Skip to content
ENExplore Calculators

Sleep Adjustment Travel

Free Sleep Adjustment Travel calculator with clear step-by-step results.

About Sleep Adjustment Travel

The body clock shifts roughly one hour a day westward but only about two-thirds of that eastward, because advancing sleep is harder than delaying it. Pre-adapting before departure removes hours from the post-arrival adjustment, and the share-of-trip figure shows whether adapting is even worth attempting.

Formulas

Effective shift rate

Rate = achievable shift per day / 1.5 when travelling east, unchanged travelling west

Days to adjust

Days = (time zones - hours pre-shifted) / effective rate

Worked example

With the default values below, Sleep Adjustment Travel returns Days to fully adjust after arrival of 9.0. Change any input above and every figure here is recalculated in your browser.

Inputs used

Time zones crossedaccepts 1–14
8
Direction of travelone of Eastward (advancing the clock), Westward (delaying the clock)
Eastward (advancing the clock)
Length of the tripaccepts 1–90 days
7 days
Days of pre-adaptation before departureaccepts 0–14
3
Shift achievable per dayaccepts 0.25–3 h
1 h

Results

Days to fully adjust after arrival
9.0 days
Hours already shifted before flying
2.0 h
Effective adjustment rate
0.67 h/day
Share of the trip spent adjusting
100.0% %

Step by step

  1. 1Values used
  2. 2Effective shift rate
  3. 3Days to adjust
  4. 4Days to fully adjust after arrival= 9.0 days
  5. 5Hours already shifted before flying= 2.0 h
  6. 6Effective adjustment rate= 0.67 h/day
  7. 7Share of the trip spent adjusting= 100.0 %

Assumptions and limits

  • The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • General guidance only. Circadian adaptation varies substantially between individuals, and light exposure timing, melatonin and medication all affect it. Seek medical advice for shift work disorder or persistent insomnia.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

General guidance only. Circadian adaptation varies substantially between individuals, and light exposure timing, melatonin and medication all affect it. Seek medical advice for shift work disorder or persistent insomnia.

Frequently Asked Questions

Should I adapt at all for a short trip?

If adjustment would consume most of the trip, many travellers do better staying on home time for meetings and sleep. Below about three days abroad that is usually the better strategy.

Why is eastward travel harder?

The free-running human circadian period is slightly longer than 24 hours, so delaying sleep comes naturally and advancing it fights the body's own drift.

Related Calculators

Sleep Adjustment Travel | Calcrivo