Jet Lag Planner

Flying East vs West: Why East Wrecks You and West Doesn't

Fly west to Los Angeles and you can roll straight into a late dinner, more or less human by the second day. Fly home east on the same route and you're a wreck for a week: wide awake at 3am, then fading into your lunch. Same distance, same number of time zones, a wildly different amount of suffering. It's tempting to blame yourself or the airline food, but the direction of travel is the real culprit, and once you understand why, you can plan around it instead of just bracing for it.

Your body clock would rather stay up late than get up early

One fact explains most of this. Left completely alone, with no clocks and no daylight, your body clock doesn't keep a tidy 24-hour day. It runs a touch long, nudging you to bed a little later every night, never earlier. You know the feeling already: staying up an extra hour is easy, and dragging yourself out of bed an hour early is misery.

Put that on a plane. Fly west and you ask your clock to do the easy thing, stretch the day out and go to bed later. Fly east and you force the hard thing, cut the day short and sleep before your body is anywhere near ready. West goes with the grain; east fights it. That single asymmetry is why the trip that flattens you is almost always the eastbound one.

It gets a little worse for east, because the two directions don't even recover at the same speed. The CDC puts the average rate of adaptation at about 1.5 hours a day flying west and about 1 hour a day flying east. You've probably heard that jet lag lasts about a day per time zone. It's a fine rough guide, but it hides this gap. West usually beats it, east usually misses it, and now you know why. The same asymmetry survives when you time your light properly: with the seek-and-avoid windows handled well, the clinical protocols put you at roughly 2 hours a day delaying and 1.5 advancing. Better numbers, same lopsidedness.

What each direction actually feels like

The symptoms give the direction away, which is oddly reassuring once you can name them, because you stop worrying that something is wrong with you. Fly east and you'll lie in bed wide awake at a perfectly sensible local bedtime, then need a crane to get you upright in the morning; the trouble is falling asleep. Fly west and it flips. You drop off fine, then snap awake at 4am with your whole body convinced it's morning, because back home it is. That 4am wake-up is the single most common complaint after a westbound trip, and it's completely normal for the first few nights while your clock catches up.

What to do about each direction

Light is the strongest tool you have, and the timing flips depending on which way you flew. Both plans hang off your body's daily low point, the groggy trough that lands about three hours before your usual wake-up time. (If that idea is new, Your Body Clock: Circadian Rhythm and the Temperature Minimum walks through it.)

Flying east, you're shifting earlier, so chase bright light in the morning once that low point has passed, and avoid it late in the evening. If you can, start nudging your bedtime earlier a few days before you leave. One caveat worth knowing, because it catches people out: on very large eastward jumps, the morning light at your destination can land too early and push your clock the wrong way, which is the whole reason the counterintuitive approach in Shifting the Long Way Round for Big Eastward Trips exists.

Flying west is gentler and more forgiving. Get light in the late afternoon and evening, keep the early morning dim (sunglasses on the walk to breakfast, curtains shut when you wake too early), and let your bedtime drift later in steps. West mostly sorts itself out, as long as you don't collapse into a nap at 5pm.

Is east always worse? Not for everyone

East is the harder direction for most travellers, but that's a population average, not a law, and your own wiring tips it. Morning types tend to have an earlier temperature low point, which is why the clinical protocols expect them to handle eastward flights better than most; evening types have a later one and tend to do better going west. So if you're a natural night owl you'll often shrug off westbound trips and struggle badly going east, and if your last trip didn't match the "everyone hates flying east" line, you're probably just sitting on the other side of the average rather than doing anything wrong. Larks and Owls: How Your Chronotype Changes the Plan helps you work out which one you are.

Fun fact

In 1972, a French scientist named Michel Siffre shut himself in a Texas cave for 205 days with no clock and no daylight, partly to watch this exact effect. His body refused to keep 24-hour days. It stretched them, sometimes to nearly double, drifting later and later until he lost the date completely: when the team came to fetch him on 5 September, he was convinced it was still mid-August. That built-in pull toward later is the same quirk that makes whichever leg of your trip runs eastward the crueller one.

How the Jet Lag Planner handles this

The Jet Lag Planner builds this asymmetry in for you. It reads which way you're flying and how far, applies the slower "shift earlier" pace going east and the quicker "shift later" pace going west, then hands you day-by-day windows for when to get light and when to avoid it. For a hard eastbound haul like Jet Lag From New York to London it front-loads the difficult work early; for the easy ride home it mostly points you at the evening sun. The day counts are population averages, so treat them as a solid estimate rather than a promise.

Sources

General wellness information, not medical advice. Talk to a clinician before changing your schedule if you have a sleep or health condition.

Last reviewed August 5, 2026.

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General wellness information, not medical advice. Talk to a clinician before changing your schedule if you have a sleep or health condition. © 2026 XOR Limited.