What is a Sleep Chronotype?

Published on February 8th, 2021 and Updated on May 3rd, 2021

You’ve probably heard of early birds and night owls, but what you may not know is that there’s a scientific term for whether you rise with the moon or with the sun: sleep chronotype.

Sleep chronotype is an individual’s natural propensity to sleep at certain times of the day. Understanding your child’s natural sleep chronotype may allow you to create sleep schedules that intrinsically work for her and improve her sleep quality. 

Your child might be a morning person and feel bright and awake at sunrise, becoming your uninvited alarm clock by climbing into your bed in the mornings. Or, she might be a little night owl, begging for one more story, lullaby, or minutes of snuggle time well past bedtime. That’s your child exhibiting her sleep chronotype.

Benefits of knowing your child’s chronotype 

Every new thing learned about your child—whether it’s his love of carrots or his fear of the dark—can help guide decisions that affect his health and happiness. Since sleep and overall sleep quality impact so much of our mind and body, your child’s chronotype can open up many parenting hacks for dealing with newborn sleep patterns and your family’s day-to-day life.

Some benefits of learning your child’s chronotype include:

  • Creating a sleep schedule built for your child – Sometimes, getting your child to go to bed on time (or wake up on time) feels like a daily struggle. Knowing when your child’s circadian clock says “sleep” or “wake” can help you plan a schedule that works for your child’s natural rhythm, so he can feel his best — and you can spend less time putting him to bed and waking him up!
  • Fostering a healthy relationship between sleep and food – Your child’s chronotype can help you plan for his best night’s sleep, and a good night’s sleep may also be the key to healthy eating. Sleep helps the body maintain ideal leptin levels. Leptin is a hormone that sends signals to the brain when the body has enough energy from food or sleep to maintain itself. It does this by managing your child’s appetite. 

When your child’s body has plenty of energy to use, leptin prevents feelings of hunger or cravings. That’s why leptin is produced during sleep and during digestion, the times when your child’s body is storing up energy for the day. When your child doesn’t get enough sleep, his leptin levels dip. As a result, your child’s appetite levels increase to compensate for the loss of energy production, which can lead to overeating and calorie-dense food choices.

  • Making way for mental wellness – You know the difference a good night’s sleep can make for your child’s mood. A 2015 study published in The Journal of Biological and Medical Rhythm Research found that parents who accommodated their child’s chronotype noticed their children had an improved mood and fewer difficulties when it was time to wake up or go to sleep. 

What determines your child’s chronotype? 

Cracking the code to your child’s chronotype can make a huge impact on her health and wellness. Many factors can affect whether your child prefers to stay up late or go to bed early.

  • Age – If you’re used to waking up to big eyes blinking up at you from the side of your bed, you’re not alone. Scientists found that age could play a significant role in chronotype

    • Prepubescent children are more frequently early chronotypes.
    • Adolescents shift toward later bed and wake up times. 
    • After age 20, chronotypes trend earlier and earlier again.
  • Geographic location – Your latitude may affect your child’s inner clock more than her alarm clock! Research shows that the closer people live to the equator—where days and nights are about the same duration year around—the more likely they are to be earlier risers. Individuals who live farther away from the equator—where the duration of nights and days are more drastically affected by the seasons—are more likely to be night owls.

Scientists theorize that geography’s effect on our inner clocks is an evolutionary adaptation, allowing us to maximize sleep and active periods based on the light and dark of wherever we are. So, if you’re planning a move to Ecuador, keep an eye on your child’s sleep schedule—you might notice a change!

  • Genetics – Like her sweet dimples or her big brown eyes, some of your daughter’s traits are due to innate genetics—including chronotype. But there isn’t one single gene that will turn your daughter into a late bird. There’s a whole orchestra’s worth, each contributing to her symphony of z’s. 

Clock Genes: The Genetics of Chronotype

A series of genes work together to help activate our circadian rhythm—the body’s own internal clock that directs us when to wake up and when to fall asleep in a 24-hour period. But some inner clocks are naturally set to wake the body up earlier in the morning while setting a bedtime for early in the evening, or vice versa. 

Scientists call these genes the clock genes. These genes interact with each other on a molecular level to help our bodies run on time.   

Some clock genes include: 

  • CLOCK The CLOCK gene (a little on the nose, yes) is a bit like the orchestra conductor of the clock genes. It activates and leads the rest of the clock genes, allowing them to work together to create the body’s internal clock. 
  • ARNTL2 – If the CLOCK gene is the conductor, the ARNTL2 gene is the assistant conductor. The assistant makes sure all the musicians have their scores, helps the conductor program the concert, and may even conduct a piece or two on the big day.

ARNTL2 helps the CLOCK gene activate and guide the supporting clock genes. It also conducts its own masterpiece by helping maintain the hypothalamus, the brain’s center for sleep regulation. Variants in the ARNTL2 have been linked to circadian rhythms and the timing of sleep cycles. 

  • PER1, PER2, and PER3 – Welcome to the orchestra pit! The PER genes—the Period Circadian Regulators genes—are activated by the CLOCK and ARNTL2 genes. They help by producing the proteins that run the brain’s inner clock, also known as the suprachiasmatic nucleus.

The suprachiasmatic nucleus is your brain’s very own “pacemaker” or, the clock in your brain that regulates when your body’s systems do what. Some studies have found that variations in the PER genes can lead to specific sleep chronotypes.

Chronotype Categorizations 

Internal clock settings have two basic categories, a morning type and evening type. Researchers who expanded these categories provide more insight into the relationship between sleep and health. 

