Are you tired of being labeled as either an early bird or a night owl? It turns out these categories might be oversimplifying the complex world of sleep patterns. Scientists are now diving deeper into chronotypes—the natural times when individuals feel most inclined to sleep, wake, and function optimally. But here's where it gets controversial: the traditional view that night owls are unhealthy and early birds are paragons of virtue is being challenged.
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If you’ve ever struggled to fit into the early bird mold as a night owl, there’s good news. Researchers are uncovering a more nuanced understanding of how sleep patterns influence health and behavior. Chronotypes, which describe these natural tendencies, were once linked to health outcomes—late-night types were often associated with issues like heart disease and depression. But the science wasn’t consistent, and now a groundbreaking Canadian-led study is reshaping our understanding.
Published in Nature Communications (https://www.nature.com/articles/s41467-025-66784-8), this study of over 27,000 U.K. adults combines brain imaging, computer science, questionnaires, cognitive tests, and medical reviews to paint a detailed picture of sleep patterns. The key takeaway? Lumping people into just two groups—early and late risers—is far too simplistic, says Le Zhou, the study’s lead author and a PhD student in neuroscience at McGill University.
‘People assume night owls have unhealthy habits and early birds are healthier,’ Zhou explains. ‘But our study shows it’s not that straightforward.’
Instead of broad categories, the research identifies five distinct subtypes within night owls and early birds, each tied to specific behaviors and health outcomes. Among night owls:
- Cognitive high-achievers outperformed others in tests but struggled with emotional regulation, often exhibiting impulsive behaviors like smoking or drinking.
- Less active types showed no cognitive advantages, got less physical activity, and faced higher risks of cardiovascular issues and depression.
- Energetic socializers loved working out and socializing, tended to be male, and consumed more alcohol, with higher average testosterone levels.
For early birds:
- Stable lifestylers had fewer health problems, rarely smoked or drank, and enjoyed club activities.
- Depression-prone types had schedules more closely linked to depression and showed hormone patterns typical of females, like lower testosterone.
While the study doesn’t pinpoint the most vulnerable group, Zhou suggests night owls focus on increasing physical activity and managing anxiety rather than forcing a sleep schedule change. Early birds struggling with issues might benefit from stronger social support.
And this is the part most people miss: Scientists theorize that these chronotypes evolved to help early humans stay vigilant against nighttime threats by staggering sleep times. But does this ancient adaptation still serve us today?
Digging deeper, the study relied on self-reported chronotypes, which University of Ottawa professor Rébecca Robillard notes as a limitation. ‘The findings would be stronger with biological measures like hormone or temperature changes,’ she says, predicting researchers will incorporate these soon.
However, Dr. Michael Mak from the Centre for Addiction and Mental Health in Toronto highlights a strength: the findings were validated against a U.S. database of younger individuals, boosting confidence in the results. ‘We’re looking at broad trends, but individual differences are likely much larger,’ Mak explains.
Even without knowing your exact chronotype, there’s a simple strategy, says Jessica Chalekas, a sleep anthropology expert at Brunel University. ‘Take a couple of weeks to observe your patterns. When do you feel most functional?’
So, what does this mean for our understanding of chronotypes? Robillard praises the study for advancing the link between chronotypes and brain patterns. As a clinical sleep researcher, she advises tailoring daily routines to align with your natural chronotype. For late risers, this could mean using light exposure to gently shift your internal clock earlier. ‘The sun is your ally,’ she says, recommending morning coffee breaks outdoors, even on cloudy days.
With Canada’s springtime clock change approaching, Robillard points out that late risers are more affected by time shifts—one reason she advocates abolishing daylight saving time (https://www.cbc.ca/listen/cbc-podcasts/410-the-dose/episode/16178560-why-does-the-time-change-mess-with-my-sleep-and-what-can-i-do-about-it). She also stresses the importance of a consistent sleep schedule, warning against weekend sleep-ins that confuse your body’s internal clock.
Of course, there are limits to changing your chronotype, notes sleep specialist Dr. Michael Mak. ‘These changes won’t be permanent or eliminate health risks,’ he cautions.
Night owls, take heart: you’re not lazy. Dr. Maha Alattar, a neurology professor and sleep specialist, reassures patients that their late chronotype is simply a mismatch with societal schedules. ‘It’s your responsibility to cultivate healthy evening and morning habits,’ she says.
Chronotypes can also become dysfunctional in nursing homes or dementia patients, where brain cells no longer respond to sunlight cues. ‘Respect your biology for sleep and wakefulness,’ Alattar advises. ‘A good night’s sleep is an investment in your health.’
Thought-provoking question for you: Should society rethink work and school schedules to accommodate diverse chronotypes, or is it up to individuals to adapt? Share your thoughts in the comments—let’s spark a conversation!
