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Can't stop unwanted thoughts? Poor sleep may be to blame, study says
The study sheds new light on the relationship between sleep and mental health.
- Poor sleep has been linked to many health problems, including diabetes, heart disease, obesity, depression, anxiety, suicidal thoughts and a shortened lifespan.
- A new study suggests that poor sleep also impairs the brain's ability to suppress unwanted thoughts.
- The researchers suspect this is because not getting enough sleep disrupts the brain's executive control functions.
Not getting enough sleep can wreak havoc on your mental health in ways that aren't immediately obvious. Studies have shown that poor sleep can disrupt the brain's ability to regulate cognitive and emotional regulation, exacerbating psychiatric conditions including anxiety, depression and bipolar disorder.
Now, new research suggests that poor sleep can also impair the brain's ability to suppress unwanted thoughts. The study was published October 15 in the journal Clinical Psychological Science.
The researchers knew from past research that poor sleep impairs cognitive functioning — especially executive control, which describes your ability to manage and regulate cognitive functions. Because blocking unwanted thoughts from your mind would be a cognitive function that falls into the executive control category, the researchers hypothesized that poor sleep would reduce the ability to suppress intrusive thoughts.
To test that idea, the researchers had two groups of participants take part in an overnight study. In the evening, all 60 participants were asked to memorize associations between pairs of images, each of which included a face and a scene that was rated either neutral or negative.
Both groups also learned a commonly used task in psychological experiments: the think/no-think paradigm. For the task, you're shown an image, and, depending on the visual cue, you're supposed to either think of something you've learned to associate with that image, or try to make your mind go blank.
Study procedures and tasks.
Credit: Harrington et al.
The participants were shown faces in either a green or red frame. The green frame indicated "think," meaning the participants should try to remember the image associated with that particular face. In contrast, red meant "no think," make your mind go blank — and if a thought pops up, try to get rid of it.
Then one group slept for about eight hours, while the other didn't sleep at all. In the morning, both groups completed the think/no-think task. The sleep-deprived group was far less able to keep intrusive thoughts out of their minds, despite the fact that both groups performed equally well the night before in a mock think/no-think task.
"Strikingly, the sleep-deprivation group suffered a proportional increase in intrusions of nearly 50% relative to the sleep group, revealing how deficient control may be a pathway to hyperaccessible thoughts," the researchers wrote.
As the experiment went along, both groups became increasingly successful at suppressing unwanted thoughts. But the sleep-deprived group was less successful. The results showed a similar effect on relapses of intrusive thoughts (which were prompted by showing the same visual cue multiple times during the experiment): Both groups became better at suppressing relapses over time, but the no-sleep group had a harder time blocking relapses.
"...sleep deprivation diminished the cumulative benefits of retrieval suppression for down-regulating subsequent intrusions," the researchers wrote. "Even after sleep-deprived participants initially gained control over unwanted memories and prevented them from intruding, they were consistently more susceptible to relapses when reminders were confronted again later compared with rested individuals."
In addition to having difficulty suppressing intrusive thoughts, the sleep-deprived group also seemed to be more negatively affected by those thoughts, based on subjective reports from the participants and skin-conductance responses recorded by the researchers.
Although the study didn't use brain imaging, the researchers noted that sleep deprivation may impair memory suppression by disrupting functional interactions between various parts of the brain, including "the [dorsolateral prefrontal cortex] (and possibly [medial prefrontal cortex]) and [medial temporal lobe] structures such as the hippocampus and amygdala during retrieval suppression, impairing inhibitory control over memory and affect, increasing intrusions, and decreasing affect suppression."
A potentially vicious cycle
The findings could shed light on how poor sleep interacts with psychiatric conditions, including major depressive disorder, schizophrenia, and obsessive compulsive disorder, to name a few.
"Insufficient sleep might increase memory intrusions while also nullifying the benefits of retrieval suppression for regulating affect," the researchers wrote. "The onset of intrusive thoughts and affective dysfunction following bouts of poor sleep could create a vicious cycle whereby upsetting intrusions and emotional distress exacerbate sleep problems, inhibiting the sleep needed to support recovery."
