This finding resulted from an investigation into a group of cells that had previously been recorded aggregating around the damaged portion of lab mice brains, following injections and similar sources of injury. The researchers behind those earlier observations didn’t know what the cells were, but a masters student intern at the Max Planck Institute of Psychiatry named Clemens Ries decided to look into the matter and discovered that they were oligodendrocyte progenitor cells, or OPCs. These cells mature into oligodendrocytes, which produce the myelin sheath that surrounds and protects the axons that allow neurons to communicate with each other in our brains.

This subject eventually became the topic of Ries’ doctoral thesis, and his later work showed that about a third of the OPCs surrounding brain injuries activate corticotropin-releasing hormone (CRH), which is a hormone that helps regulate the body’s stress response. This was a new finding: researchers didn’t realize OPCs could produce neuropeptides like CRH.

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The hypothalamic-pituitary-adrenal, or HPA axis is a neuroendocrine system that responds to stress. Humans experience a rise in cortisol when we wake up each morning (this is called the cortisol awakening response, or CAR), and that initial level of cortisol, and the subsequent rise after waking, are markers of how active our HPA axis is.

Studies have generally shown that a person’s level of subjective stress lines up with their cortisol level (more cortisol equals higher perceived stress), and again, more cortisol means a more active HPA axis. So anything that dysregulates our HPA axis might also impact our perceived level of stress.

Cortisol is useful for all sorts of things: it helps us fight infection, maintain blood pressure, and regulate metabolism and blood sugar. So it’s not just a stress hormone, it helps with overall body functionality.

The researchers in this study were looking at the CAR of their subjects, measuring that increase in cortisol levels by checking cortisol immediately when they awoke, and then checking again 30 minutes later—subtracting the latter from the former to get the rate of increase.

The CAR remained steady between cannabis user and non-user groups, but the researchers did note a marked difference in cortisol starting levels between heavy users and everyone else: these heavy users already had more cortisol in their bodies to begin with, when they woke up.

The numbers are suggestive of a correlation between heavy cannabis use and this increased level of waking cortisol, but there’s also a chance the relationship goes the other way, and that people who have naturally higher levels of cortisol in the morning are heavier users of cannabis, maybe using drug to help calm their nerves.

There’s also a chance that increased waking cortisol levels points to cannabis-use issues (including a disrupted HPA axis), and it could thus become a reliable means of determining who may benefit from some kind of intervention or alternative means of coping with stress, though further research is necessary to determine what leads to what.

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This mechanism, which they call “behavioral timescale synaptic plasticity,” or BTSP, manifests as an electrical charge that impacts multiple neurons simultaneously. This allows the brain to quickly learn something new after just one occurrence, which is distinct from other neuroplasticity mechanisms that reshape the brain after multiple encounters with the same experience.

Synaptic plasticity is a relatively new concept, but is now broadly accepted by the neurological community. And it says, in essence, that the connections between our neurons can change over time, which is why someone who loses an arm or whose eyesight deteriorates can compensate for those bodily and sensory changes, their brains rewiring to account for their adjusted physical capability and visual input. It’s also why we can continue to change as people well into adulthood.

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Ultra-processed foods (UPFs) have been under a microscope recently, as a growing body of research has hinted that this category of foods can lead to overeating, weight-gain, and a higher risk of developing heart disease and diabetes.

As the label implies, UPFs are foods that have been heavily processed and include with one or more ingredients that wouldn’t typically be found in a home kitchen, including emulsifiers like hydrogenated oils, artificial colors and flavors, and sweeteners like high fructose corn syrup. These ingredients are common in food products found on shelves, and the incentives of the consumer food market—needing to make things shelf-stable, appealing, and ideally addictive (so customers keep coming back)—are why these ingredients are so common in consumer food products these days.

While these ingredients are found in foods globally, they’re more common in some places than others. More than half the calories the average American adult consumes are from ultra-processed foods, for instance. So this isn’t a niche category, this is the dominant food dynamic in some places. And that’s part of why UPFs have been such a big focus for researchers, of late. It seems like their prominence and the slew of health issues people in places like the US face might be correlated.

