Jet-Lag Optimization Scheduler

How do I plan a schedule to beat jet lag for my flight?

Pick your home city and destination, enter your usual bedtime and wake time, and AnyTool Jet-Lag Optimization Scheduler works out whether you need a circadian phase advance (eastward — sleep and wake earlier) or phase delay (westward — sleep and wake later), taking the shorter way round when the gap exceeds 12 zones. It estimates the days to fully adjust at about one time zone per day and builds a day-by-day plan with your sleep window, when to seek bright light, when to avoid light and optional evening melatonin — each sliding about an hour a day toward destination time. Everything is calculated in your browser, so nothing is uploaded.

Eastward = phase advance (earlier); westward = phase delay (later)
Light is the strongest cue: seek it on the right side of your body-clock minimum
Adjusts at roughly one time zone per day; the plan shifts ~1 h per day
Optional evening melatonin on eastward trips; doctor-gated and approximate
100% in your browser — DST-aware city zones, no upload, works offline

What is

Jet lag (desynchronosis)

Jet lag is the temporary mismatch between your internal circadian clock and local time after crossing time zones, causing poor sleep, daytime fatigue and reduced alertness. Eastward travel requires a phase advance (shifting sleep earlier) and is generally harder than westward travel, which requires a phase delay (shifting sleep later). Recovery takes roughly one day per time zone crossed, and is sped up by timing bright light, sleep and sometimes melatonin around the core-body-temperature minimum, which falls about two to three hours before habitual wake.

Calculators

Related terms

Circadian rhythmPhase advancePhase delayCBTmin (core-body-temperature minimum)Melatonin

Frequently Asked Questions

Travelling east puts local time ahead of home, so your body clock must advance — you go to sleep and wake earlier — and most people find that harder than delaying. Travelling west puts local time behind, so the clock delays and you stay up later, which is easier because our natural day runs slightly longer than 24 hours. AnyTool detects the direction from your two cities, labels it as a phase advance or delay, and builds the matching light and sleep schedule.

Flying east is usually harder because it needs a phase advance — shifting your sleep earlier — which the body resists more than the phase delay that westward travel needs.

A widely used rule of thumb is that the body re-synchronises at roughly one time zone per day, so the number of zones you cross is a good first estimate of the days to fully adjust. AnyTool caps very long trips, takes the shorter way round when the gap exceeds twelve zones, and shifts your sleep and light windows about an hour a day, which — combined with correctly timed bright light — can speed adaptation beyond the one-zone-a-day baseline.

About one time zone per day, so a six-zone trip takes roughly six days to fully adjust — faster with well-timed light.

Light is the strongest signal for the body clock, and its effect flips around your core-body-temperature minimum, about two to three hours before you normally wake. Light after that minimum advances the clock (good for eastward trips), while light before it delays the clock (good for westward trips). So to advance you seek morning daylight and dim screens at night; to delay you seek evening light and wear shades or stay dim in the early morning. AnyTool places the seek and avoid windows on the correct side of that minimum and slides them each day.

To shift earlier (east) seek morning light and avoid late-evening light; to shift later (west) seek evening light and avoid early-morning light.

Melatonin nudges the clock opposite to light: an early-evening dose can help pull the clock earlier on eastward trips, which is why AnyTool only suggests it on advance plans and frames it as optional. Timing, dose and suitability vary, so talk to a doctor before using it — especially if you are pregnant, take medication or have a health condition. The scheduler resolves your city offsets with the browser’s own time-zone data and does all the arithmetic locally, so your trip details never leave your device and the page works offline.

Low-dose evening melatonin can help eastward trips, but ask a doctor first — and nothing is uploaded; the plan is built entirely in your browser.

Build a personalised, day-by-day plan to beat jet lag: detect whether your trip needs a circadian phase advance (east) or delay (west), estimate the days to adjust at ~1 zone/day, and time your sleep, bright-light, light-avoidance and optional melatonin windows — all in your browser.

Features

Phase advance vs delay from your two cities, with the shorter way round past 12 zones
Day-by-day sleep, light-seek, light-avoid and optional melatonin windows
Light timing anchored to the core-body-temperature minimum (~2–3 h before wake)
DST-aware city offsets via the browser; pre-trip prep days; copyable plan
Honest not-medical-advice limits — 100% client-side, nothing uploaded

PriceFree

CategoryCalculator

PlatformAll (browser-based)

PrivacyTrip and sleep details never leave your device

Input: Home and destination city, Usual bedtime and wake time (HH:MM), Days to prep before the flight

Output: Direction (advance/delay), Days to adjust, Day-by-day sleep / light / melatonin schedule

Detailed Explanation

Methodology

How the Jet-Lag Optimization Scheduler Works

AnyTool Jet-Lag Optimization Scheduler resolves the UTC offset of your home and destination cities live from the browser’s own IANA time-zone data, so daylight saving is handled automatically, then subtracts them to get the signed time difference. A pure, clock-free engine reduces that difference to the shorter way round (within ±12 hours), which decides the direction: a positive result means destination time is ahead, so you need a circadian phase advance (sleep earlier, eastward); a negative result means a phase delay (sleep later, westward). It estimates the days to fully adjust at about one time zone per day, then generates a day-by-day schedule that slides your sleep, light and melatonin windows roughly one hour per day toward destination time. All arithmetic runs in your browser with nothing uploaded.

