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Daylight Saving Time Has a Dark Side

A New York engineer is wheeled away in December 2013, after a train he was driving crashed. Lack of sleep could have been a factor. (Credit: AP Photo/Robert Stolarik)

A train hurtled around a corner at 82 mph, eventually coming off the rails and killing four passengers.

Decades earlier, faulty decision-making resulted in the deaths of the seven-person crew of the Space Shuttle Challenger.

Years before these events, a stuck valve regulating the supply of coolant to a nuclear reactor nearly resulted in the meltdown of a nuclear plant in Pennsylvania. In each of these cases, poor or inadequate sleep was one of the factors that contributed to the failure.

Even if you are not an engineer working in one of those contexts, the odds are pretty good that you occasionally get a poor night’s sleep. In fact, over one-third of American adults sleep less than the suggested minimum seven hours a night and two-thirds of American teens sleep less than their minimum recommended eight hours. Even for those with good sleep hygiene, there is one time of year when you are likely to be short on sleep – the annual shift to daylight saving time.

As an organizational psychologist at the University of Oregon, I have examined a variety of ways in which sleep affects employees. In particular, my colleagues and I investigate how circadian misalignment caused by the shift to daylight saving time leads to costly work and social outcomes.

Even with the extra daylight, the facts don’t look so good

The American public has had a love-hate relationship with daylight saving time since it first became law in 1918. Personal preferences aside, the empirical evidence for the intended benefits of daylight saving time are mixed at best, whereas the costs of the switch to daylight saving time are becoming increasingly evident.

At the crux of these costs is the effect of the time shift on our sleep patterns. When we spring forward, the clocks on the wall advance, but our body clocks do not change so readily. It generally takes a few days for us to adapt to the time change in a way that allows us to fall asleep at our typical time. The upshot is that Americans sleep approximately 40 minutes less than usual on the Sunday to Monday night following the switch.

Along with my colleague, I first examined how the shift to daylight saving time affected workers in blue-collar settings. Using a database of mining injuries from the National Institute of Occupational Safety and Health, we discovered that the spring shift to daylight saving time resulted in a 6 percent increase in mining injuries and a 67 percent increase in workdays lost because of these injuries.

Hazards even if you work above ground

Although these findings might raise some concern, you may have more experience with computers than with mining equipment, and you are probably reading this article at work. It makes sense then to consider how the shift to daylight saving time influences workers in white-collar settings.

We set out to understand these possible effects by examining how people were using their internet access on the day following the time change. By examining internet search patterns over six years in over 200 different American metro areas, we found that searches for entertainment or related categories were much more prevalent (3.1-6.4 percent) on the Monday immediately following the time change than they were on the Mondays before and after the time change. Given that much of this search activity was conducted at work, we concluded that workers are misusing their internet access when they should be working – a behavior called cyberloafing. Such loafing on the job following the time change suggests that people are less productive when mildly sleep deprived due to the time change.


Misusing computers at work can be costly. (Credit: rawpixel/

Based solely on the findings from our two studies, along with a study showing that the time change predicts a 5 percent increased incidence of heart attacks, economists estimate that the annual spring time change costs the American economy US$434 million each year. Yet that is not where the costs end.

Daylight saving time affects our judgment

Our research has also revealed that the shift to daylight saving time influences our ability to perceive the moral features of a given situation. We again examined internet search behavior and followed up with our own experiment. In the experiment we kept half of our research participants awake throughout the night and allowed the other half to get a full night of sleep. The next day we presented them with scenarios that contained varying levels of moral content.


We found that the day following the shift to daylight saving time, or following a night of sleep deprivation, people were less able to discern when a situation involved issues of moral relevance than when they were well rested.

The time change also affects our judgment in formal settings. A recent study found that judges hand out harsher sentences — 5 percent longer in duration — the Monday following the time change, as compared to other days of the year. This means that sleep and public policy related to sleep could be influencing important decisions that should be impartial.

Judges mete out longer sentences after the time change, a study found. (Credit: Denis Simonov/

These studies are only the tip of the iceberg, with adverse consequence of the time change ranging from student test scores to stock market returns.