Fortunately, evidence suggests people can get better at suppressing intrusive thoughts. For example, a 2018 study found that college students who reported having experienced high levels of trauma were better at suppressing unwanted thoughts compared to students who had led relatively trauma-free lives.
"...given proper training, individuals can learn to better manage intrusive experiences, and are broadly consistent with the view that moderate adversity can foster resilience later in life," wrote the researchers behind the 2018 study.
The team behind the recent study similarly noted that people with major depressive disorder might benefit from interventions where they learned strategies for suppressing unwanted thoughts.
How to get better sleep
No matter your ability to suppress unwanted thoughts, getting good sleep (seven to eight hours for most adults) is one of the most consequential health decisions you can make. Harvard Medical School offers eight tips for getting better sleep:
- Exercise at some point during the day.
- Reserve your bed for sleep and sex—not work or TV.
- Keep the bedroom comfortable.
- Start a sleep ritual.
- Have a bedtime snack—but not too much.
- Avoid alcohol and chocolate before bed.
- Wind down before going to bed.
- See your doctor about what's keeping you up at night.
- Scientists finally know why sleep deprivation leads to mental ... ›
- Lack of sleep leads to the shutdown of production of essential brain ... ›
- Childhood sleeping problems signal mental disorders later - Big Think ›
Why mega-eruptions like the ones that covered North America in ash are the least of your worries.
- The supervolcano under Yellowstone produced three massive eruptions over the past few million years.
- Each eruption covered much of what is now the western United States in an ash layer several feet deep.
- The last eruption was 640,000 years ago, but that doesn't mean the next eruption is overdue.
The end of the world as we know it
Panoramic view of Yellowstone National Park
Image: Heinrich Berann for the National Park Service – public domain
Of the many freak ways to shuffle off this mortal coil – lightning strikes, shark bites, falling pianos – here's one you can safely scratch off your worry list: an outbreak of the Yellowstone supervolcano.
As the map below shows, previous eruptions at Yellowstone were so massive that the ash fall covered most of what is now the western United States. A similar event today would not only claim countless lives directly, but also create enough subsidiary disruption to kill off global civilisation as we know it. A relatively recent eruption of the Toba supervolcano in Indonesia may have come close to killing off the human species (see further below).
However, just because a scenario is grim does not mean that it is likely (insert topical political joke here). In this case, the doom mongers claiming an eruption is 'overdue' are wrong. Yellowstone is not a library book or an oil change. Just because the previous mega-eruption happened long ago doesn't mean the next one is imminent.
Ash beds of North America
Ash beds deposited by major volcanic eruptions in North America.
Image: USGS – public domain
This map shows the location of the Yellowstone plateau and the ash beds deposited by its three most recent major outbreaks, plus two other eruptions – one similarly massive, the other the most recent one in North America.
The Huckleberry Ridge eruption occurred 2.1 million years ago. It ejected 2,450 km3 (588 cubic miles) of material, making it the largest known eruption in Yellowstone's history and in fact the largest eruption in North America in the past few million years.
This is the oldest of the three most recent caldera-forming eruptions of the Yellowstone hotspot. It created the Island Park Caldera, which lies partially in Yellowstone National Park, Wyoming and westward into Idaho. Ash from this eruption covered an area from southern California to North Dakota, and southern Idaho to northern Texas.
About 1.3 million years ago, the Mesa Falls eruption ejected 280 km3 (67 cubic miles) of material and created the Henry's Fork Caldera, located in Idaho, west of Yellowstone.
It was the smallest of the three major Yellowstone eruptions, both in terms of material ejected and area covered: 'only' most of present-day Wyoming, Colorado, Kansas and Nebraska, and about half of South Dakota.
The Lava Creek eruption was the most recent major eruption of Yellowstone: about 640,000 years ago. It was the second-largest eruption in North America in the past few million years, creating the Yellowstone Caldera.