City offsets resolved live and DST-aware via the browser, then differenced
Shorter way round (±12 h) sets phase advance (east) vs delay (west)
Days to adjust ≈ one time zone per day, capped for very long trips
Sleep and light windows shift ~1 h per day toward destination time
Clock-free engine; all math is client-side JavaScript, nothing uploaded

How It Works

Light Timing Around the Body-Clock Minimum

Light is the strongest zeitgeber, and its direction of effect flips around the core-body-temperature minimum (CBTmin), which falls roughly two to three hours before habitual wake. Bright light after CBTmin advances the clock, while light before CBTmin delays it. The scheduler uses this to place windows correctly: on an advance (eastward) plan it tells you to seek morning daylight and avoid bright light late in the evening; on a delay (westward) plan it tells you to seek evening light and avoid bright light in the early morning. Each day’s seek and avoid windows are anchored to the shifting wake time so they stay on the right side of the minimum as you adapt.

CBTmin ≈ 2–3 hours before habitual wake time
Light after CBTmin advances the clock; light before it delays the clock
Advance (east): seek morning light, avoid late-evening light
Delay (west): seek evening light, avoid early-morning light
Outdoor daylight is far brighter than indoor lighting

Limitations

General Guidance, Not Medical Advice

The schedule turns well-established circadian principles into concrete times, but it is educational guidance rather than medical advice, and the windows are approximate. It assumes a typical CBTmin about two to three hours before your usual wake time and a steady one-hour-per-day shift, whereas real adaptation varies with age, chronotype, sleep debt, individual light sensitivity and how well you can control your light environment. Melatonin is only suggested on eastward (advance) plans and is explicitly optional and doctor-gated, because dose, timing and suitability differ between people. The tool advises consulting a doctor before using melatonin and before following any plan if you are pregnant, have a sleep, mood, eye or heart condition, take medication, or must drive or operate machinery on little sleep.

Educational guidance, not medical advice; times are approximate
Assumes CBTmin ~2–3 h before wake and a ~1 h/day shift
Individual response varies with age, chronotype and light control
Melatonin suggested only on eastward plans, optional and doctor-gated
Consult a doctor for melatonin, pregnancy or health conditions

Privacy & Security

Privacy and Offline Use

Because every step — resolving city offsets, deciding direction and building the day-by-day plan — runs in the browser, your cities, sleep times and trip details are never sent to a server, there is no account or tracking, and the page works offline after first load. The plan can be copied as plain text to paste into your notes or calendar.

Jet-lag planning: in-browser (AnyTool) vs typical online jet-lag calculators
Capability	AnyTool	Typical online calculators
Processing	Runs in your browser	Often server-side
Direction logic	Phase advance vs delay, shorter way round	Sometimes just "east/west"
Light timing	Seek + avoid windows around CBTmin	Often vague or missing
Schedule	Day-by-day sleep / light / melatonin	Often a single tip list
Time zones	DST-aware city offsets via browser	Static offset tables
Melatonin	Optional, eastward only, doctor-gated	Often blanket advice
Works offline	Yes (PWA)	No
Cost / signup	Free, no signup	Often ad-heavy or gated

AnyTool builds the whole schedule locally and uploads nothing. It is general guidance, not medical advice.

Cite This Page

Title: Jet-Lag Optimization Scheduler (phase advance vs delay, day-by-day light, sleep and melatonin timing around CBTmin, DST-aware city zones, no server)
Author: AnyTool
Published: January 1, 2026
Modified: February 8, 2026
Section: Calculators
URL: https://www.anytool.tech/jet-lag-optimizer

Formatted Citation

AnyTool. "Jet-Lag Optimization Scheduler (phase advance vs delay, day-by-day light, sleep and melatonin timing around CBTmin, DST-aware city zones, no server)." AnyTool, January 1, 2026. https://www.anytool.tech/jet-lag-optimizer

A privacy-first, 100% client-side jet-lag planner that builds a personalised, day-by-day schedule to re-synchronise the body clock after crossing time zones. It resolves the home and destination city offsets live and DST-aware from the browser’s own IANA time-zone data, differences them, and reduces the gap to the shorter way round within ±12 hours to decide whether the trip needs a circadian phase advance (destination ahead, eastward — sleep and wake earlier, generally harder) or a phase delay (destination behind, westward — sleep and wake later). It estimates the days to fully adjust at roughly one time zone per day, capped for very long trips, then produces a plan that slides the sleep window, a bright-light seek window, a light-avoidance window and an optional early-evening melatonin time about one hour per day toward destination time, optionally beginning a few prep days before departure. The light windows are anchored to the core-body-temperature minimum (CBTmin), about two to three hours before habitual wake, because bright light after that minimum advances the clock while light before it delays the clock — so eastward plans seek morning light and avoid late-evening light, while westward plans seek evening light and avoid early-morning light. The page is honest that this is general evidence-based guidance and not medical advice: the times are approximate, individual responses vary with age, chronotype, sleep debt and light control, and users should consult a doctor before using melatonin or following any plan if pregnant, taking medication, or living with a sleep, mood, eye or heart condition. The clock-free engine does all arithmetic in the browser, the plan is copyable as plain text, nothing is uploaded, and the page works offline after first load.