That correlation is still not definitive, but we are seeing more and more data backing it, and we’re learning more about what these foods seem to do to us, beyond our body composition and overall health.

That new study shows that subjects who got about 41% of their daily energy from UPFs (which is close to the national average for adults in Australia, which is 42%) saw a measurable drop in their ability to focus.

What’s more, they saw a measurable drop for every 10% increase in their consumption of ultra-processed foods. So the more chips and soda and ready-made meals they ate, the less they were capable of focusing. And interestingly, this held up even for people who consumed a generally healthy diet: if they deviated from their healthy diet to snack, their ability to focus still suffered at about this rate.

Eating more UPFs was also linked to an increase in dementia risk factors in this study, including high blood pressure and obesity, which reinforces the findings of other studies.

The focus-related findings are the more surprising data points, though, as UPFs have been linked to all sorts of health issues (including dementia) in previous research, but the link between unhealthy foods and focus is (so far, at least) less well-tread territory.

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There’s a bunch of data showing that there are more divorces in heterosexual marriages in which the woman makes more money than the man (separations are 36% more likely, in fact). And this study tested seven long-suspected explanations for this higher rate of breakups.

One of the most commonly cited explanations is that culture and gender norms favor male breadwinners, and that society will therefore punish couples in which the woman makes more money than the man in various ways, which strains the relationship.

It’s also been asserted that women with degrees increasingly face a marriage market in which there’s a shortage of similarly educated men, that women who have their own resources are just freer to leave not-great relationships than women who don’t have that kind of economic flexibility, or that women tend to ramp up their work schedule before an anticipated breakup (to ensure they can support themselves, post-separation), so there could be reverse-causation in the numbers: it looks like women making more money leads to divorces, but in reality the lead-up to a divorce nudges women to make more money so that they’re economically okay, post-split.

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This study was based on survey responses from nearly 2,800 Australians who participated in the country’s annual National Climate Action Survey at least twice.

The researchers asked these subjects about behaviors like recycling, taking public transit, and eating a greener diet, along with questions about their participation in collective climate actions like supporting climate-friendly government policies and attending relevant demonstrations.

Past research on this subject has been mixed, but there’s been widespread suggestion that engaging in individual behaviors like recycling might nudge a person to be greener in their collective actions as well: maybe someone who comes to self-define as the sort of person who takes the climate seriously by engaging in such habits will then go on to engage in large-scale efforts, like those related to climate policy.

Others have contended that these small-scale actions distract from the larger, actually impactful activities that we might otherwise focus on. Recycling is seldom terribly impactful because of the nature of most recycling systems, even though it might make us feel like we’re doing something meaningful. If we recycle, though, it may be easier to justify not voting for more public transit because we feel like we’re already doing our part. That’s the opposing theory, at least.

This study was the first to look at the changes in people’s behaviors regarding climate action over time, and it found that a change to someone’s personal actions—recycling habits, for instance—did not correlate with taking more collective action. Taking personal actions also didn’t seem to get in the way of engaging in collective, large-scale climate-related activities.

These findings suggest that a person’s level of support for climate-related efforts, at all scales, are kind of baked into a person’s beliefs and behaviors: someone who recycles is more likely to go to climate protests, and someone who doesn’t recycle is less likely to attend the same.

Smaller actions don’t seem to nudge anyone toward larger collective actions, but they also don’t use up all of a person’s climate-related enthusiasm.

These findings support the assertion that those earlier debates are warrantless, but they do raise a new question for people and organizations hoping to sway populations toward climate action: if small behavioral nudges don’t shift attitudes in favor of pursuing these sorts of solutions, what might?

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The researchers had 23 dual-fluent Spanish-English bilingual people complete a phrase-completion task that involved being shown a noun, hearing a social cue, and then having to speak a version of that noun based on a spoken cue (repeating the word as-is, or speaking the singular or pluralized version of it). The word prompts flipped between languages and varied the changes that were required to come up with the correct, final word.

