Baby jet lag, the short version
A baby's body clock shifts at roughly one hour per day. Cross six time zones, budget about six days before they're sleeping on local time without a fight. The direction you're flying decides how rough those days feel: flying east means bedtime has to move earlier — you're asking a toddler to fall asleep before their body has produced the melatonin for it, which is the hard direction. Flying west means bedtime moves later, and babies are naturally good at staying up past their bedtime once, so it's the easier direction. Everything below is the reasoning behind the calculator at the top of this page, which does this math against a real flight and a real bedtime instead of a rule of thumb.
How to use the calculator
Pick your home time zone, your destination time zone, and your baby's usual bedtime. It works out the offset, picks a direction, and builds a night-by-night bedtime target that walks from "home bedtime, converted to local time" toward the destination's normal bedtime, one hour per night. Every suggested bedtime stays inside a sane evening window — 5:30 PM to 9:30 PM local — because a "correct" bedtime of 1:30 AM is a math artifact, not a bedtime. When the raw shift would land outside that window, the plan pins to the nearest edge and tells you so, instead of quietly suggesting something no baby will do.
Eastward: New York to Rome (+6 hours)
This is the hard direction, so let's do the ugly one first. New York to Rome is a 6-hour jump forward. Home bedtime is 7:30 PM New York time — which, the moment you land, is already 1:30 AM Rome time. That's the starting point the plan works from: not "start the clock over," but "here's literally where your baby's body currently thinks bedtime is, in the new time zone."
Getting from 1:30 AM to a normal 7:30 PM takes 6 hours of shift, moving earlier by about an hour a night. For the first several nights, "an hour earlier than 1:30 AM" is still deep into the middle of the night — nowhere near a real bedtime — so the plan clamps those nights to 9:30 PM, the latest edge of the window, and flags that your baby may resist and fight it. That's not the plan failing; that's the plan being honest about what a 6-hour eastward jump actually costs you.
| Night | Raw shifted bedtime | Suggested bedtime (Rome local) | Note |
|---|---|---|---|
| 1 | 12:30 AM | 9:30 PM | Clamped — raw value is far outside the evening window |
| 2 | 11:30 PM | 9:30 PM | Clamped |
| 3 | 10:30 PM | 9:30 PM | Clamped |
| 4 | 9:30 PM | 9:30 PM | Raw value reaches the window edge |
| 5 | 8:30 PM | 8:30 PM | Back inside the normal window |
| 6 | 7:30 PM | 7:30 PM | Offset is zero — baby is on local time, plan ends |
Notice the first four nights all show 9:30 PM even though the underlying math is different each time. That's intentional — the number on nights 1 through 3 is meaningless as a bedtime target, so the plan doesn't pretend otherwise. What actually happens on those nights is daylight and tiredness doing more work than the clock, which is why the "first 48 hours" section below matters as much as the table does.
Westward: London to New York (−5 hours)
Now the easy direction. London to New York is 5 hours back. Home bedtime is 7:30 PM London time, which lands you in New York at 2:30 PM local — early afternoon. The shift moves bedtime later by about an hour a night: 2:30, 3:30, 4:30... The first three of those get clamped to 5:30 PM, the earliest edge of the window, because nobody's putting a baby to bed at 2:30 in the afternoon. By night four the raw math lands right at 5:30 PM on its own, and by night five or six you're at a completely normal 6:30–7:30 PM bedtime.
Why westward is easier in practice, not just on paper: staying up an extra hour or two is something babies already do all the time — a late car ride, an exciting evening, a skipped nap. Falling asleep an hour before their body is ready is a much harder ask, and that's the entire reason east is the direction people dread.
Before the flight
You don't need to fully pre-adjust — you can't shift six hours in three days without misery, and you shouldn't try. What's worth doing: for the 2–3 days before you fly, nudge bedtime 30–60 minutes in the direction you're about to travel — earlier for eastbound, later for westbound. It takes the edge off the first couple of nights without turning your household upside down over a trip that hasn't started yet. If it doesn't happen because life got in the way, skip it — it's a head start, not a requirement.
The first 48 hours
Light is the strongest signal you have, stronger than the clock. Flying east, get your baby into bright morning light as early as you reasonably can each day — outside, not through a window. Flying west, do the opposite: hold off on morning light and get outside in the afternoon and evening instead. This does real work even on the nights your bedtime is pinned to a clamp edge.
