In short
- Your chronotype is where your body clock sits compared with other people: earlier (lark) or later (owl).
- Most people are in between. True extremes are a minority.
- Genes play a part. Large studies have linked hundreds of genetic variants to being a morning person.
- Chronotype changes with age: latest in the late teens and early twenties, then earlier as we get older.
What a chronotype is
Everyone has a body clock, but not everyone's clock is set to the same time. Your chronotype is the natural timing of your clock: when you would fall asleep and wake up if work, school and alarms did not exist.
Larks, or morning types, feel most awake early and get sleepy early. Owls, or evening types, find mornings hard and feel sharpest later. Most people fall somewhere in the middle.
How scientists measure it
Two questionnaires are widely used:
- The Morningness–Eveningness Questionnaire (Horne and Östberg, 1976) asks when you would choose to do things if you were free to plan your day.
- The Munich ChronoType Questionnaire (Roenneberg and colleagues) uses the midpoint of your sleep on free days, when there is no alarm. For example, asleep at 1 am and awake at 9 am gives a midpoint of 5 am.
In the lab, researchers can also measure when melatonin starts to rise in dim light, which is a direct marker of clock timing.
Why you are a lark or an owl
Genes. A study of nearly 700,000 people found 351 genetic regions linked to being a morning person, including several of the core clock genes.
Age. Children tend to be early. Chronotype gets later through the teenage years and is latest at around 20, then drifts earlier through adult life. Researchers have even suggested this turning point as a biological marker of the end of adolescence.
Light. People who get less daylight, especially in the morning, tend to drift later. Spending more time outdoors in daylight tends to shift people earlier.
Social jet lag
When your chronotype and your timetable disagree, you build up a sleep debt during the week and sleep in at the weekend. The gap between your weekday and weekend sleep midpoints is called "social jet lag". Owls usually have more of it, because most work and school days start early.
Find yours in one minute
Our 5-question chronotype check places you on the lark–owl scale. It is a simple guide, not a clinical test. For a quick estimate on your own: on a free day with no alarm, note when you fall asleep and wake up, and work out the midpoint.
| Sleep midpoint on free days | Roughly |
|---|---|
| Before 3 am | Earlier type (lark) |
| 3 am to 5 am | Intermediate |
| After 5 am | Later type (owl) |
These bands are a rough guide only. If you are sleeping a lot more on free days to catch up, the midpoint will come out later than your true type.
Using your chronotype
- Larks: protect your early hours for demanding work, and watch for evening events that push bedtime late.
- Owls: morning daylight and a steady wake time, weekends included, can help pull your clock earlier.
- Everyone: keep caffeine to the earlier part of your own day. For an owl, "2 pm" may be a bit later. For a lark, earlier. See caffeine half-life.
Sources
- Horne JA, Östberg O. A self-assessment questionnaire to determine morningness–eveningness in human circadian rhythms. Int J Chronobiol 1976;4:97–110.
- Roenneberg T, Wirz-Justice A, Merrow M. Life between clocks: daily temporal patterns of human chronotypes. J Biol Rhythms 2003;18:80–90. doi:10.1177/0748730402239679
- Roenneberg T et al. A marker for the end of adolescence. Curr Biol 2004;14:R1038–9. doi:10.1016/j.cub.2004.11.039
- Jones SE et al. Genome-wide association analyses of chronotype in 697,828 individuals provides insights into circadian rhythms. Nat Commun 2019;10:343. doi:10.1038/s41467-018-08259-7
- Wittmann M et al. Social jetlag: misalignment of biological and social time. Chronobiol Int 2006;23:497–509. doi:10.1080/07420520500545979
This article is general education, not medical advice. Listing a study describes the research only. It is not a claim that NOVR has the same effect.