It ejected only about 1,000 km3 (240 cubic miles) of material, i.e. less than half of the Huckleberry Ridge eruption. However, its debris is spread out over a significantly wider area: basically, Huckleberry Ridge plus larger slices of both Canada and Mexico, plus most of Texas, Louisiana, Arkansas, and Missouri.
This eruption occurred about 760,000 years ago. It was centered on southern California, where it created the Long Valley Caldera, and spewed out 580 km3 (139 cubic miles) of material. This makes it North America's third-largest eruption of the past few million years.
The material ejected by this eruption is known as the Bishop ash bed, and covers the central and western parts of the Lava Creek ash bed.
Mount St Helens
The eruption of Mount St Helens in 1980 was the deadliest and most destructive volcanic event in U.S. history: it created a mile-wide crater, killed 57 people and created economic damage in the neighborhood of $1 billion.
Yet by Yellowstone standards, it was tiny: Mount St Helens only ejected 0.25 km3 (0.06 cubic miles) of material, most of the ash settling in a relatively narrow band across Washington State and Idaho. By comparison, the Lava Creek eruption left a large swathe of North America in up to two metres of debris.
The difference between quakes and faults
The volume of dense rock equivalent (DRE) ejected by the Huckleberry Ridge event dwarfs all other North American eruptions. It is itself overshadowed by the DRE ejected at the most recent eruption at Toba (present-day Indonesia). This was one of the largest known eruptions ever and a relatively recent one: only 75,000 years ago. It is thought to have caused a global volcanic winter which lasted up to a decade and may be responsible for the bottleneck in human evolution: around that time, the total human population suddenly and drastically plummeted to between 1,000 and 10,000 breeding pairs.
Image: USGS – public domain
So, what are the chances of something that massive happening anytime soon? The aforementioned mongers of doom often claim that major eruptions occur at intervals of 600,000 years and point out that the last one was 640,000 years ago. Except that (a) the first interval was about 200,000 years longer, (b) two intervals is not a lot to base a prediction on, and (c) those intervals don't really mean anything anyway. Not in the case of volcanic eruptions, at least.
Earthquakes can be 'overdue' because the stress on fault lines is built up consistently over long periods, which means quakes can be predicted with a relative degree of accuracy. But this is not how volcanoes behave. They do not accumulate magma at constant rates. And the subterranean pressure that causes the magma to erupt does not follow a schedule.
What's more, previous super-eruptions do not necessarily imply future ones. Scientists are not convinced that there ever will be another big eruption at Yellowstone. Smaller eruptions, however, are much likelier. Since the Lava Creek eruption, there have been about 30 smaller outbreaks at Yellowstone, the last lava flow being about 70,000 years ago.
As for the immediate future (give or take a century): the magma chamber beneath Yellowstone is only 5 percent to 15 percent molten. Most scientists agree that is as un-alarming as it sounds. And that its statistically more relevant to worry about death by lightning, shark, or piano.
Strange Maps #1041
Got a strange map? Let me know at firstname.lastname@example.org.
The pandemic has many people questioning whether they ever want to go back to the office.
If one thing is clear about remote work, it's this: Many people prefer it and don't want their bosses to take it away.
When the pandemic forced office employees into lockdown and cut them off from spending in-person time with their colleagues, they almost immediately realized that they favor remote work over their traditional office routines and norms.
As remote workers of all ages contemplate their futures – and as some offices and schools start to reopen – many Americans are asking hard questions about whether they wish to return to their old lives, and what they're willing to sacrifice or endure in the years to come.
Even before the pandemic, there were people asking whether office life jibed with their aspirations.
We spent years studying “digital nomads" – workers who had left behind their homes, cities and most of their possessions to embark on what they call “location independent" lives. Our research taught us several important lessons about the conditions that push workers away from offices and major metropolitan areas, pulling them toward new lifestyles.
Legions of people now have the chance to reinvent their relationship to their work in much the same way.