Keep feeds and naps roughly on the plan's clock rather than the old one — don't chase precision. Expect a 3 AM party for a night or two; that's normal, not a sign anything's wrong. Keep the room dark and boring, no lights, no screens, minimal talking — you're not trying to end the wake-up in five minutes, you're trying not to teach your baby that 3 AM is fun.
Naps during adjustment
Naps are the lever that makes or breaks whether bedtime pressure actually builds by the time the clock says it's time to sleep. Protect the last wake window of the day — don't let a late, long nap eat the sleepiness you're counting on for bedtime. If a nap is running late and bedtime is approaching, cap it rather than letting it run. A slightly short, slightly cranky evening beats a baby who's wide awake at a bedtime the plan worked hard to earn.
When it doesn't follow the plan
It won't, not perfectly. The plan is a rail to hold onto, not a contract your baby signed. Some nights will run early, some late, some will fall apart because a molar picked that week to come in. If a night blows up, don't force the next night to catch up two hours at once — pick the plan back up wherever it says you should be and keep going. The direction and the roughly-an-hour-a-day pace matter more than hitting any single night's number exactly.
Short trips: sometimes the best plan is no plan
If the trip is under about three days and the offset is three hours or less, seriously consider not adjusting at all — keep your baby on home time and just work meals and naps around it. A weekend trip isn't long enough to make the adjustment worth the disruption twice (there and back), and re-shifting for the flight home right after you finally settled in is its own kind of miserable. Save the shift plan for trips long enough to actually benefit from it.
Honest limits
This is a rate-of-shift model, not a guarantee. It doesn't know about ear pain from the flight, teething, illness, or a baby who's just having a hard week — none of that shows up in a time zone calculation. Some babies adjust faster than one hour a day, some slower; age, temperament, and how disruptive the travel itself was all matter more than the math can capture. Treat the plan as a starting point you adjust in real time, not an instruction manual. This isn't medical advice — for a sleep problem beyond travel adjustment, or anything health-related, talk to your pediatrician.
Why this exists
I built the jet-lag feature in this app during 34 days in Italy with my toddler — six time zones from home, doing exactly this math by hand at 4 AM more than once. The app now automates the part I was doing on a notepad: it detects the time zone change from your baby's actual logged sleep and builds this day-by-day plan against their real bedtime and real history, not a generic average.
Frequently asked questions
How long does baby jet lag last?
Roughly one day per hour of time difference, as a starting estimate. A 3-hour change is often mostly resolved in 3–4 days; a 6-hour change more like 5–7. That's an average pace, not a promise — some babies land closer to local time faster, especially on shorter trips or westward flights.
Is jet lag worse going east or west for babies?
East is harder. Flying east means bedtime has to move earlier, which means falling asleep before the body is naturally ready to — a hard ask at any age. Flying west means bedtime moves later, and staying up later than usual is something babies already do without much trouble. Same number of time zones, noticeably different experience depending on direction.
Should I wake my baby from a nap after a flight?
Generally, cap it rather than let it run long, especially late in the day. A nap that runs too long or too close to bedtime eats the sleep pressure you need for that night's bedtime to actually work. You don't need to cut naps short across the board — just watch the last one of the day.
Do babies adjust faster than adults to a new time zone?
Not reliably, and there's no solid basis for claiming they do. What's true is that babies' schedules are more exposed — naps, bedtime, and wake-ups are all visible and timed, so their adjustment is easier to see (and easier to feel, at 3 AM) than an adult's.
What's the fastest way to help a baby adjust to a new time zone?
Morning daylight if you flew east, afternoon/evening daylight if you flew west, plus keeping feeds and naps roughly anchored to the new local clock from day one rather than easing in. Light is doing more of the work than anything else on this list.
Should I keep my baby on home time for a short trip?
For trips under about three days with an offset of three hours or less, often yes — it's usually less disruptive than adjusting twice (once for the trip, once for the flight home). Longer trips or bigger time changes are worth actually shifting for.
Will my baby's sleep schedule go back to normal once we're home?
Yes, the same way it adjusted going out — about an hour a day, direction reversed. The trip home is jet lag again, just pointed the other way, and the same daylight and bedtime-shift approach applies.