Chronotypes & Sleep: Definition, Types, & Effect on Circadian Rhythms

Sleep in sync with nature.
Chronotypes & Sleep: Definition, Types, & Effect on Circadian Rhythms
Tom Greenspan
December 21, 2022

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Wondering how your friend can nail the 5 am morning routine while you are hardly awake by noon? 

Or have you ever noticed how some people function perfectly fine on just a few hours of sleep while others need a full eight hours to feel rested? Well, the answer lies in our chronotypes. Don’t worry; the concept isn’t as difficult as it sounds!

The word chronotype simply refers to our individual biological clocks that determine our natural sleep and wake patterns. As such, understanding your chronotype and circadian rhythm is not only fascinating, but it can also have a significant impact on your health and well-being.

In fact, those who follow a consistent sleep schedule according to their sleep-wake cycle hardly face trouble falling asleep and are more alert during the day. They also have a lower risk of developing certain health conditions.

So, whether you're a morning person or a night owl, read on to discover how to make the most of your natural sleep-wake patterns.

What Are Chronotypes?

Chronotypes are individual variations in our natural sleep and wake patterns. It's the reason why some people feel most alert and productive in the morning while others hit their stride in the afternoon or evening. 

Our chronotype is determined by our biological clock, which regulates our circadian rhythm or our internal 24-hour clock. There are different types of chronotypes, with early birds being morning people and night owls preferring to stay up late. Additionally, some people fall in between and are considered "neutral" or "intermediate" chronotypes. 

It’s also important to understand that your chronotype explains more than just the right time for you to sleep and wake up. It is your body’s internal clock for various primal activities, like eating, socializing, having sex, etc. 

How Chronotypes Work?

Chronotypes are determined by your genes, specifically your PER3 gene, which affects your circadian rhythms and internal body clock. The length of your PER3 gene determines how much sleep you require, in addition to your sleep and wake times.

Early birds tend to have longer PER3 genes, while night owls tend to have shorter ones. While early risers and night owls are well-known types of chronotypes, there are other types, as listed below:

1. Lion Chronotype

Also known as the early bird or the “morning lark,” individuals falling in this category wake up early and feel most alert and productive early morning. They typically feel sleepy earlier in the evening and hence, fall asleep earlier. Around 15-20% of the population are lions.

2. Wolf Chronotype

Wolves or night owls prefer to stay up late and feel most alert and productive in the evening. They may struggle to wake up early in the morning and may feel most alert later in the day. Similar to lions, wolves also make up 15-20% of the population.

3. Bear Chronotype

Representing 50-55% of the population, the sleep schedule of a bear tends to follow the sun. They feel the most energetic during the day and easily fall asleep at night. It is safe to say that these individuals are a mix of early birds and night owls, as they may feel alert and productive during both morning and evening hours. However, they are not immune to the mid-afternoon slump.

4. Dolphin Chronotype

These individuals do not have a consistent sleep pattern and may have difficulty sticking to a regular sleep schedule. They may struggle with insomnia or feel sleepy at unusual times. Most of them are light sleepers who make up 10% of the population.

Chronotypes And Sleep Disorders

Broadly, individuals are categorized into four chronotypes, as mentioned above. However, there are variations to these poles, such as those that rise early but only become active mid-morning. 

Similarly, night owls tend to sleep more on weekends to make up for sleep debt accumulated during the week. So, to identify which category you fall in, an eveningness-morningness questionnaire or a chronotype quiz can be helpful.

Circadian Rhythm Sleep Disorder

In cases where the aforementioned tendencies significantly affect a person's daily life, it can be considered a circadian rhythm sleep disorder. The two common types of this disorder include Advanced Sleep Phase Syndrome (ASPS) and Delayed Sleep Phase Syndrome (DSPS). 

ASPS involves individuals with an extremely early circadian rhythm, leading them to tire early and wake up early in the morning. DSPS, on the other hand, affects those on the opposite end of the spectrum, causing them to tire and wake up much later than others.

The issue in either of these situations is not disturbed sleep, as sleep quality is generally unaffected. Rather, the problem is the impact on their daily functioning and overall well-being. They often do not get enough sleep to attend social or work events or may suffer from insomnia because they are unable to sleep when others are sleeping.

Social Jet Lag

If a person was to live alone with no interactions with others, their chronotype would not pose any problems. However, conflicts arise when they have to live and work with others. 

Even individuals without a circadian rhythm sleep disorder, such as ASPS or DSPS, may face difficulty adhering to their employer's schedule. Or, they may have to adjust according to social events, regardless of whether it corresponds to their optimal energy levels. This disparity is known as social jet lag, which is a persistent condition, unlike real jet lag.

Can You Change Your Chronotype?

Unfortunately, you cannot switch from being an early chronotype to a night owl or vice versa. Our biological predisposition to a particular chronotype is difficult to change, although it may naturally shift as we age. While there are techniques like exposure to bright light or taking melatonin supplements to adjust our circadian rhythms, they are not long-term solutions and should be discussed with a doctor. 

However, chronotherapy has been used effectively to treat delayed sleep phase type circadian rhythm sleep disorder. The process gradually adjusts the sleep schedule until the desired sleep and wake times are achieved.

Adolescents experience a natural shift in their circadian rhythms towards later in the evening, which can be challenging when school start times are early. To address this issue, sleep experts recommend later school start times to improve the well-being of teens.

Why Is Knowing Your Chronotype Important?

