Updated on September 14, 2018

It’s no secret that some people seem to operate according to completely different internal clocks. It’s common to hear someone self-identify as a “morning” or “evening” person or to describe a daily routine that is totally at odds with yours. This isn’t just a matter of chance; instead, it’s a reflection of chronotypes.

What Are Chronotypes?

Chronotypes help determine our normal schedule of daily actions, including sleep. They affect the times of day when we have the most energy and when we feel sleepy. They are not chosen but are instead genetic and affected by a specific gene called PER3. This gene and our chronotypes directly influence our Circadian rhythm (our sleep-wake cycle), which plays a huge role in sleep.

What Chronotypes Exist?

Though not entirely clear-cut, there are generally four categories of human chronotypes that are named using animal descriptors based on research done by Dr. Michael Breus, Ph.D., a clinical psychologist and sleep expert, and explained in his book, The Power of When.

  • Lions (also known as early birds): people with this chronotype have the most energy in the morning and are best served by getting up and getting started with their most important tasks in the morning. Since they start losing steam later in the day, lions usually have an earlier bedtime.
  • Wolves (also known as night owls): people who are wolves are the opposite of lions. They stay up later, wake up later, and are more effective in the middle to later parts of the day.
  • Bears: bears have energy that tends to conform with daylight. The middle of the day is their most productive time, and they usually don’t have issues getting to sleep at night.
  • Dolphins: people with this chronotype have issues in establishing regular sleep routines and may be light sleepers who are easily disturbed. Insomnia is more common in dolphins for this reason. This can make energy levels during the day fluctuate based on recent sleep, but most dolphins work best during the middle of the day.

It is estimated that bears make up about 50% of the population, lions and wolves make up 15-20% each, and dolphins are about 10%.


How Can Chronotypes Cause Sleep Problems?

Sleep problems may be related to a person’s chronotype for two main reasons. First, a person’s chronotype may not be in alignment with their personal and social calendar and responsibilities. For example, someone who has a wolf chronotype may nevertheless have a job that requires them to wake up early and taken on serious work responsibilities early in the day. The same could be the case for a lion who does shift work that requires working nights.

In both cases, the problem isn’t with the chronotype itself but rather with the misalignment between the person’s chronotype and his or her work requirements. And it’s not always work that causes these issues. Social events may require someone to disrupt their natural sleep tendencies, or a couple who shares a bed may have varying chronotypes. Environmental interruptions (such as increased light or noise) may make it harder to sleep in accordance with a chronotype, especially for night owls.

The second way that chronotypes can cause sleep issues relates specifically to dolphins. People with this chronotype are lighter sleepers and thus have a higher propensity for sleep disruptions. This makes consistent sleep difficult and makes them susceptible to insomnia that can lead to daytime sleepiness regardless of their social or work schedule.

Can You Change Your Chronotype?

Chronotypes may change with age, but a person cannot deliberately switch their chronotype. During adolescence and teenage years, it is normal for someone’s chronotype to lean toward being a wolf. Teenagers usually trend toward staying up late and waking up late. Later in life, people tend toward a lion chronotype in which they go to bed earlier and have more energy early in the day. These changes happen naturally and cannot be forced or induced.

How Can You Adjust to Your Chronotype?

Since you can’t intentionally change your chronotype, the best approach is to work to adapt your life, as much as possible, to your natural sleep rhythm. If possible, choose a job or negotiate a work schedule that aligns with your most productive times. At work, try to build in time to accomplish your most important tasks (whether it be meetings, writing, strategizing, etc.) when you will have the most energy and focus. The same idea applies with regard to your social schedule. Whenever you can, try to organize events or plan your calendar in ways that won’t cause dramatic disruptions to your preferred sleep-wake cycle.

Regardless of your chronotype, it also makes sense to focus on good sleep hygiene. This means trying to standardize, as much as possible, your sleep routines and to optimize your bedroom as an environment for sleeping. Having a base level of sleep hygiene can help you make the most of the time you have available for sleeping and can help reduce the impact of disruptions that may come about when your daily responsibilities are at odds with your chronotype.

Lastly, remember that your chronotype isn’t all-determining. Just because you have a night owl chronotype doesn’t mean that you are going to be useless and ineffective in the morning. Do your best to follow your chronotype, but don’t feel like it is all-encompassing of how you feel or function.


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