Morning or Evening Types (AKA Night Owls versus Early Birds)

The most basic and comprehensive chronotype sleep categories, morning or evening types, are distinguished by whether a person prefers to stay up late or wake up early.

  • Morning Chronotype or, M-type – This chronotype rises with the sun—sometimes literally! Your little early bird may find himself yawning a little earlier in the night than his bedtime. 
  • Evening Chronotype, or E-type – This chronotype likes to carpe nox, or seize the night! You may notice that your night owl tends to be bright and alert past his bedtime. When it comes to early morning wake-ups, this nocturnal bird may grow up to be a big fan of the snooze button. 

Bears, Wolves, Lions, Dolphins, Oh My! 

Some scientists have expanded chronotype beyond bird analogies. According to sleep expert and clinical psychologist Dr. Michael Breus, Evening Chronotype and Morning Chronotype can be separated into more detail. 

Here’s how Dr. Breus breaks it down:

  • The Bear Chronotype, AKA a little bit of day, a little bit of night – The most commonly occurring of these animal chronotypes, the bear’s sleep cycle operates according to the sun. That means bears tend to wake up and fall asleep early. They’re at their most alert before midday but are susceptible to a “post-lunch” dip in energy between 2 and 4 PM—you might recognize this as your cub’s typical nap time!
  • The Wolf Chronotype, AKA nighttime-lovers – If your child tends to wake up in the late morning and stays active until about 4 PM, you might have a little wolf pup on your hands. A wolf chronotype enjoys a little energy boost at around 6 PM and tend to stay up late, whether they’re enjoying storytime with Mom or howling at the moon. 
  • The Lion Chronotype, AKA early risers – King of the jungles and early wake up times, lion types prefer an early start to the day. Lion types may even wake up before the sun rises! But after a long morning, your Simba or Nala may lose steam at around lunch time. Then, after a meal—and maybe a cat nap—your lion cub will be alert until about 9 or 10 PM. 
  • The Dolphin Chronotype, AKA a little unpredictable – This chronotype is distinguished by its lack of predictability. Dr. Breus notes that while a dolphin chronotype may have a natural genetic predilection towards being an E-type or an M-type, they may also be extremely light sleepers. The struggle to find adequate amounts of sleep can lead to sporadic sleep schedules. But don’t worry, there’s good news. Dolphin types tend to be at their most alert from 10 AM to 2 PM. 

If you are looking for more information regarding your baby’s sleep pattern and schedule, read our article on “When do babies sleep through the night?” for more information! You may also try our sleep DNA test to help you know your child’s sleeping patterns, sleep chronotype, efficiency, duration and more.

For Every Sleep Animal Out There, There’s SneakPeek 

Whether your bird is up early enough to catch the worm or late enough to soar in starlight, a good night’s sleep can make all the difference in your child’s wellness. With SneakPeek Traits, you can see if your little fledgling’s feathers will be those of a night owl or an early bird. You’ll also learn your child’s genetic inclinations for:

  • Ideal sleep duration – The perfect amount of sleep for her body
  • Sleep efficiency – The time your child tends to spend trying to fall asleep versus actually sleeping.
  • Sleep latency – How long it typically takes for your child to fall asleep. 

SneakPeek Traits also comes with tips and tricks for specific genetic traits, so the whole family can learn how to get their best night’s sleep every night. Start today with SneakPeek Traits!


Healthline. Chronotypes, Sleep, and Productivity. https://www.healthline.com/health/chronotype

ScienceDirect. Relationship between Circadian Rhythms, Feeding, and Obesity. https://www.sciencedirect.com/topics/psychology/chronotype

US National Library of Medicine. Chronotypes in the US – Influence of age and sex. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5479630/

Chronobiology International. The influences of chronotype in the daily lives of young children. https://www.tandfonline.com/doi/abs/10.3109/07420528.2016.1138120?journalCode=icbi20

Oxford Academic. Chronotype: Implications for Epidemiologic Studies on Chrono-Nutrition and Cardiometabolic Health. https://academic.oup.com/advances/article/10/1/30/5209973

PubMed. Latitudinal cline of chronotype. https://pubmed.ncbi.nlm.nih.gov/28710358/

PubMed. Genetic Basis of Chronotype in Humans: Insights From Three Landmark GWAS. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6084759/

US National Library of Medicine. Short Sleep Duration Is Associated with Reduced Leptin, Elevated Ghrelin, and Increased Body Mass Index. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC535701/

Oxford Academic. Leptin Levels Are Dependent on Sleep Duration: Relationships with Sympathovagal Balance, Carbohydrate Regulation, Cortisol, and Thyrotropin. https://academic.oup.com/jcem/article/89/11/5762/2844744

University of Fribourg. Clock Genes. https://www.unifr.ch/biochem/assets/files/albrecht/publications/AlbrechtRipperger.pdf

Gene Cards. CLOCK Gene. https://www.genecards.org/cgi-bin/carddisp.pl?gene=CLOCK

Gene Cards. ARNTL2 Gene. https://www.genecards.org/cgi-bin/carddisp.pl?gene=ARNTL2

Gene Cards. PER2 Gene. https://www.genecards.org/cgi-bin/carddisp.pl?gene=PER2

Business Insider. I had a ‘sleep doctor’ tell me how to structure my entire day, and I’ve never felt more energized. https://www.businessinsider.com/i-structured-my-day-according-to-my-chronotype-2016-9

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SneakPeek aims to provide the most accurate and up-to-date information to help our readers make informed decisions regarding their health before, during, and after pregnancy. This article was written based upon trusted scientific research studies and/or articles. Credible information sources for this article are cited and hyperlinked.

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