Larks and owls: your chronotype
You will be able to: Place yourself on the morning-evening range and turn it into a timing plan, without treating it as destiny.
In Module 1 you took a quick body-clock check. Now that you know about the two switches, you can see what it measures: roughly when your body clock runs, compared with other people's. Scientists call this your chronotype.
What shapes your chronotype
- Genes. A genetic study of almost 700,000 people found 351 places in our DNA linked with being a morning person. Their combined effect on timing is modest: the 5% of people carrying the most "morning" variants slept, on average, only about 25 minutes earlier than the 5% carrying the fewest.
- Age. A study of more than 50,000 people in the US found that, on average, people get later through the teenage years, reach their latest at about 19, and then drift earlier again as they get older.
- Light. In a summer camping study with natural light only, people's body clocks ran earlier than in their normal lives, and the later types moved the most. Modern life, with less daylight and more evening light, was linked with a later clock. This is the part you can change.
Most people sit somewhere in the middle. The labels "lark" and "owl" describe the two ends of a smooth range, not two separate kinds of people.
Take it again, then make a plan
Answer for how you naturally are. Where a question asks about free days, think of days when you do not have to fit anyone else's timetable. If you took the check in Module 1, your earlier result shows alongside, so you can see whether a week of noticing your sleep has changed your answers.
Using your type without being ruled by it
Your chronotype is useful for planning when you do things: when to schedule focused work, when to exercise, when an early meeting will cost you most. It is less useful as a reason to drop your anchor time. A steady wake-up time and morning daylight are worth having for every type, and they matter most for owls, because the gap between work days and free days tends to be largest for late types.
If you are a strong owl with an early job, the honest picture is that you are working against your clock. Morning light and dim evenings may move it somewhat earlier, but early mornings may still never feel natural. That is normal, not a failure.
Quick check (3 questions)
Sources
- Depner et al. (2019), Ad libitum weekend recovery sleep fails to prevent metabolic dysregulation during a repeating pattern of insufficient sleep and weekend recovery sleep, Current Biology 29(6): 957-967, PubMed 30827911 (a later-running clock after weekend catch-up sleep)
- Fischer et al. (2017), Chronotypes in the US: influence of age and sex, PLoS One 12(6): e0178782, PubMed 28636610
- Jones et al. (2019), Genome-wide association analyses of chronotype in 697,828 individuals provides insights into circadian rhythms, Nature Communications 10(1): 343, PubMed 30696823
- Wright et al. (2013), Entrainment of the human circadian clock to the natural light-dark cycle, Current Biology 23(16): 1554-8, PubMed 23910656
- Wittmann et al. (2006), Social jetlag: misalignment of biological and social time, Chronobiology International 23(1-2): 497-509, PubMed 16687322 (most people between the extremes; late types and work-day sleep debt)
- Khalsa et al. (2003), Journal of Physiology 549(3): 945-52, PubMed 12717008
- AASM Sleep Education, Delayed sleep-wake phase and Advanced sleep-wake phase (circadian rhythm sleep-wake disorders, such as delayed and advanced sleep-wake phase)
- NHS, Where to get urgent help for mental health (111, 999 and Samaritans)
The quiz questions and scoring are our own and have not been validated.
Next: try this tonight, morning light and your caffeine cut-off