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Retired Canadian Astronaut & Author
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New research shows that sleep helps determine your personality

The quality and duration of your nightly ritual helps define who you are.

  • People who suffer from emotional instability tend to exhibit poor sleep duration, continuity, and subjective sleep quality.
  • Conscientious people report less variability in sleep duration and continuity.
  • The study suggests that how you sleep this week predicts your personality five years from now.

Sleep science is a rapidly growing field that has, time and again, proven how important sleeping is to every facet of our lives. Not getting enough sleep has been implicated in diseases of dementia, the ability to process memories, the removal of toxins from the brain, lost productivity (and associated costs), and workplace incivility—that's only the beginning of an extensive list.

The study above on being a rude co-worker hints at the notion that sleep informs your personality. Now new research, published in the European Journal of Personality, makes an even bolder claim: The quality of sleep you're getting this week will likely inform your personality five years from now.

According to Zlatan Križan and Garrett Hisler, both in the Department of Psychology at Iowa State University, of the five broad personality domains (agreeableness, conscientiousness, extraversion, neuroticism, and openness), two are greatly influenced by subjective sleep quality, while all five are in some manner determined by nightly habits.

The team identifies four critical aspects during each sleep cycle: duration, continuity, subjective quality, and architecture, or the "patterning of sleep state and biological activity."

Duration is important, with seven to nine hours being the sweet spot for most adults. How long you sleep is determined by a number of factors, including sleep debt, chronic sleep need, constraints such as work schedules, and personal preferences. Not everyone requires the same amount as everyone else, but knowing what you really need is important.

Continuity also plays a key role in regulating the physiological processes of your body. Ideally, you fall asleep easily, stay asleep, and wake up smoothly. Of course, this is not the case for many Americans, especially when checking your phone around bedtime (or worse, sleeping with it in your bed) negatively impacts your sleep.

Sleep quality is distinct in that it is self-reported. Importantly, the authors note, perception matters, as it is implicated in a number of mental health issues, including anxiety, depression, PTSD, bipolar disorder, and psychosis. Feeling unrested is a common factor in all of these.

Finally, sleep architecture deals with your ability to optimally cycle through the four states of sleep smoothly, including spending enough time in REM sleep. One sign of sleep deprivation, for example, is hanging out in non-REM mode; you never quite feel sated. For the purposes of this study, the duo did not focus on this aspect.

Joe Rogan - Sleep Expert on Insomnia

Križan and Hassler mined data from the Midlife in the United States Study, which provided a treasure trove of information that included week-long sleeping patterns and a rich assessment of personality traits. Of the 382 participants, 63 percent were female, with an age range between 34 and 82 years old. The most impacted personality traits were those displaying neuroticism (a tendency to experiencing negative emotions, aka emotional instability) and conscientiousness (an ability to display self-discipline; striving for achievement regardless of outside measures).

"In terms of intra-individual sleep variability, neuroticism predicted more variability in sleep duration, continuity, and subjective sleep quality, while conscientiousness predicted less variability in sleep duration and sleep continuity. Extraversion, agreeableness, and openness traits did not generally foreshadow behaviorally recoded sleep, only higher ratings of subjective quality."

Photo by Ute Grabowsky/Photothek via Getty Images

The authors note that most personality traits were impacted in some manner in typical reports of subjective sleep quality. The outliers were neuroticism, low conscientiousness, stress reaction, and alienation (such as hostility), all of which involved less sleep continuity. Variability and duration stood the test of time, however.

How you're sleeping now is likely how you've been doing it for a while—and likely how you'll be doing it in five years. As they report:

"The passage of time did little to weaken these links between personality and sleep; traits predicted sleep assessed more than five years later as well as sleep assessed only a few weeks later."

The link between personality and sleep seems to be a somewhat permanent fixture of the individual. On most every measure, the ability to control your behavior and emotions seems tied to better sleep. For those with troubles regulating their thoughts and emotions, the opposite holds true. These patterns continue throughout life, except if they are specifically addressed and changed.

This valuable addition to the growing literature on sleep science points to two important factors. Firstly, how you act and think consciously is embedded in your subconscious, which is in part regulated by sleep. Perhaps more importantly, if you want to change your patterns of behavior, diligently focusing on your nighttime ritual might be the catalyst for such change.

Data provided by this rich study summate what we already know: If you don't change your habits, you'll fall victim to them. Being malleable animals affords us the flexibility to integrate new patterns and the inner drive for making sure they stick. Increase your sleep duration and quality and behavioral shifts will occur.


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Neom, Saudi Arabia's $500 billion megacity, reaches its next phase

Construction of the $500 billion dollar tech city-state of the future is moving ahead.

Credit: Neom
Technology & Innovation
  • The futuristic megacity Neom is being built in Saudi Arabia.
  • The city will be fully automated, leading in health, education and quality of life.
  • It will feature an artificial moon, cloud seeding, robotic gladiators and flying taxis.
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Human brains remember certain words more easily than others

A study of the manner in which memory works turns up a surprising thing.

Image Point Fr / Shutterstock
Mind & Brain
  • Researchers have found that some basic words appear to be more memorable than others.
  • Some faces are also easier to commit to memory.
  • Scientists suggest that these words serve as semantic bridges when the brain is searching for a memory.

