You land in a new time zone, and your body feels like it's still somewhere over the Atlantic. You're hungry at 3 a.m., exhausted at 4 p.m., and your brain is wrapped in cotton. The question I get most from friends and readers is simple: how long does jet lag last? The honest answer is that it depends on how many time zones you crossed, which direction you flew, and how well you sleep on the plane. But there are some reliable numbers that can help you plan your recovery.
The basic rule of thumb: one day per time zone
Most sleep researchers agree that your body adjusts at a rate of about one time zone per day. If you fly from New York to London, that's five hours of difference, so expect roughly five days of feeling off. Cross the Pacific from Los Angeles to Tokyo, and you're looking at eight or nine days. That's the average, not a promise. Some people snap back in half that time, especially if they're young or already well rested. Others, like me, drag it out to the full week and then some.
I remember flying from Chicago to Rome a few years ago. Seven hours ahead. I thought I could beat the system by staying up until 10 p.m. local time on day one. I did, barely. But by day three, I was still waking up at 4 a.m. and crashing at 7 p.m. It took six full days before I slept through the night without a 2 a.m. snack break. That matched the one-day-per-zone rule almost perfectly.
Why direction matters more than distance
Flying east is harder than flying west. That's not a myth. When you travel east, you're asking your body to go to sleep earlier than it wants to, which fights your natural circadian rhythm. Westward travel means staying up later, which most people find easier. A flight from New York to Los Angeles (three hours west) might only cost you a day or two of grogginess. A flight from New York to London (five hours east) can take a full week. I've done both, and the difference is real.
If you're planning a trip and want to know exactly how many days you'll be wandering around like a zombie, try our jet lag calculator. It takes your route and flight times into account, not just the time difference. That can save you from overestimating or underestimating the recovery period.
What makes jet lag last longer
Some habits make it worse. Alcohol on the flight feels like it helps you sleep, but it fragments your sleep and dehydrates you. Caffeine close to landing can keep you wired past your new bedtime. And staying indoors all day in the hotel room tells your brain nothing about the new sun schedule. I've learned that the hard way, especially on business trips where I'd spend hours in conference rooms and then wonder why I couldn't sleep at midnight.
Another factor is your pre-trip sleep debt. If you're already running on six hours a night before you fly, jet lag piles on top of that. The first thing I do now is check my baseline with a sleep calculator and make sure I'm not starting the trip in a hole. It sounds small, but a couple of good nights before you fly can shorten your jet lag by a day or two.
How long does jet lag last for different types of trips
Here's a rough breakdown based on my own experience and what sleep experts say:
- Short haul, 2 to 3 time zones: 1 to 2 days. You might feel a bit foggy, but a good night's sleep usually fixes it.
- Mid haul, 4 to 6 time zones east: 3 to 5 days. This is where the one-day-per-zone rule really holds.
- Long haul, 7 to 9 time zones west: 4 to 6 days. Westward is gentler, but the sheer distance still takes a toll.
- Long haul, 7 to 9 time zones east: 6 to 9 days. This is the worst case. Plan for a week of being off.
Those numbers assume you're trying to adjust to the local schedule. If you're only staying for two days and then flying home, your body might never fully adapt. That's fine for a quick work trip, but don't expect to feel great.
What actually speeds up the process
Light is the biggest lever. Get outside in the morning if you flew east. Get outside in the afternoon if you flew west. Your body uses light to reset its internal clock, and morning light is especially powerful for shifting earlier. I bring a sleep mask and earplugs, but I also force myself to take a short walk outside within an hour of waking up, even if I'm exhausted. It's not fun, but it works.
Naps are tricky. A 20-minute nap can revive you without ruining your night. A two-hour nap will undo all your progress. I set a timer on my phone and stick to it. If you want to plan naps around your flight and arrival, the nap calculator on our site can show you the optimal window, which is a lot better than guessing.
Melatonin helps some people, but timing matters. Taking it at 3 p.m. local time when you're trying to stay awake is pointless. The standard advice is to take a small dose (0.5 to 3 mg) about an hour before your target bedtime. I use it only for the first three nights, then let my body take over. It's not a magic pill, but it can knock a day or two off the timeline.
Also, watch your caffeine. That 4 p.m. coffee that got you through the afternoon will still be in your system at 10 p.m. Caffeine has a half-life of about five to six hours, meaning half of it is still active after that time. If you want to know when to cut yourself off, check the caffeine half-life guide I wrote. It's helped me avoid the classic mistake of being exhausted but unable to sleep.
When jet lag feels like it never ends
Sometimes you're past the expected recovery window and still feel off. That can happen if you're flying back and forth frequently, or if you have an irregular sleep schedule at home. My rule is to give it two days beyond the one-day-per-zone estimate. If I still can't sleep after that, I start looking at other factors, like stress, poor sleep habits, or even sleep apnea. Jet lag isn't an excuse to ignore ongoing sleep problems.
For frequent travelers, the best strategy is to build a routine. I use a combination of our free sleep tools to track my sleep debt and cycle timing before and after trips. It sounds nerdy, but it's made a huge difference. Instead of guessing how I'll feel, I know exactly when to push through and when to give in to a nap.
The bottom line from someone who's been there
Jet lag lasts about one day per time zone, more if you're flying east, less if you're flying west. It's not a permanent condition, and it's not something you just have to suffer through. Get light at the right time, keep naps short, and be careful with caffeine and alcohol. And if you're planning a big trip, spend five minutes with a sleep cycle calculator to figure out your best sleep and wake windows once you land. That little bit of planning can turn a week of misery into a day or two of mild fogginess.
I still remember the first time I flew to Tokyo. I thought I could just power through. I couldn't. I spent two days wandering around Shinjuku at 5 a.m. because my body was convinced it was noon. Now I know better. I plan for the recovery, and I get back to normal in half the time. That's the difference between letting jet lag run your trip and running it yourself.