While they were participating in this task, subjects’ brain activity was tracked using magnetoencephalography (MEG) at a millisecond resolution, allowing the researchers to track active neurons, which in turn allowed them to see which parts of the brain were being activated, when.

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Nonetheless, those without children continued to rank higher in happiness metrics than their children-having peers, and notably, adults who were married tended to rank higher in happiness than their unmarried peers, whether or not children were involved.

That long period of consistent findings is why the results of a recent study looking at the same thing are so surprising.

A big caveat up front is that the group that flagged this change (the Institute of Family Studies) has a distinct pro-family bias. The data comes from the less-biased US General Social Survey, so it’s government data, not numbers the Institute collected. But that bias is still worth noting, and it’s thus worth taking this seeming upending of happiness trends with a grain of salt.

That said, for women, married mothers ranked highest for happiness in this new survey (40% saying they’re “very happy”), with childless wives (women who are married but don’t have children) ranking second (25%). Childless and single women came in third, and single mothers ranked last in terms of happiness. Unhappiness rankings mirrored the happiness numbers, with relatively few (13%) married mothers saying they’re “not too happy,” while childless, single women came in first (25%).

The same was generally true for men, with married fathers ranking as the happiest (35% very happy, 16% not too happy) and single fathers as the least happy (12% very happy, 37% not too happy).

There’s no clear reason for this seeming reversal of happiness rankings for married, child-having couples. One popular theory is that because fertility levels have dropped so precipitously (including in the US, where this survey was conducted), the pressure to have children, even as a married couple, is a lot lower than it used to be. Consequently, if you don’t want kids, you probably won’t have them, and the people who are having kids probably wanted to. That means those who have kids will be more likely to be happy, because they’re in the situation they wanted, rather than being in a situation they were pressured into (by society or healthcare realities).

The findings from a recent German study seem to support this assertion, but we really don’t know for certain what’s leading to this seeming change in overall life satisfaction in these groups. And again, we also can’t be 100% certain this is an actual trend, as it could be a blip in the data, and it could be that the entity using the data is tweaking the findings somehow to match their worldview.

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The premise of this study is that we parse information about the world through the lens of our internal state. If we’re feeling anxious we might respond to someone’s comment about what we’re wearing differently than if we’re feeling confident.

That internal state is influenced by all sorts of variables, including the current state of our parasympathetic nervous system, which is responsible for managing our bodily functions and shifting us into “rest and digest” or “feed and breed” modes (or somewhere in between).

A spike in parasympathetic activity usually occurs after eating or engaging in some kind of calming activity (like reading or meditating), and typically lowers our heart rate, increases the volume of acid in our stomach to aid with digestion, and constricts our airway muscles so that it takes less effort to restfully breathe.

Slowing our breathing has been previously shown to increase parasympathetic activity, helping us shift into that calm, more relaxed internal state.

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The researchers used EEG recordings from adults with normal levels of hearing and had them listen to two competing speech streams simultaneously. They were tasked with switching their attention between the two competing speech streams every 15 to 30 seconds, and their neural tracking (what their brains were focused on at any given moment) was assessed using Temporal Response Functions, which are mathematical models that help quantify how the brain processes audio inputs, including, in this case, when the brain has switched from processing one input to another.

What they found is that there’s a momentary handoff mode during which the brain is still listening to the conversational stream it has been actively tracking, but also starts listening to the stream it’s about to switch over to, creating a sort of informational buffer that contains information from the new stream while still processing information from the current stream.

There’s a fair amount of variability between people, in terms of their dual-stream buffer capacity, and this might shape a person’s natural propensity toward being able to navigate complex social situations and noisy environments, as their brains may be more or less capable of quickly switching between streams of info-laden sound.

This also gestures at a possible source of the exhaustion some older and hard of hearing people feel in noisy situations: when this buffering system is strained, we’re forced to expend more effort (consume more energy) to distinguish one audio stream from another. So if our hearing is anything but optimal, there’s a chance this buffer system won’t work at full capacity, and every complex conversation or noisy environment will require more concentrated focus (and thus, require more effort) to navigate.