Cognitive psychologist Weizhen Xie (Zane) of the NIH's National Institute of Neurological Disorders and Stroke (NINDS) works with people who have intractable epilepsy, a form of the disorder that can't be controlled with medications. During research into the brain activity of patients, he and his colleagues discovered something odd about human memory: It appears that certain basic words are consistently more memorable than other basic words.

The research is published in Nature Human Behaviour.

An odd find

Image source: Tsekhmister/Shutterstock

Xie's team was re-analyzing memory tests of 30 epilepsy patients undertaken by Kareem Zaghloul of NINDS.

"Our goal is to find and eliminate the source of these harmful and debilitating seizures," Zaghloul said. "The monitoring period also provides a rare opportunity to record the neural activity that controls other parts of our lives. With the help of these patient volunteers we have been able to uncover some of the blueprints behind our memories."

Specifically, the participants were shown word pairs, such as "hand" and "apple." To better understand how the brain might remember such pairings, after a brief interval, participants were supplied one of the two words and asked to recall the other. Of the 300 words used in the tests, five of them proved to be five times more likely to be recalled: pig, tank, doll, pond, and door.

The scientists were perplexed that these words were so much more memorable than words like "cat," "street," "stair," "couch," and "cloud."

Intrigued, the researchers looked at a second data source from a word test taken by 2,623 healthy individuals via Amazon's Mechanical Turk and found essentially the same thing.

"We saw that some things — in this case, words — may be inherently easier for our brains to recall than others," Zaghloul said. That the Mechanical Turk results were so similar may "provide the strongest evidence to date that what we discovered about how the brain controls memory in this set of patients may also be true for people outside of the study."

Why understanding memory matters

person holding missing piece from human head puzzle

Image source: Orawan Pattarawimonchai/Shutterstock

"Our memories play a fundamental role in who we are and how our brains work," Xie said. "However, one of the biggest challenges of studying memory is that people often remember the same things in different ways, making it difficult for researchers to compare people's performances on memory tests." He added that the search for some kind of unified theory of memory has been going on for over a century.

If a comprehensive understanding of the way memory works can be developed, the researchers say that "we can predict what people should remember in advance and understand how our brains do this, then we might be able to develop better ways to evaluate someone's overall brain health."

Party chat

Image source: joob_in/Shutterstock

Xie's interest in this was piqued during a conversation with Wilma Bainbridge of University of Chicago at a Christmas party a couple of years ago. Bainbridge was, at the time, wrapping up a study of 1,000 volunteers that suggested certain faces are universally more memorable than others.

Bainbridge recalls, "Our exciting finding is that there are some images of people or places that are inherently memorable for all people, even though we have each seen different things in our lives. And if image memorability is so powerful, this means we can know in advance what people are likely to remember or forget."

spinning 3D model of a brain

Temporal lobes

Image source: Anatomography/Wikimedia

At first, the scientists suspected that the memorable words and faces were simply recalled more frequently and were thus easier to recall. They envisioned them as being akin to "highly trafficked spots connected to smaller spots representing the less memorable words." They developed a modeling program based on word frequencies found in books, new articles, and Wikipedia pages. Unfortunately, the model was unable to predict or duplicate the results they saw in their clinical experiments.

Eventually, the researchers came to suspect that the memorability of certain words was linked to the frequency with which the brain used them as semantic links between other memories, making them often-visited hubs in individuals's memory networks, and therefore places the brain jumped to early and often when retrieving memories. This idea was supported by observed activity in participants' anterior temporal lobe, a language center.

In epilepsy patients, these words were so frequently recalled that subjects often shouted them out even when they were incorrect responses to word-pair inquiries.

Seek, find

Modern search engines no longer simply look for raw words when resolving an inquiry: They also look for semantic — contextual and meaning — connections so that the results they present may better anticipate what it is you're looking for. Xie suggests something similar may be happening in the brain: "You know when you type words into a search engine, and it shows you a list of highly relevant guesses? It feels like the search engine is reading your mind. Well, our results suggest that the brains of the subjects in this study did something similar when they tried to recall a paired word, and we think that this may happen when we remember many of our past experiences."

He also notes that it may one day be possible to leverage individuals' apparently wired-in knowledge of their language as a fixed point against which to assess the health of their memory and brain.

Does conscious AI deserve rights?

If machines develop consciousness, or if we manage to give it to them, the human-robot dynamic will forever be different.

  • Does AI—and, more specifically, conscious AI—deserve moral rights? In this thought exploration, evolutionary biologist Richard Dawkins, ethics and tech professor Joanna Bryson, philosopher and cognitive scientist Susan Schneider, physicist Max Tegmark, philosopher Peter Singer, and bioethicist Glenn Cohen all weigh in on the question of AI rights.
  • Given the grave tragedy of slavery throughout human history, philosophers and technologists must answer this question ahead of technological development to avoid humanity creating a slave class of conscious beings.
  • One potential safeguard against that? Regulation. Once we define the context in which AI requires rights, the simplest solution may be to not build that thing.

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