Sitting still for long stretches of the day, muttering expletives under your breath, and staying up past midnight when you should be asleep – these are the kinds of behaviors most people quietly apologize for. They’re treated as signs of poor discipline, low class, or bad health choices. But a growing body of research suggests that for some people, these so-called bad habits track closely with something unexpected.
The connection isn’t folk wisdom or flattering self-mythology. It shows up in published studies, peer-reviewed journals, and large-scale cognitive datasets. Psychologists who study the relationship between personality, language, and brain function have repeatedly found that certain habits widely dismissed as character flaws are, in measurable ways, associated with higher cognitive ability. The three habits covered here are backed by real data – and the explanations behind each one are more specific than you might expect.
None of this means that staying up late makes you smarter or that swearing improves your vocabulary. The relationships are correlational, not causal. But they do suggest that what looks like a flaw from the outside can sometimes reflect something more interesting happening on the inside. Here’s what the science actually says about bad habits intelligent people often share.
1. Getting Bored Easily
Most people assume that easily bored individuals are simply impatient or unfocused. Researchers have proposed a different explanation: smarter people may get bored less easily in general, but when boredom does hit, it’s because they have longer attention spans and a higher threshold for what counts as genuine stimulation.
A 2016 study published in the Journal of Health Psychology found that people who prefer not to spend their time thinking tend to be more physically active than those who enjoy exercising their brains. Researchers tracked the physical activity of 60 undergraduate students, dividing them into two groups: those with a high “need for cognition” (NFC) and those with a low need. Todd McElroy, an associate professor of psychology at Florida Gulf Coast University and one of the study’s authors, describes NFC as an enjoyment of effortful, challenging mental tasks.
When researchers compared activity levels between the two groups, the difference was substantial: the low-NFC group moved significantly more every day during the week than the high-NFC group. The interpretation McElroy and his team offered was that high-cognition individuals stay absorbed in thought for longer stretches, and that mental engagement, not physical restlessness, is how they seek stimulation. McElroy acknowledged that thoughtful, intelligent people are often aware of the health risks of a sedentary lifestyle, but noted that if you’re engaged in thinking activities, you’re normally not moving. The practical upshot: if you find yourself easily bored by repetitive tasks, low-stakes small talk, or anything that doesn’t require real mental effort, that intolerance for empty stimulation may reflect a mind that needs more – not one that’s checked out.
2. Swearing More Than You Probably Should
A persistent cultural myth suggests that people who swear frequently do so because they lack the vocabulary to express themselves otherwise. But in 2015, researchers discovered that a robust knowledge of taboo language actually correlates with higher overall verbal ability, suggesting that a rich repertoire of curse words accompanies a well-stocked mental dictionary.
The most cited challenge to the “poverty of vocabulary” assumption comes from a series of studies by Kristin L. Jay of Marist College and Timothy B. Jay of the Massachusetts College of Liberal Arts, published in the journal Language Sciences in 2015. Participants were given a standard verbal fluency task – naming as many words beginning with a specific letter as they could in one minute. They were then given the same type of timed task using taboo words. The researchers confirmed the “fluency is fluency” theory: people who scored highest on the general language test also had higher swearing fluency, while those who performed poorly on verbal tasks showed poor results in both.
The overall finding across the Jay and Jay studies was that taboo fluency correlates positively with other measures of verbal fluency, suggesting that a large taboo vocabulary may be better understood as an indicator of healthy verbal abilities. Speakers who use taboo words understand their expressive content as well as the nuanced distinctions required to use certain terms appropriately – and the ability to make those distinctions reflects more linguistic knowledge, not less.
That doesn’t mean swearing freely in every setting is a display of intelligence – far from it. Knowing how and when to use these words is itself part of emotional intelligence. Knowing the words and deploying them with precision when the situation calls for it is different from using them as filler. The research doesn’t celebrate indiscriminate swearing; it challenges the lazy assumption that anyone who does it must have a limited vocabulary.
3. Staying Up Late – Bad Habits Intelligent People Often Share
A study investigating the effect of sleep on brain performance found a link between an individual’s preference for morning or evening activity and their brain function, suggesting that self-declared night owls generally tend to have higher cognitive scores. The size of the difference is what makes the finding striking.
Researchers at Imperial College London analyzed data from more than 26,000 people to find out how different aspects of sleep, including duration, patterns, and quality, affected mental sharpness and overall cognitive ability. Using data from the UK Biobank database, they examined UK adults who had completed a series of cognitive tests, including whether people described themselves as a “morning person” or an “evening person.” The study, “Sleep duration, chronotype, health and lifestyle factors affect cognition,” was published in BMJ Public Health in July 2024, with Dr. Raha West from the Department of Surgery and Cancer at Imperial College London as lead author.
Evening types scored about 13.5% higher than morning types in one cohort and 7.5% higher in a second. Intermediate sleepers – those who fall between the two extremes – also outperformed morning types, scoring around 10.6% and 6.3% higher respectively. The cognitive tests used in the study covered a range of brain functions, including fluid intelligence, reaction time, pairs matching, and prospective memory. Evening chronotypes showed better performance in information processing speed compared to intermediate and morning types, according to a 2025 review in Frontiers in Neuroscience that examined chronotype and executive functioning.
The Imperial College study also found that sleeping between 7 and 9 hours a night was optimal for brain function, boosting memory, reasoning, and processing speed. Sleeping fewer than 7 hours or more than 9 hours had a clearly detrimental effect on cognitive performance. So the advantage appears to lie in chronotype – the natural preference for evening activity – not in sleep deprivation. A night owl who gets a full night’s sleep, just shifted later, may be better positioned cognitively than an early riser who logs the same hours.
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What This Means for You
None of these habits are prescriptions. The research doesn’t suggest you should start swearing more, force yourself to stay up until 2 a.m., or deliberately avoid the gym. What it does suggest is that behaviors carrying a social stigma aren’t always what they appear to be, and that labeling them as flaws without understanding the underlying cognition can be too simple.
If you recognize yourself in any of these three patterns, the more useful question isn’t whether to change the habit but whether you’re getting the conditions right around it. A night owl who finally stops fighting their own biology and builds a sleep schedule around their natural chronotype, while still getting those 7 to 9 hours, may find they think more clearly than they ever did when trying to be a morning person. Someone who gets bored easily in meetings or low-stakes conversations may do better work when they protect uninterrupted blocks of time for the kind of deep, effortful thinking that genuinely engages them. And someone whose language is colorful but precise likely has more verbal range than the people quietly judging them. The science, at least, says so.
Disclaimer: This information is not intended to be a substitute for professional medical advice, diagnosis, or treatment and is for information only. Always seek the advice of your physician or another qualified health provider with any questions about your medical condition and/or current medication. Do not disregard professional medical advice or delay seeking advice or treatment because of something you have read here.
AI Disclaimer: This article was created with the assistance of AI tools and reviewed by a human editor.
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