Are you an early bird or a night owl? Perhaps you've always thought of yourself as one or the other, but scientists are now moving beyond these simple groupings. A recent study has revealed a more nuanced understanding of sleep patterns and their impact on health and behavior.
The research, led by Le Zhou from McGill University, found that categorizing people into just two groups - late and early risers - is too simplistic. Instead, they identified five distinct subtypes among self-described night owls and early birds, each tied to specific patterns of behavior and health.
The study combined extensive brain imaging with computer science and questionnaires, cognitive tests, and medical chart reviews.
Among the findings:
- Night owls who outperformed in cognitive tests but struggled with emotional regulation, often showing impulsive behaviors or addictive habits.
- Night owls who didn't perform as well cognitively and had less physical activity due to their schedule, with higher cardiovascular risks and depression levels.
- Energetic night owls who loved working out and socializing, tended to be mainly male and drank more alcohol, with high testosterone levels on average.
For early birds:
- Those with stable lifestyles, fewer risk-taking behaviors, and who rarely smoked or drank, enjoyed club activities, and had the fewest health problems.
- Early birds whose schedules were more closely tied to depression, with patterns typical of female hormones like lower testosterone.
While the study didn't quantify which group is most vulnerable, Zhou suggested that night owls get more physical activity and find healthier ways to manage anxiety instead of trying to change sleep timing. For the high-performance group, he advised following their natural rhythm to manage impulsivity and substance use. Early risers experiencing issues might benefit from enhancing social support.
Scientists suspect that these different chronotypes evolved so groups of early human ancestors could stagger their sleep times across the night to stay vigilant against night-time threats like predators.
Looking deeper into the study, University of Ottawa professor Rébecca Robillard noted a drawback: people self-identified their chronotype with a questionnaire. She suggested that multiple biological measures like hormonal or temperature changes would make the findings more robust, which she believes the researchers will do soon.
Despite this, Dr. Michael Mak of the Centre for Addiction and Mental Health in Toronto noted that a strength of the study was its validation against another database of younger people in the U.S., increasing scientists' confidence in their findings.
Even if you don't know your exact chronotype, Jessica Chalekas, an expert in the sociocultural anthropology of sleep, recommends taking a week or two to check in with yourself and notice your patterns. When do you feel your best?
What does this all mean for understanding chronotypes? Robillard called the study impressive for pushing the bar on associations between chronotypes and brain patterns. As director of a clinical sleep research unit, she suggested that people adapt their daily schedule to facilitate their chronotype's thriving in their daily routine.
For late risers, that could include light exposure to push the internal rhythm to an earlier phase. The sun is a strong ally here, so she recommends taking a morning coffee break outside, even on cloudy days.
As much of Canada approaches the spring clock change, Robillard noted that late risers are more affected by time change, which is one reason she advocates abolishing daylight saving time. Recent models suggest that the consistency of one's sleep schedule also matters, meaning yo-yoing between early wakes and late sleeps isn't ideal.
Of course, there are limits to trying to change one's chronotype, said Mak, a sleep medicine specialist. The changes won't be permanent and probably won't obviate health risks.
Night owls are not lazy, counters Dr. Maha Alattar, an associate professor of neurology at Virginia Commonwealth University and a sleep specialist. 'You just have this circadian rhythm that's not in line with the world schedule. And there's nothing wrong with you, but it is your obligation to make sure that you have good habits in the evening and in the morning.'
At the end of the day, we all need to rest. Respect your biology for sleep and wakefulness, Alattar said. 'A good night's sleep is an investment in your health.'
