Guides · Updated 27 July 2026

Jet Lag from the USA to Australia

Fly from Los Angeles to Sydney and something strange happens: you take off on a Monday night and land on Wednesday morning, seemingly skipping a whole day. You didn't lose time in any real sense — you crossed the International Date Line. Understanding what actually shifted is the key to recovering from it.

The Date Line, and why the calendar jumps

The confusing part of the US–Australia trip is the date, not the jet lag. The International Date Line runs roughly down the middle of the Pacific, and crossing it westbound rolls the calendar forward a day. So a flight of around 14–15 hours from the US west coast can leave on one date and arrive two calendar days later. The day isn't gone; the clock on the wall has simply wrapped around.

What matters for your body is the true time difference, and that's smaller than the calendar drama suggests. Sydney is generally about 17–19 hours ahead of Los Angeles depending on daylight-saving on both sides. But here's the crucial trick: a shift of, say, 18 hours forward is really the same clock position as 6 hours backward. Your body clock takes the shortest path — so rather than a monstrous 18-hour adjustment, it behaves much more like a manageable westward shift of a few hours plus a day change.

Not sure how many zones you're really crossing? Enter your actual cities and date into the Recovery Plan calculator — it works out the true shift and direction for you, Date Line and daylight-saving included, so you don't have to do the mental arithmetic.

So is it east or west?

This is where people tie themselves in knots. Geographically you fly west across the Pacific, and in body-clock terms the US-to-Australia trip generally behaves like a westward-style shift once the Date Line is accounted for — which is good news, because westward adjustments (the clock moving later) tend to be a little easier than eastward ones. Many travellers find LA-to-Sydney genuinely less punishing than London-to-Sydney, despite the intimidating flight time. The return trip, Australia back to the US, is the eastward-feeling leg and often the tougher half.

Because the maths is genuinely counter-intuitive here, it's worth letting a tool settle it rather than guessing. The direction determines everything about your light strategy, and getting it backwards is the most common way to make jet lag worse instead of better.

A behaviour-based plan for landing in Australia

Assuming your tool confirms a westward-style shift, the general aim on arrival is to lean your day later and to use evening light to help hold your clock back, while being careful not to fall asleep too early. The classic failure mode on this route is landing in the Sydney morning, feeling shattered, and going to bed at 5pm — which almost guarantees a 2am wake-up. A more reliable approach is to push through to a sensible local bedtime, using daylight and activity to stay upright, with at most a short early-afternoon nap of 20–30 minutes if you're really flagging.

Everything else follows the usual pattern: eat at local Australian meal times to reinforce the new rhythm, stay well hydrated after the long dry flight, and get outside during the day so your clock has strong, unambiguous cues about the new schedule. Our Light & Sleep Timing tool gives you the specific windows to seek versus avoid bright light for your direction and number of zones.

On the flight over

These flights are often scheduled to help you: many depart the US in the evening, so the natural move is to sleep for a big chunk of the crossing and wake up oriented toward Australian daytime. Set your watch to Sydney at the gate, sleep when it's night there, and stay awake and lit when it's day there. Hydrate steadily, go easy on alcohol, and get up to move periodically. The In-Flight Sleep Planner maps this onto your exact departure time and flight length.

Coming home to the States

The eastbound return crosses the Date Line the other way — you can land the "same day" you left — and in body-clock terms it usually feels like the harder, eastward-style adjustment. On the way home, morning light and an earlier schedule are generally the helpful direction. Give yourself a little more grace on the return; it's normal for it to take longer to settle than the trip out did.

For anything you take — including melatonin — consult your doctor or pharmacist. This site does not give medical advice.

Let the tool do the Date Line maths. Put your real cities and dates into the Recovery Plan and it will tell you the true shift, the direction, and your day-by-day windows. See all calculators →

This is a guide — check what works for your own situation, and consult a professional if you're unsure.