You land after a long flight, and your body insists it's 3 a.m. when the local clock says noon. That foggy, hungry-at-the-wrong-time, can't-keep-your-eyes-open feeling is jet lag. The question I get most from friends and readers is simple: how long does jet lag last? The honest answer is that it depends, but there are patterns you can count on. For most people, jet lag lasts about one day per time zone crossed, but that rule shifts depending on which direction you fly.
Why eastbound flights hit harder
Flying east means you lose time. Your body has to go to bed earlier than it wants, which is harder for most of us than staying up later. If you cross five time zones flying from New York to London, expect about three to five days of real jet lag. Flying west, say from London to New York, your body needs to stay awake longer. That's easier for most people, so recovery often takes just two or three days for the same number of zones. The worst cases are flights that cross more than eight time zones, like the US to Asia. That can take a full week or more to shake.
I once flew from San Francisco to Tokyo and felt off for six days. My sleep was broken, my appetite was weird, and I kept wanting lunch at midnight. I used a jet lag calculator before that trip, and it helped me plan light exposure. Still, my body took its sweet time adjusting. That's normal. Your internal clock can only shift about one to one and a half hours per day, no matter how determined you are.
What makes jet lag worse
Not all jet lag is created equal. A few things can stretch the misery out. Alcohol and caffeine around your flight mess with your sleep quality. So does sitting still for hours. But the biggest factor is how quickly you start following local time. If you nap for four hours at 5 p.m. because you're exhausted, you'll reset slower. I've done that. It feels good in the moment, then you're awake at 2 a.m. staring at the ceiling.
Another thing that matters is your usual sleep schedule. If you're already sleep-deprived before you fly, jet lag hits harder and lasts longer. I've learned to bank some extra sleep in the days before a long trip. It's not a cure, but it gives you a buffer. You can also use a sleep calculator to figure out your ideal bedtime and wake time before you go. That way you know your baseline and can adjust gradually.
How to shorten jet lag
You can't fully skip jet lag, but you can trim a day or two off it. The most effective tool is light. Get sunlight in the morning if you flew east, and in the late afternoon if you flew west. Light tells your brain to shift its clock. I bring a sleep mask and earplugs on every flight so I can sleep when the plane is dark, even if it's daytime outside. That small habit has made a big difference.
Melatonin can help, but timing matters. Taking it at the wrong hour can make you groggy or shift your clock the wrong way. I take a low dose about an hour before local bedtime for the first three nights. It's not magic, but it nudges me in the right direction. Also, eat meals at local times, even if you're not hungry. Your gut has its own clock, and feeding it on the new schedule helps your whole body sync up.
If you need to nap, keep it under 30 minutes and before 3 p.m. local time. A short nap can refresh you without stealing your nighttime sleep. I also use a nap calculator to time my naps so I don't wake up groggy. It sounds fussy, but it works.
When jet lag lasts longer than a week
Sometimes jet lag lingers beyond the usual window. If you're still foggy after ten days, something else might be going on. Dehydration, poor sleep on the plane, or an irregular schedule at your destination can all prolong the symptoms. I once had jet lag that lasted nine days after a trip to Australia, and it turned out I was also fighting a mild cold. So don't blame everything on time zones.
Shift work or frequent travel can also make your body clock permanently confused. In that case, you need a more structured approach. Using free sleep tools like a sleep diary or a sleep cycle calculator can help you spot patterns you'd otherwise miss. I track my sleep for a week after any long trip. It shows me whether I'm truly adjusting or just running on adrenaline.
One more thing to watch is caffeine. I love coffee, but drinking it after 2 p.m. local time can push your bedtime back and make jet lag worse. I switch to herbal tea in the afternoon for the first few days. It's a small sacrifice that pays off. If you want to know exactly when your coffee is out of your system, you can check your caffeine half-life with our calculator. That's helped me time my last cup better.
The bottom line on jet lag duration
So, how long does jet lag last? For most trips, expect two to five days. For extreme crossings, give yourself a full week. The exact number depends on your direction, your habits, and how strict you are about local time. I've learned to stop fighting it. I plan for a slow first day, get outside early, and accept that my body needs time. That acceptance actually makes it easier. The fog lifts a little more each day, and by the end of the week, I'm usually back to normal. If you're planning a trip, try our sleep calculators to map out your sleep schedule before you fly. A little prep goes a long way.