Two · Inside you

Your body clock.

Nineteen windows in your day, computed from the light you actually get where you are — when to sit in the light, when the last coffee is, when to sleep, and when to take care.

Published chronobiologyTo the secondYour latitudeSources named

What we measure

Nineteen windows.

Each window is a number with the model it came from named. Four groups: the clock itself, sleep and alertness, sun and the seasons, travel and work — and one contested window, shown with both sides on the table.

Your solar daysunrise, sunset, day length, and how high the sun gets
Your clock’s phasetemperature low, melatonin onset, ideal bedtime, wake
Shift with lighthow far a bright-light session moves your clock, and when
Melanopic daylighthow much melatonin-active light today carries
Smart lightinga dawn-to-dark plan, and the warm-to-cool lamp ramp
Caffeine cutoffthe last real coffee, and how long it lingers
Perfect napthe post-lunch dip, and when to stop
Peak performancemorning focus, late-afternoon strength, the dip between
Danger hoursthe pre-dawn trough and the morning cardiac surge
Melatonin timingwhen, which way, and doses that work
UV & sunburntoday’s index, and minutes to one sunburn dose
Vitamin-D windowwhen the Sun is high enough, if at all today
Winter-blues windowthe morning light slot, graded to your latitude
Season trackerday length, and how fast it is changing
True noonwhy clock-noon is not sun-noon where you live
Golden hourevery twilight step, and the photo bands
Beat jet lagdays to adapt, which way, and the light plan
Shift-work strainforced hours against natural wake, scored
Moonlight & sleepcontested — both sides shown

Live today

Lived by, daily.

Each one reads the light your place actually gets, so the windows move when you do.

The apps →

Circadian mugScan it with your first coffee and see your whole day before it starts.
PomodoroFocus blocks set by your body clock, or plain 25 and 5, with one switch.
Shift plannerYour shifts in, your night planned: the worst hours, the nap, light, sleep.
Jet lagYour trip in, your days planned: the light each day, the landing day.
FlowA cycle tracker that tells you how sure it is.
Sun doseHow much sun your skin gets today, and when it is enough.
DriverLow sun in your eyes, headlights, and the energy you drive on.
Make-upThe colour of each light on your face, lamp to daylight, in kelvin.
WeatherTemperature, rain and wind for the next 48 hours, right where you are.
WakeAn alarm set to an event, not to a number.
ChoresThe forecast, rewritten as do it now.
PlantingDay length, light ceiling and warmth for a plant, where it grows.

Set to order

Reports and plans.

The body clock is printed to the case in front of it, not to a rack of fixed titles. Name the route and we set a jet-lag plan for it; name the ward or the crew and we set the rotation; name a latitude and we set the year in light. Each is computed for those exact people in that exact place, then typeset and delivered print-ready.

A jet-lag plan for one route and one departure
A shift rotation for a ward, a crew or a plant
A year in light for one latitude

A Year of Daylight: the length of the day through a year at one latitude, with the solstices, the equinoxes and the civil twilight band marked — **A year in light** — the third of the three, as it prints. The length of every day at one latitude, the twilight either side of it, and the solstices and equinoxes marked where they fall. The longest day, the shortest day and the swing between them are given as measured figures at the foot. Name a different latitude and the whole curve is recomputed for it.

Ask for a plan

Build with it

Nineteen windows, in your own code.

The full set of body-clock windows against the real sun at your caller’s latitude: sleep and wake, caffeine, light-shift, melatonin timing, alertness peaks, UV dose and vitamin D, jet lag and shift strain. Each returned as a number, with the published model it came from named alongside it.

Against real light — the sun at the caller’s own horizon, not a nominal day
To the second — instants, not buckets
Any place, any date — the same method everywhere
Named models — every window cites the chronobiology it implements
Plain JSON — small, flat, boring on purpose
No advice — you get the window, not our opinion of what to do in it
Nothing retained — health-adjacent input is answered and discarded
Stable shapes — fields are added, never renamed under you

Want it wired into a rota, a scheduler or an app you already run, or built into software of your own? Ask for that instead. And if you have looked at this and concluded it could not be done, bring it here and let us give it a second thought.

Tell us what you are building API, integrations and bespoke software →

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