Why timing matters

Your internal clock

Your body follows a daily rhythm of roughly 24 hours, kept by your body clock. When you cross time zones, local time changes at once, but your clock adjusts only gradually. Jet lag is the gap between the two.

Read about your body clock

Light can move your clock

Bright light in the hours after your body's lowest temperature point tends to move your clock earlier. Light in the hours before it tends to move your clock later. The changeover is not an exact line. Light at the wrong time can move your clock the wrong way. That's why your plan sometimes asks you to avoid light.

Read about light

Shifting before you fly

Before departure, your plan may move sleep and light timing towards your destination's time.

Read about sleep

Caffeine, carefully timed

Caffeine can help alertness but lingers for hours, so your plan places specific servings and caffeine-free stretches around sleep. If caffeine is ruled out for you, the plan works without it.

Read about caffeine

How long it takes

It varies from person to person, and some clocks shift more slowly than others. Your plan shows an expected date when it can estimate one, and tells you when that estimate is uncertain. Treat the date as an estimate, not a deadline.

Read about your plan

While you travel

Your plan brings your flights, sleep opportunities and light guidance together, including time spent between flights.

Read about travel days

Where the evidence comes from

The research includes laboratory studies, studies of travellers and reviews of the evidence. These answer different questions, and do not all tell us what will happen on your trip.

Explore the sources

When to speak to a clinician

Some health conditions and medicines need extra care when planning sleep, light or caffeine. ChronoFlow's screening cannot replace a clinician's advice.

Read the health cautions