No matter your sentiment toward daylight saving time, accumulating evidence reveals that the costs of shifting to daylight saving time cut across society. Although the negative outcomes are varied, the singular solution seems quite simple: Rather than change the clocks, we should change public policy. Many state legislatures have taken up this cause, with statehouses coast to coast reconsidering the annual practice.

As the research evidence is considered, other states could end up joining Arizona and Hawaii in abstaining from the annual daylight saving time madness. As we move toward that possibility, we may find it easier to save lives and money rather than chase the daylight.

This article was originally published on The Conversation. Read the original article.

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A Functioning Fake Womb

In a potential breakthrough for human babies born prematurely, scientists announced this year they’d successfully removed lamb fetuses from their mother’s wombs and raised them into healthy sheep. Their survival comes thanks to an artificial placenta — called a BioBag — created by researchers at the Children’s Hospital of Philadelphia.

The fake womb consists of a clear plastic bag filled with electrolytes. The lamb’s umbilical cord pulls in nutrients, and its heart pumps blood through an external oxygenator. The success caps a decades-long effort toward a working artificial placenta.

The BioBag could improve human infant mortality rates and lower the chances of a premature baby developing lung problems or cognitive disorders. But there are still challenges to scaling the device for human babies, which are much smaller than lambs. The scientists are also refining the electrolyte mix and studying how to connect human umbilical cords. They expect human trials in three to five years.

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Are Airplanes Really a Microbial Playground?

(credit: Matej Kastelic/Shutterstock)

Crying babies, chronic snorers — they’re the usual targets of our displeasure when we fly. But, the real villains of the sky might be germs.

Flyers are packed into a cramped metal tube for hours on end where movement is limited. It seems like a microbe’s playground. But research on the topic is a bit inconclusive, despite worrying cases involving SARS and an aggressive type of influenza. Studies suggest that caution is warranted, but researchers have so far had trouble saying exactly how air travel affects disease transmission. At the moment, public health guidelines state that anyone within two rows of an infected individual could be at risk, although other studies suggest otherwise.

Fly the Germy Skies?

Most recently, a team of researchers from Emory University and the Georgia Institute of Technology—funded by Boeing—conducted their own boots-on-the-plane study of infectious disease transmission aboard commercial aircraft. On 10 flights from Atlanta to the West Coast and back, they took swabbed samples of various surfaces and recorded how often passengers and crew members moved around. Pairing the data with models of air movement and microbe dispersion gave them an idea of just how far a potential pathogen might travel.

Their findings, published Monday in the Proceedings of the National Academy of Sciences, indicate that a sick neighbor is certainly something to worry about when flying. Those within a row of a sick person and within two seats to either side had an 80 percent chance of getting sick in their model, which used a fairly high assumed rate of transmission. The risk of infection drops off sharply after that, though. Those more than a few seats away had little to worry about. That’s even closer than the two row-minimum suggested by public health agencies.

A sick crew member, however, posed a little more danger. They move around the cabin more and have more contact with passengers, so the risk of transmission increases. Just one sick flight attendant infected almost five people on average in the researcher’s model. That’s a big number, but it does make some assumptions, the biggest of which is that sick crew members even come in to work. It’s more likely that they would just stay home.

Back Down to Earth

There are difficulties in modeling disease transmission rates on such a small scale like this, and this particular study wasn’t very big. They looked at just ten flights and the longest was only a bit over five hours. International flights can go for fifteen hours or longer, and involve much more movement on the part of passengers, something that could increase the risk of infection.

Their model also only looked at microbes that could be carried by droplets, which don’t travel very far. Viruses spread by smaller aerosol particles could circulate much longer and farther. This includes diseases like tuberculosis and measles. Air travel also involves extended periods of contact with other passengers at boarding gates, security checkpoints and elsewhere, and this could affect rates of transmission as well.

