Instrument 06 / one day
Circadian Clock
The page begins with an Amsterdam sunlight demonstration and your device's local civic time. Adjust a preferred sleep window, or request location only if you want local solar calculations.
Amsterdam demonstration remains active until you choose and permit location access.
Coordinates remain in this browser session, where they are used only for calculations; they are not stored or sent anywhere.
What this does not measure
This page compares civic time, calculated sunlight, and a routine you choose. It does not measure hormones, melatonin, sleep quality, alertness, chronotype, or your biological clock. Solar times are browser calculations rather than an official almanac.
Why this clock exists
A systematic review indexed by the National Library of Medicine describes light as an environmental timing cue and finds that both amount and timing of exposure matter for sleep outcomes. This clock cannot observe light exposure or sleep. It places three public and chosen schedules beside one another instead: civil hours, calculated daylight, and a preferred routine, each following a different authority.
Systematic review of light timing and sleep