How to Calculate Chronotype
What is Chronotype?
Chronotype describes an individual's natural preference for morning or evening activity, driven by genetic factors (particularly the PER3 gene). About 15% of people are extreme "larks" (morning types), 15% extreme "owls" (evening types), with 70% in between.
Step-by-Step Guide
- 1Sleep midpoint = time halfway between sleep onset and wake time
- 2Corrected midpoint (free days) is most accurate
- 3Owls: midpoint after 5am · Larks: midpoint before 3am
- 4Chronotype shifts with age: teens skew owl; adults become larks
Worked Examples
Input
Sleep 11pm · Wake 7am
Result
Sleep midpoint = 3am → Intermediate chronotype
Owl = midpoint >4am; Lark = midpoint <3am
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