Numerous studies have demonstrated the importance of chronotype in relation to personality, health, and quality of life.

Morningness is associated with traits, such as agreeableness and conscientiousness, while eveningness is linked to creative thinking, openness to experience, and neuroticism. Similarly, morning people tend to excel academically, while evening types may have an advantage in creative professions. 

Eveningness is further associated with unhealthy habits, such as physical inactivity, poor sleep quality, and irregular sleep schedules, which increase the risk of various health issues. As such, night owls are more likely to suffer from obesity, metabolic syndrome, type 2 diabetes, sleep apnea, and mental disorders. 

Additionally, eveningness is linked to negative habits like anger, anxiety, impulsivity, and depression, as well as increased risk-taking behaviors and substance abuse. 

While genetics may play a role in determining an individual's chronotype, irregular sleep schedules caused by forced adaptation to early wake times may also contribute to these outcomes. Adherence to a routine that mismatches one's chronotype can negatively affect worker health, highlighting the importance of matching shifts to an individual's chronotype. However, this may not always be feasible.

Various interventions, such as melatonin supplements, light therapy, and good sleep hygiene practices, may help shift an individual's circadian rhythm. Accordingly, they may be able to reduce the effects of social jetlag and insomnia.

How To Adjust Your Sleep Schedule According To Your Chronotype?

If you try to work against your body's natural sleep-wake cycle, you may struggle with falling asleep or staying awake, and experience disrupted sleep. Instead, it's better to embrace your chronotype by going to bed when you feel tired. Accordingly, schedule important tasks during your most productive times, and plan enjoyable activities when you feel most alert.

It’s also important to stop judging yourself based on your chronotype because it's simply a natural aspect of your body's sleep-wake cycle and doesn't reflect your worth as a person. Each chronotype has its own unique strengths and weaknesses, and given below are some ways you can hack your productivity by adhering to your chronotype!

1. Lion Chronotype

Lion chronotypes are the “society’s favorite” morning people, so their energy and productivity peak early in the day. Hence, they must prioritize important, “bigger” tasks in the morning and avoid meetings in the late afternoon. Establishing a bedtime routine can further help maintain energy levels throughout the day.

Consider waking up by 6 am and focusing on “deep work” from 8 am to 12 pm. Thereafter, indulge in lighter tasks till 4 pm. Then slowly unwind and relax for the day. By 9-10 pm, you should be ready for bed. 

2. Wolf Chronotype

They are slow to start and hit their peak later in the day, so it's best to avoid important meetings in the morning. Taking short breaks and finishing demanding tasks after dinner can help them stay productive.

This evening chronotype usually gets going after the sun sets, and may find it easy to stay awake late into the night. So, if you are among the wolf chronotypes, try waking up by 7:30-9 am, and focus on lighter tasks first. Then proceed to complete bigger tasks or creative work till 2 pm. 

Again, focus on lighter, less intensive tasks till early evening, and get back to creative work till 9 pm. Thereafter, unwind and prepare for bed, and sleep at 12 am. 

3. Bear Chronotype

For "Bear" chronotypes, it's best to start and end the day slowly because their productivity peaks in the morning and declines steeply after lunch. Mid-morning is the best time for important meetings, while afternoon tasks should be less intense.

Owing to their continuous flow of mellow energy, bears should ideally wake up by 7-8 am and focus on deep work from 10 am to 2 pm. Then it’s best to shift to lighter tasks till 4 pm. Slowly, they should relax and unwind, and finally, call it a day by 11 pm. 

4. Dolphin Chronotype

"Dolphins" have a constantly active brain, so starting the day with simple tasks can help them prepare for more intense work. They should take advantage of creative inspiration whenever it strikes and avoid distractions before bedtime, as they can have trouble sleeping.

So, if you identify with the dolphin chronotype, your ideal time to wake up is between 6:30 and 7:30 am. Engage with easy work till 10 am and then proceed to demanding tasks till 12 pm. Again, shift to lighter work from 12 pm to 4 pm, and then relax for the day. Go to bed latest by 12 am.

Circadian Rhythm (Sleep-Wake Cycle) Vs. Chronotype

It is essential to differentiate between chronotypes and circadian rhythms when discussing sleep patterns. Although they are similar, each plays a distinct role in sleep and can be used to comprehend your habits and enhance productivity.

Circadian rhythms control your sleepiness and alertness levels and are governed by the brain's hypothalamus, also known as “sleep-wake cycles.” These internal clocks regulate when you feel like sleeping and waking up. The circadian rhythms in most adults are lowest between 2 am and 4 am, although this may vary depending on whether you're a night owl or an early bird.

Chronotypes, on the other hand, serve as a tool for understanding how circadian rhythms impact daily life. They are generally viewed as a means of increasing productivity and can assist in comprehending how sleep schedules impact your alertness and the best time to complete specific tasks.

Studies on chronotypes began in the 1970s and have since been expanded and standardized to the four animal chronotypes used today. These animals help to classify and generalize the circadian rhythms found in nature.

Although chronotypes are not an exact science, they provide an interesting way to learn more about yourself. People generally fall into one of the four categories, but it is common to exhibit subtle traits of more than one.


Although circadian rhythms and chronotypes are relatively consistent, daily energy levels have too many variables to precisely define when tasks should be completed. This guide will hopefully aid in understanding your work habits and becoming more efficient in the process.

Regardless of your chronotype, it is important to feel comfortable in bed, get a good night's sleep, and feel refreshed the next morning!