Big-city bait and switch
Most digital nomads started out excited to work in career-track jobs for prestigious employers. Moving to cities like New York and London, they wanted to spend their free time meeting new people, going to museums and trying out new restaurants.
But then came the burnout.
Although these cities certainly host institutions that can inspire creativity and cultivate new relationships, digital nomads rarely had time to take advantage of them. Instead, high cost of living, time constraints and work demands contributed to an oppressive culture of materialism and workaholism.
Pauline, 28, who worked in advertising helping large corporate clients to develop brand identities through music, likened city life for professionals in her peer group to a “hamster wheel." (The names used in this article are pseudonyms, as required by research protocol.)
“The thing about New York is it's kind of like the battle of the busiest," she said. “It's like, 'Oh, you're so busy? No, I'm so busy.'"
Most of the digital nomads we studied had been lured into what urbanist Richard Florida termed “creative class" jobs – positions in design, tech, marketing and entertainment. They assumed this work would prove fulfilling enough to offset what they sacrificed in terms of time spent on social and creative pursuits.
Yet these digital nomads told us that their jobs were far less interesting and creative than they had been led to expect. Worse, their employers continued to demand that they be “all in" for work – and accept the controlling aspects of office life without providing the development, mentorship or meaningful work they felt they had been promised. As they looked to the future, they saw only more of the same.
Ellie, 33, a former business journalist who is now a freelance writer and entrepreneur, told us: “A lot of people don't have positive role models at work, so then it's sort of like 'Why am I climbing the ladder to try and get this job? This doesn't seem like a good way to spend the next twenty years.'"
By their late 20s to early 30s, digital nomads were actively researching ways to leave their career-track jobs in top-tier global cities.
Looking for a fresh start
Although they left some of the world's most glamorous cities, the digital nomads we studied were not homesteaders working from the wilderness; they needed access to the conveniences of contemporary life in order to be productive. Looking abroad, they quickly learned that places like Bali in Indonesia, and Chiang Mai in Thailand had the necessary infrastructure to support them at a fraction of the cost of their former lives.
With more and more companies now offering employees the choice to work remotely, there's no reason to think digital nomads have to travel to southeast Asia – or even leave the United States – to transform their work lives.
During the pandemic, some people have already migrated away from the nation's most expensive real estate markets to smaller cities and towns to be closer to nature or family. Many of these places still possess vibrant local cultures. As commutes to work disappear from daily life, such moves could leave remote workers with more available income and more free time.
The digital nomads we studied often used savings in time and money to try new things, like exploring side hustles. One recent study even found, somewhat paradoxically, that the sense of empowerment that came from embarking on a side hustle actually improved performance in workers' primary jobs.
The future of work, while not entirely remote, will undoubtedly offer more remote options to many more workers. Although some business leaders are still reluctant to accept their employees' desire to leave the office behind, local governments are embracing the trend, with several U.S. cities and states – along with countries around the world – developing plans to attract remote workers.
This migration, whether domestic or international, has the potential to enrich communities and cultivate more satisfying work lives.
The potential of CRISPR technology is incredible, but the threats are too serious to ignore.
- CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) is a revolutionary technology that gives scientists the ability to alter DNA. On the one hand, this tool could mean the elimination of certain diseases. On the other, there are concerns (both ethical and practical) about its misuse and the yet-unknown consequences of such experimentation.
- "The technique could be misused in horrible ways," says counter-terrorism expert Richard A. Clarke. Clarke lists biological weapons as one of the potential threats, "Threats for which we don't have any known antidote." CRISPR co-inventor, biochemist Jennifer Doudna, echos the concern, recounting a nightmare involving the technology, eugenics, and a meeting with Adolf Hitler.
- Should this kind of tool even exist? Do the positives outweigh the potential dangers? How could something like this ever be regulated, and should it be? These questions and more are considered by Doudna, Clarke, evolutionary biologist Richard Dawkins, psychologist Steven Pinker, and physician Siddhartha Mukherjee.
Measuring a person's movements and poses, smart clothes could be used for athletic training, rehabilitation, or health-monitoring.