It’s also worth pointing out that we encounter similarly confined, crowded spaces during the course of our daily lives. Buses, movie theaters, workplaces and more pose the same sort of risks, though the authors don’t provide any measure of comparison here. Airplanes, do, however, travel long distances very quickly, something that can turn a local epidemic into a pandemic within days. That hasn’t happened yet, though scattered cases involving SARS and Ebola, among other diseases, have stoked worry.

Ultimately, a review of the scientific literature on the topic found moderate evidence that airplane cabins helped to spread influenza. This latest study doesn’t really change that, though it does reveal the danger that an infected crew member poses.

So, for flight attendants — and for all of us, really — if you’re sick, just stay home.

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This Optical Illusion Could Help to Diagnose Autism

(Credit: Turi et al., eLife, 7:e32399, 2018)

You probably see a cylinder when you look at the illusion above. But how our brains translate two intersecting sheets of moving dots into a 3D image reveals telling differences in visual perception that could perhaps help diagnose autism spectrum disorder.

It’s been shown that people with autism are better at picking out the details of complex images, at the cost of understanding what all those details mean when put together. This can mean seeing the trees, but not the forest, or the strokes of a paintbrush but not the subject of a painting. It’s a trait that’s supported by years of research, but it can be difficult to assess exactly how an individual perceives an image just by asking them questions. The cylinder illusion, applied here by a group of researchers from Italy and Australia, offers a more reliable way of telling what a subject is seeing.

Grow and Shrink

It comes down to the pupils. Our pupils are responsive to light, but they also widen and constrict in response to the notion of brightness or darkness, even if light levels remains the same. Here, the white dots are perceived as brighter, and the black dots as darker, and our pupils respond accordingly. It’s a way for the researchers to tell what parts of the illusion study participants are focusing on. They published their findings in March in the journal eLife.

The illusion itself relies on our brain’s assumptions of how a rotating cylinder behaves. The dots cross over each other just as marks on a transparent cylinder would, they even slow down at the edges to give the impression of curvature. The two colors give imply depth, though a closer look reveals that neither actually seems to be in front — some white dots cross over black dots, and some black over white. It allows us to reverse the cylinder’s apparent direction by focusing on one color over the other. Importantly for the researchers, the illusion is composed of both discrete details in the form of the dots, and a holistic image, in the form of the cylinder. Having both allows them to see which component their study participants favor.

They asked 50 adults, none of whom had autism, to watch the illusion, and while they were doing so, the researchers were watching them — their pupils at least. They wanted to see whether their pupils changed size rapidly throughout the experiment or stayed the same. If they changed size, it indicated that the participants were switching focus back and forth between the white and the black dots — i.e. they were focused on the details of the images. If their pupils stayed about the same, they were likely focused on both at once, meaning they saw the image as a whole. Crucially, both methods of perception produce the same cylinder illusion. But how they do so differs.


Before taking the test, the subjects all took the autism spectrum quotient, a self-reported questionnaire that measures various behaviors associated with autism. Higher scores indicate more correlation with autistic traits. When they paired scores on the test with measurements of pupil dilation and contraction, they saw that they were clearly related. Those whose pupils changed with greater frequency also reported more autistic traits. It was another validation of the theory that those with autism tend to focus on specific details as opposed to entire images.

Remember, none of the subjects had been formally diagnosed with autism, and none of their scores on the test indicated that they should be. In fact, the mean value of the test scores was about average. But, autism is a spectrum, and we all lie on it somewhere. Even in nominally average individuals, a tendency toward autistic traits was associated with a propensity to focus on details over holistic images. It adds further evidence that autism alters how we process visual information, and hints that it extends beyond those diagnosed with the disorder. The researchers say measuring changes in pupil size could potentially serve as another means of diagnosing autism.

The results are still a bit preliminary, so it’s too soon to draw definite conclusions based on their work. The surveys were all self-reported, for one thing, which can skew results a bit. And the study involved participants without autism, meaning that we’d need to see similar work in those with autism spectrum disorder to back up their findings.

But, with more research, the authors think their research could be used to perform assessments of those with autism who are non-verbal, which can happen in children. It would give doctors and teachers a way to get information from those who may not be able to communicate it themselves.

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