Chronotype is the personal tendency toward earlier or later sleep and peak alertness, sitting on a spectrum from clearly morning-shifted through neutral to clearly evening-shifted. It is partly genetic, partly age-driven, and partly shaped by light exposure and schedule habits over time.
Why it matters for stack timing
Two users with identical stacks can produce different logs simply because their internal clocks run on different schedules. Matching dose windows to chronotype usually beats forcing a generic morning or evening template that ignores the user in front of you.
Common patterns
- Morning-shifted. Cortisol rises early, peak focus lands before noon, and sleep pressure builds by mid-evening.
- Neutral. Wake and sleep cluster near the social clock, with a broad mid-day work window.
- Evening-shifted. Alertness builds late, sleep onset drifts past midnight, and the morning starts slow.
Field-level operating notes
For an evening-shifted user, an 8 am stimulant may land during a low-arousal phase, while the same dose at 10 am may be easier to read. For a morning-shifted user, an evening calming entry may need an earlier window because the wind-down begins earlier. Sleep-active compounds are easier to compare when placed against the user's real sleep block tracked through the bedtime dose window rather than the local clock.
Estimating your chronotype
A short morningness-eveningness questionnaire is a starting point, but two weeks of logged wake time, sleep onset, and self-rated peak focus is usually more informative than a single survey result.
Cross-site references
Uncertainty
- Evidence is limited on how much chronotype can shift with sustained light and behavior changes.
- Evidence is limited on chronotype-specific dose response for most supplements.
How this appears in Unfair
Unfair uses your reported wake time, sleep block, and peak-focus window to shape default dose windows so the schedule reflects your chronotype rather than a one-size template.
Clinical safety note
Extreme evening-shift with daytime impairment, especially in younger users, may reflect delayed sleep-wake phase disorder and is worth raising with a clinician.