much rich food before bedtime, but it is still uncertain whether this is true. One study from 2015 did find a link between eating dairy or hot foods before bedtime and having disturbing dreams, but the study authors noted that this couldn’t be proven definitely because the data was self-reported and there were a lot of other factors to consider.

However, research in recent decades has shown that people who suffer from sleep disorders are also more likely to have nightmares.

Old age may not sound exciting. But recent findings offer good news for older people and for people who are worried about getting older. Researchers found that people become happier and experience less worry after they reach the age of 50. In fact, they say by the age of 85, people are happier with their life than they were when they were 18 years old.

The findings came from a survey of more than 340,000 adults in the United States. The Gallup Organization questioned them by telephone in 2012. At that time, the people were between the ages of 18 and 85. The researchers asked questions about emotions like happiness, sadness and worry. They also asked about mental or emotional stress.

Arthur Stone in the Department of Psychiatry and Behavioral Science at Stony Brook University in New York led the study. His team found that levels of stress were the highest among adults between the ages of 24 and 25. The findings showed that stress levels dropped sharply after people reached their fifties.

The study also showed that men and women have similar feeling patterns as they grow older. However, women at all ages reported more sadness, stress and worry than men.

Researchers say they do not know why happiness increases as people get older. One theory is that, as people grow older, they grow more thankful for what they have and have better control of their feelings. So they spend less time thinking about bad experiences. Professor Stone says the emotional patterns could be connected to changes in how people see the world, or maybe even changes in brain chemistry.

The researchers also considered possible influences like having young children, being unemployed or being single. But they found that influences like these did not affect the levels of happiness and well-being related to age.

There is a myth that people can see glass, but birds can’t. 【小题1】

Many people are injured every year. They collide with unmarked doors and windows; embarrassment is the usual result. 【小题2】Because of their small size and high-speed flight, they are usually killed or receive injuries that will likely kill them.

Birds can learn to avoid glass. For example, birds in zoo exhibits learn to avoid exhibit walls if the glass is marked for the first few days of their residence. 【小题3】But overall, birds don’t seem to be able to generalize clues that windows are present, and frequently don’t survive the first impact.

Birds hit glass because it presents a triple threat. One is that reflections of vegetation or landscape attract birds to collide with glass. 【小题4】Besides, glass corners or narrow passages can allow birds to see through to habitat on the other side of a building, and they die trying to fly through.

As researchers have begun to understand collisions, they are creating better approaches to reduce impacts on birds. For example, some have documented mortality(死亡) patterns and how they are influenced by lighting, the amount of glass present, the distribution of nearby vegetation, and other variables. 【小题5】

This science has come along way, but many questions remain unanswered. Our efforts on the testing of bird-friendly materials are helping to expand understanding of how birds sec and respond to their environment, and will lead to more effective solutions.