There is no benefit to doing more than five hours of high-intensity (高强度) exercise a week, a Harvard study has found, as it does not help to stave off an early death. However, pushing your body as hard as you can does not have any damaging health effects.

A 30-year Harvard study of 100,000 Americans looked at how exercise impacted a person’s risk of death. It found that doing 75 minutes of intense exercise a week, the recommended amount, reduces the risk of dying from disease by 31 percent. People who do twice this—two and a half hours of intense exercise a week—see slightly greater benefits, further reducing the threat of death by four percent. However, fitness enthusiasts who do more than four times the recommended amount of intense exercise every week—five hours—do not get any additional benefit.

The same trend is seen for moderate (适度的) activities, including walking. Ten hours of moderate exercise—four times the recommended weekly activity level—has no benefits, but also no harms.

Previous research had claimed that doing too much exercise could be harmful and may actually increase a person’s risk of early death by putting added pressure on their body. But the new study found that to be untrue, as even people doing more than five hours a week of intense activity showed no bad health effects.

“This finding may reduce the concerns around the potentially harmful effect of engaging in high levels of physical activity observed in several previous studies,” noted Hoon Lee, a study author. “Our study provides evidence to guide individuals to choose the right amount and intensity of physical activity over their lifetime to maintain their overall health.”

More than half a century ago, there were 4, 000 drive-in movie theatres in the United States, and watching a movie from your car was a popular way to spend an evening. But with the number of drive-ins reduced to just a few hundred, outdoor movies have been popping up across the nation. Going to an open-air theatre has become a modern summer pastime for an increasing number of movie fans.

In recent years, outdoor movie screenings have come up in parks, vacant lots (空地) and shopping malls around the nation. On average, about 1, 000 people attend each movie night. It attracts a lot of young professionals, young workers and residents nearby. For some, the outdoor movies bring back the memories of the drive-in theatres of their youths. But for the majorities, they think it is comparable to the atmosphere (氛围) of drive-ins, as they can bring friends, food, good wine, and watch the movie together.

The returning of Americans’ love affair with outdoor movies makes Stephen Bastas ever busier. His seven-member crew sets up screens in various locations mostly in the Washington area every day throughout the summer. They are doing pretty well and they hope to continue the trend. And it looks like they are going to. That’s because many fans say there is nothing like watching a movie on a breezy summer evening under the stars.

We’re all familiar with songs getting stuck in our head while we’re awake, but it turns out this can happen during sleep as well. A new study investigating the phenomenon indicates that earworms invading（侵入）our brains at night could cause problems in getting to sleep and staying asleep.

“Our brains continue to process music even when none is playing, including apparently while we are asleep,” says Michael Scullin.

He and his colleagues used surveys of 199 people, as well as a sleep lab test involving 50 volunteers, to measure how listening to music before bedtime affects sleep. In particular, the team focused on catchy earworms.

Earworms were reported throughout the night by participants, with those catching an earworm taking longer to fall asleep, spending more time in the light stages of sleep, and waking up more times during the night. Surprisingly, the instrumental versions of the songs caused about twice as many earworms and more subsequent sleep problems than the versions with vocal（声乐）

“We thought that people would have earworms at bedtime when they were trying to fall asleep, but we certainly didn’t know that people would report regularly waking up from sleep with an earworm,” says Scullin. “But we saw that in both the survey and experimental study”.

Past studies have linked late-night music listening with better sleep in those with insomnia（失眠）, perhaps because it can relax the body.

Scullin suggests avoiding listening to music right before bed to limit the chance of a catchy tune taking hold in our minds. Engaging in some other cognitive activity before sleeping, like making a list of jobs for the next day, might also help clear the mind, Scullin says.

“Everyone knows that music listening feels good,” says Scullin. “Adolescents and young adults routinely listen to music near bedtime. But sometimes you can have too much of a good thing.The more you listen to music, the more likely you are to catch an earworm that won’t go away at bedtime. When that happens, chances are your sleep is going to suffer.”