Jet lag typically lasts about one day for every time zone you cross. Fly from Los Angeles to New York (three time zones), and you can expect roughly three days of adjustment. Cross nine time zones to reach Europe or Asia, and full recovery can stretch to one or two weeks depending on which direction you flew.
That “one day per time zone” rule is a useful baseline, but the real answer depends on several factors: the direction of travel, how many zones you crossed, and whether you actively manage your light exposure and sleep timing after arrival.
The General Recovery Timeline
Jet lag symptoms usually show up within a day or two of landing and are proportional to the distance traveled. A short hop across two or three time zones might leave you feeling off for a couple of days. A long-haul flight spanning eight or nine zones can mean well over a week before your body fully resets.
Your internal clock shifts by roughly one hour per day on its own. So if you’re six time zones away from home, your brain and body need about six days to catch up, assuming you’re getting the right light cues and not accidentally reinforcing the old schedule. Without any deliberate effort, recovery can drag out even longer.
Why Flying East Takes Longer to Recover From
Direction matters more than most travelers realize. Flying east is consistently harder on your body than flying west, and the recovery gap widens as the trip gets longer.
For a three-time-zone trip, the difference is modest: a little over four days to recover flying east versus a little under three days flying west. But for a nine-time-zone trip, eastward recovery takes roughly 14 days compared to about 8 days heading west. That’s nearly double.
The reason is biological. Your internal clock naturally runs slightly longer than 24 hours, which means it finds it easier to extend the day (as happens when you fly west) than to shorten it (flying east). Eastward travel forces you to fall asleep earlier and wake up earlier than your body wants to, which is a harder adjustment for most people.
One interesting exception: at 12 time zones (the maximum possible shift), recovery is about 10 days in either direction. At that point, your body can adjust by shifting the clock forward or backward, so the directional advantage disappears.
Symptoms Beyond Poor Sleep
Most people associate jet lag with trouble sleeping, but the disruption runs deeper. Your circadian clock doesn’t just regulate sleep. It controls digestion, hormone release, body temperature, and cognitive function. When that clock is misaligned with local time, all of those systems feel it.
Common symptoms include daytime fatigue, difficulty concentrating, irritability, and gastrointestinal issues like constipation, diarrhea, or loss of appetite. You might feel mentally sharp at 2 a.m. and completely foggy at noon. These non-sleep symptoms generally track the same timeline as the overall recovery, fading as your internal clock catches up to local time. For short trips across two or three zones, most of these resolve within a few days. For longer trips, digestive issues and brain fog can linger for a week or more.
How Light Exposure Speeds Recovery
Sunlight is the single most powerful tool for resetting your internal clock. Your brain uses light signals from your eyes to calibrate its sense of day and night, and getting bright light at the right times can make each day of adjustment more effective.
The key is timing. After flying east, you want morning light exposure at your destination to push your clock earlier. After flying west, evening light helps extend your day. Getting the timing wrong, such as exposing yourself to bright light when your body thinks it’s the middle of the night, can actually slow your adjustment or shift you in the wrong direction.
In the evenings, dimming indoor lights for about two hours before bed supports your body’s natural production of melatonin, the hormone that signals sleep. This is true whether you’re jet-lagged or not, but it’s especially useful when your clock is already confused.
How Melatonin Can Help
Melatonin supplements can nudge your clock in the right direction when timed correctly. The CDC notes that a dose of 0.5 to 1 mg is often enough to produce a circadian shift. Higher doses (above 5 mg) aren’t recommended because excess melatonin lingers in your system and can end up active at the wrong time of day, potentially making the misalignment worse.
For eastward travel, taking melatonin about 90 minutes before your target bedtime helps advance your clock, making it easier to fall asleep earlier. For westward travel, taking it when your internal clock thinks it’s morning can help delay your rhythm. The timing matters more than the dose. Taking melatonin during the window when your body is already producing it naturally (roughly midnight to 5 a.m. on your internal clock) has less effect.
Getting the timing wrong can backfire, so it helps to think about what time your body thinks it is rather than what the local clock says. If you flew east from New York to Paris and landed in the morning, your body still thinks it’s 2 a.m. Taking melatonin at that point won’t do much because your natural melatonin is already high.
Factors That Affect Your Personal Timeline
The one-day-per-zone rule is an average, and individual experiences vary. Age plays a role: older adults tend to adjust more slowly because their circadian systems are less flexible. People who already have irregular sleep schedules may find the transition either easier (because their clock is already somewhat loose) or harder (because they lack a strong rhythm to anchor to).
Arrival time matters too. Landing in the morning gives you a full day of local light cues to start the adjustment process. Landing at night and immediately going to sleep in a dark room delays those cues by several hours.
Caffeine and alcohol both interfere with recovery, though in different ways. Caffeine blocks sleepiness without actually shifting your clock, which can leave you awake at the wrong times. Alcohol may help you fall asleep initially but fragments sleep later in the night, reducing the quality of rest your body needs to recalibrate.
For trips lasting fewer days than time zones crossed (a quick two-day business trip across six zones, for example), some travelers find it easier to stay on their home time zone entirely rather than attempting a partial shift they’ll just have to reverse.