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What You Need to Know About Your Chronotype

Why there’s much more to chronotype than being a morning or night person.

Bruce Mars/Unsplash
Source: Bruce Mars/Unsplash

Why is knowing your individual chronotype so important? It’s a roadmap for optimizing nearly every aspect of your daily life. Our daily circadian rhythms regulate sleep, hunger, metabolism, immunity, cognition, desire, creativity, sociability, and nearly all of your body’s physiological activity, rising and falling throughout the 24-hour day, each playing their part in the incredibly complex orchestra of your body’s daily functioning.

Understanding the timing of our biological rhythms tells us the optimal time to eat, sleep and exercise, how to organize our daily workflow, when to have sex (for maximum pleasure), when to argue with our partner (and when not to), when to take medicine and supplements, when to brainstorm a new idea and when to pitch that idea in a meeting… when to do just about everything. It’s the difference between working with your body’s biology, and fighting against it—which all too many of us do, when we live our lives out of sync with our circadian rhythms.

Science and medicine haven’t always taken into account the importance of circadian timing—the when of daily life. Far from it. We’re still at the dawn of using our bodies’ daily rhythms to live longer, healthier, happier, more productive, and better-rested lives.

Our understanding of chronotype is still relatively new, but we’ve learned a tremendous amount in the past 50 years or so. Today I thought we’d take a little step back and look at how chronotype theories have evolved, and why chronotypes had to move beyond morning, evening, and in-between types—and beyond sleep itself.

The Two Types: Morning and Evening

Scientists began observing evidence of the 24-hour circadian cycle in nature in the 18th century. But it wasn’t until the 1970s that scientists began to put real attention toward studying circadian rhythms in humans, and developed the first tool to measure and assess individual chronotypes.

At first, there were two major categories for chronotype: morning and evening. The Morning Evening Questionnaire, developed in the 1970s, gathered information from individuals about sleep and activity to determine whether a person was a “morning” type, an “evening” type, or an “intermediate” type. The MEQ took self-reported information from individuals about their daily sleep-wake habits and analyzed that information with detailed measurements of body temperature changes to determine whether a person had a circadian clock that tilted early or late, or fell somewhere in between. (Remember, body temperature follows a daily rhythm, and evening changes in temperature are a critical part of transitioning to sleep.)

Morning and evening types continue to be used as the two primary chronotypes by many clinicians in assessing patients, and in a lot of the scientific and medical research about how chronotype affects behavior, health, mood, cognition, and sleep.

But many people don’t fit into one of two types. Think about it. If you had to choose, you could probably pick some degree of preference for morning or evening, in terms of your sleep and activity levels. And some people easily and clearly identify as morning people or night people.

But a great many of us don’t. Maybe it’s because our preferences don’t fall clearly to either of these extremes. Maybe it’s because we recognize ups and downs of energy and sleepiness, variable moods, and different types of mental focus, throughout the day and night. And it’s also because there are other factors that contribute to identifying with a chronotype, beyond sleep-wake and activity patterns—including personality and behavior.

The Three Birds: Larks, Hummingbirds, Owls

This general classification system for chronotypes is based on the fundamental distinction between morning-evening chronotypes and also recognizes the great number of people who fall somewhere in between.

  • Larks are the morning types, people who wake early, keep early bedtimes, and experience their peak productivity and alertness in the morning and early afternoon.
  • Owls are up and about at night, evening types who wake up later in the morning, go to bed late in the evenings, and hit their natural focus and productivity peak in the evening hours.
  • Hummingbirds are, well, everybody else. There’s a big middle ground between Larks and Owls, filled with people who don’t fit naturally into either type. As with the MEQ, this three-chronotype categorization theory doesn’t dig deeply into the chronobiological differences for people in this middle-of-the-road category.

As research into chronotype and circadian rhythms progressed in the late 20th century and into the 2000s, we learned a lot more about how individual chronotype influences sleep, but also behavior, personality, and health.

For example, scientific study showed us that morning types (Larks) tend to be more conscientious, agreeable, and positive-minded than other chronotypes. They also tend to be more proactive (willing to take action to achieve advantageous change) and less prone to procrastination.

Research found evening types tended to be more extroverted and more impulsive, and greater seekers of novelty (new and different experiences) than other chronotypes. Being an evening type, studies found, was also linked to greater risk for depression, and more tendency toward risk-taking behaviors, as well as higher consumption of alcohol, nicotine, and caffeine.

More from Michael J. Breus Ph.D.
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