The COVID-19 pandemic has spread far and wide. Because of this, countries around the world have carried out measures to help stop the virus in its tracks. As more people stay inside to stay safe, the outside world seems to have become much quieter. In fact, scientists have seen this change in their research.

Seismologists - scientists who study earthquakes - have heard a lot less seismic（地震的） noise recently.

Seismic noise is made from vibrations (continuous shaking movements) in the ground that are caused by things like ocean waves and human activity, such as construction work and traffic. This noise makes it difficult for scientists to pick up seismic activity that is made at the same frequency.

Thomas Lecocq, a scientist at the Royal Observatory of Belgium, located in Brussels, was the first to notice this phenomenon. According to Lecocq, the amount of seismic noise in Brussels has been reduced by about 30 to 50 percent since mid-March. Interestingly enough, this is around the same time Belgium started its measures. Because of this reduction in background noise, scientists like Lecocq have been able to pick up on smaller earthquakes that some seismic stations - like the one in Brussels - wouldn’t have been able to before.

This phenomenon isn’t unique to Brussels, though. Once Lecocq shared his findings online, seismologists from all over the world echoed similar findings. Celeste Labedz, a graduate student at the California Institute of Technology, mentioned in a tweet that Los Angeles also experienced less background noise. “The drop is seriously wild,” she wrote.

Researchers from the UK, France and New Zealand also noted a decrease in background noise since measures were put in place.

These global efforts to contain the COVID-19 virus have helped to shed light on seismic activity that may have gone unnoticed. It also shows that people are listening to health officials and following lockdown rules. “From the seismological point of view, we can motivate people to say, ‘You feel like you’re alone at home, but we can tell you that everyone is home. Everyone is respecting the rules,’” Lecocq told CNN.

There are breathing robots versed in “thousands of years of Buddhist breathing techniques” that claim to soothe you to sleep. Then there are weighted blankets that press around 10% of your body weight down as you take a nap. And there are apps, such as supermodel Natalia Vodianova's Loona, designed to create a "sleepscape" by combining visual and aural storytelling with relaxation-based activities such as colouring in. These are just some of the products at the heart of the “sleep aid revolution”.

Sleep occupies almost as much of the national conversation as weather—how much, when, how deep it is—and we are more than prepared to spend our money on more, and better, shut-eye.

In the past 12 months, sales of sleep-related products have soared. At John Lewis, silk pillowcase sales have increased by 533%. At weighted blankets company Mela, sales are up by 250%, while at Holland & Barrett sales of products in the sleep and relaxation category have grown by over 30% year-on-year.“ sleep” is the third most common unique search term for visitors to Neal's Yard Remedies' site.

But there are some dissenting voices. "The sleep-aid industry steps in, with claims that we're not sleeping because it's time for a new mattress, and offers us products to enable sleep," says Darian Leader, author of Why Can't We Sleep? “However," he points out, “what we are seeing is a depoliticizing of sleep - ignore the socio-economic burdens and internal pain that people face and see lack of sleep as a separate problem with a 'separate solution'."

The growing interest isn't limited to those suffering from diagnosable sleep issues—sleep has become a pillar of the wellness market and tracking it has become another symptom of the rise of the quantified self, a movement that sees people tracking their every step.

Sleep expert Dr. Neil Stanley distrusts the market: “It is a trick to scare everybody because nobody's going to make any money if you just go around saying 'it's common sense, you know how to sleep' .”

While rebutting any scientific evidence for many of the products, he admits that anything—a silk pillowcase, camomile tea, yoga or listening to Pink Floyd really loudly - could, in theory, help.

But, he says, many are overlooking the simple things. "You need three things for a good night's sleep: a bedroom that's comfortable, a relaxed body and a quiet mind ... you need to make space in your life for sleep.”

The biggest safety threat facing airlines today may not be a terrorist with a gun, but the man with the portable computer in business class. In the last 15 years, pilots have reported well over 100 incidents that could have been caused by electromagnetic interference. The source of this interference remains unconfirmed, but increasingly, experts are pointing the blame at portable electronic device such as portable computers, radio and cassette players and mobile telephones.

RTCA, an organization which advises the aviation (航空) industry, has recommended that all airlines ban such devices from being used during “critical” stages of flight, particularly take-off and landing. Some experts have gone further, calling for a total ban during all flights. Currently, rules on using these devices are left up to individual airlines. And although some airlines prohibit passengers from using such equipment during take-off and landing, most are reluctant to enforce a total ban, given that many passengers want to work during flights.

The difficulty is predicting how electromagnetic fields might affect an aircraft’s computers. Experts know that portable device emit radiation which affects those wavelengths which aircraft use for navigation and communication. But, because they have not been able to reproduce these effects in a laboratory, they have no way of knowing whether the interference might be dangerous or not.

The fact that aircraft may be vulnerable to interference raises the risk that terrorists may use radio systems in order to damage navigation equipment. As worrying, though, is the passenger who can’t hear the instructions to turn off his radio because the music’s too loud.