Jet lag
How Long Does Jet Lag Last?
Jet lag usually lasts about one day for every time zone you cross. That is the American Academy of Sleep Medicine's rule of thumb for how long the body clock takes to fully adjust to local time [2]. The CDC's travel guidance is a little more precise: on average, the body adapts by about 1.5 hours a day after flying west and about 1 hour a day after flying east [1]. So a 5-hour jump east takes roughly five days to settle, and the same jump west more like three or four.
Short answer: about a day per time zone
Your body clock doesn't leap into a new time zone. It creeps, an hour or so a day, nudged along mainly by daylight. Until it catches up, it keeps telling you to sleep, eat and wake on home time. That gap is jet lag, and it shrinks a little every day.
The Sleep Foundation describes symptoms lasting about 1 to 1.5 days per time zone crossed, while stressing that this varies with the person and the trip [3]. Jet lag can start once you cross two or more time zones [2], and at least mild symptoms are common when you cross more than three [3]. A long north-south flight that stays in the same time zone may leave you tired, but it won't give you jet lag [3].
Recovery times for common routes
The table uses the CDC's average rates of about 1 hour of adjustment per day going east and 1.5 hours per day going west [1]. Read the numbers as rough estimates of how long full adjustment takes, not a promise of how you'll feel on any given day.
| Route | Body clock shift | Outbound | Return |
|---|---|---|---|
| New York to London | 5 hours | About 5 days (east) | About 3 to 4 days (west) |
| New York to Paris or Rome | 6 hours | About 6 days (east) | About 4 days (west) |
| Los Angeles to London | 8 hours | About 8 days (east) | About 5 to 6 days (west) |
| Los Angeles to Tokyo | 7 to 8 hours later* | About 5 days (west) | About 7 to 8 days (east) |
| New York to Tokyo | 10 to 11 hours later* | About 7 days (west) | About 10 to 11 days (east) |
| Any 12-hour difference | 12 hours either way | About 8 days if the clock shifts later, about 12 if it shifts earlier | |
*Tokyo is many hours ahead on the clock, but flying west across the Pacific, the shorter way for the body clock to go is later, so the table assumes it shifts that way. The ranges reflect daylight saving time in the US; Japan doesn't change its clocks.
Outbound versus return: why the numbers differ
Look along any row and you'll see the two legs of the same trip rarely match. Direction is the reason. The CDC notes that adapting after a westward flight is easier than after an eastward one [1], so a US to Europe trip tends to be harder on the way out, while a US to Asia trip tends to bite on the way home. The biology behind that is a story of its own, told in our guide to whether jet lag is worse flying east or west.
Symptoms and how they fade
Jet lag can bring poor sleep, daytime sleepiness, foggy thinking, a general unwell feeling and stomach upsets, and these usually show up within a day or two of arrival [1]. The Sleep Foundation describes a common pattern: you sleep well the first night out of sheer exhaustion, then hit sleep problems over the next few nights [3].
It helps to tell jet lag apart from plain travel fatigue. Long flights wear you out in their own right, and the two share symptoms but have different causes [5]. Travel fatigue doesn't involve your body clock at all, and it usually clears after a good night's sleep, while jet lag can hang on for days until your internal clock lines up with local time [3].
Your own timeline may differ. Older adults are more likely to get severe jet lag and may need much longer to recover, and some people simply adjust faster than others [2].
What shortens jet lag
The single biggest saving comes before you leave. Shifting your sleep by 1 hour a day for the 2 to 3 days before departure, earlier for eastward trips and later for westward ones, can reduce the adjustment you face on arrival [1]. In one lab study, moving sleep an hour earlier each day for three days, with bright light in the morning, advanced the body clock by about 1.5 to 2 hours, against just over half an hour in ordinary dim light [4]. At roughly an hour of catch-up per day after an eastward flight [1], a head start like that could trim a day or two off your recovery.
Once you land, daylight is your friend. Getting outside during the day at your destination helps your clock shift [2], although the time of day matters, and our guide to how much morning sunlight you need covers how long to stay out. For a very short trip of about 2 days or less, it may be easier to stay on home time as much as you can rather than adjust at all [1]. And try to set off rested, since poor sleep in the days leading up to a flight can make you more prone to jet lag [3].
Light and sleep timing work best as a plan built around your exact flights. The jet lag calculator turns your trip into a day-by-day schedule.
When it isn't jet lag
Jet lag is temporary, and most people get over it on their own [2]. If your sleep is still off well past the window in the table, something else may be going on. Doctors only call it jet lag disorder when the sleep problem isn't better explained by another sleep disorder, a medical, neurological or mental health condition, a medication or substance use [1]. Consider seeing a sleep doctor if you travel often and keep struggling, or if you suspect another sleep disorder such as sleep apnea [2].
Count the time zones and allow about a day for each, a bit less when you fly west. If you are still struggling well past that, it's worth a word with a doctor.
Frequently asked questions
How long does jet lag last with a 12-hour time difference?
Roughly 8 to 12 days for a full adjustment. With a 12-hour difference, your body clock can shift either way. Using the CDC's average rates, moving it 12 hours later takes about 8 days and moving it 12 hours earlier about 12 [1]. These are averages, so your own recovery may be a little faster or slower.
How long does jet lag last from the USA to the UK?
From the East Coast to London is a 5-hour jump eastward, so expect about 5 days for your body clock to fully adjust [1][2]. From the West Coast it is 8 hours, or about 8 days. The trip home, flying west, is usually a little faster: roughly 3 to 4 days from London to New York at the CDC's westward rate [1].
How long does jet lag last from Japan to the USA?
Flying home from Tokyo usually means moving your body clock earlier by about 7 to 8 hours for the West Coast and 10 to 11 hours for the East Coast, which is the harder, eastward-style direction. At about an hour a day [1], that works out to roughly 7 to 8 days for the West Coast and 10 to 11 days for the East Coast.
Why do I feel fine the first night and then worse?
Many people sleep well the first night after a long flight simply because they are worn out, then run into sleep problems over the following days [3]. That first good night is your body paying off travel fatigue. It doesn't mean the jet lag is over.
Sources
- CDC Yellow Book (Riedy SM, Williams SG). Jet Lag Disorder (2025)
- American Academy of Sleep Medicine (sleepeducation.org). Jet Lag Sleep Disorder
- Sleep Foundation. Jet Lag: Symptoms, Causes, and Prevention
- Burgess HJ et al., Journal of Biological Rhythms. Preflight Adjustment to Eastward Travel: 3 Days of Advancing Sleep with and without Morning Bright Light (2003)
- Waterhouse J et al., The Lancet. Jet lag: trends and coping strategies (2007)
This page is general information, not medical advice. Sleep needs vary; if you have persistent insomnia, loud snoring, pauses in breathing or daytime sleepiness that affects your safety, see a doctor.