Jet lag typically takes about one day per time zone crossed to fully go away. A flight from California to New York (three time zones) means roughly three days of adjustment, while a transatlantic trip spanning eight or nine time zones can leave you off-balance for over a week. In all cases, symptoms should resolve within two weeks at most.
The General Recovery Timeline
Your internal clock resets at a rate of about one hour per day, according to Harvard Medical School’s sleep research. That one-to-one ratio (one day of recovery per time zone) is the standard rule, but it’s an average. Some people bounce back faster, and others drag on longer depending on the direction they traveled, their age, and how they manage light and sleep after arrival.
For short trips crossing two or three time zones, you may barely notice jet lag or shake it off in a day or two. Cross six or more zones, and you’re looking at close to a week of disrupted sleep, daytime fatigue, trouble concentrating, and digestive issues. If your symptoms persist beyond two weeks, something else may be contributing to your sleep difficulty, and it’s worth getting evaluated.
Why Flying East Takes Longer to Recover From
About 75% of people have an internal clock that runs slightly longer than 24 hours. That means your body naturally drifts a little later each day, which is essentially the same direction as westward travel. Flying west asks you to lengthen your day, and your clock is already inclined to do that. Flying east forces you to shorten your day and fall asleep earlier than your body wants to, which works against your natural drift.
The practical difference: a westward trip across six time zones might feel manageable after four or five days, while the same trip eastward could take the full six days or longer. If you’re one of the roughly 25% of people whose clock runs shorter than 24 hours (typically morning types who naturally prefer early bedtimes), you may actually find eastward travel easier. But for most travelers, east is the harder direction.
Age Makes a Measurable Difference
Older travelers tend to have a harder time recovering. In a controlled study comparing young adults (18 to 25) with middle-aged adults (37 to 52) after a simulated eastward time shift, the middle-aged group experienced more nighttime waking, earlier sleep termination, and larger drops in alertness and well-being during the first four days. They also reported more sleepiness, weariness, and effort required to get through daily tasks. The core issue appears to be difficulty maintaining sleep when the body’s internal clock still thinks it’s too early for rest. If you’re in your 40s or older, it’s reasonable to budget an extra day or two beyond the one-day-per-zone rule, especially for eastward trips.
What Jet Lag Actually Feels Like Day by Day
The first one to two days are usually the worst. You’ll feel an intense pull toward sleep at odd hours, wide-eyed alertness in the middle of the night, and a foggy inability to concentrate during the day. Digestive symptoms like nausea, constipation, or a general loss of appetite are common in this window because your gut has its own circadian rhythm that’s also out of sync.
By days three through five, sleep timing starts to normalize. You may still wake up too early or feel an afternoon energy crash, but the extremes soften. Cognitive sharpness returns faster than sleep quality for most people. The last thing to fully realign is often deep, uninterrupted sleep through the night, which can lag behind your daytime adjustment by a day or two.
How Light Exposure Speeds Recovery
Light is the single most powerful tool for resetting your internal clock. Your brain uses light hitting your eyes to calibrate when it’s daytime, so strategic exposure (or avoidance) can cut your recovery time noticeably.
After flying east, you want morning light at your destination. Get outside early, even if you feel terrible. This pushes your clock earlier, which is exactly what eastward travel demands. After flying west, seek out late afternoon and evening light to delay your clock and extend your day. The key mistake is getting bright light at the wrong time. For example, if you flew east across eight time zones, early morning light at your destination might actually correspond to late night on your body clock, which could push your adjustment in the wrong direction. For very long trips, it helps to calculate what time your body thinks it is and plan your light exposure accordingly.
Using Melatonin Correctly
Melatonin can help, but timing matters more than dose. A small amount, 0.5 to 1 mg, is often enough to nudge your circadian rhythm. Higher doses above 5 mg aren’t recommended because the excess melatonin lingers in your system and can end up active at the wrong time of day, potentially making your adjustment worse.
For eastward travel, take melatonin about 90 minutes before your target bedtime at the new destination. This supports the natural rise in melatonin your body needs to fall asleep earlier. For westward travel, taking melatonin when your internal clock thinks it’s morning can help delay your rhythm. The critical rule: don’t take it during the hours when your body is already producing its own melatonin (roughly 12 a.m. to 5 a.m. on your body’s clock), because it won’t add much benefit and wastes an opportunity to take it at a more useful time. Taking melatonin at the wrong point in your cycle can actually increase the mismatch between your internal clock and local time.
Practical Tips That Shorten Recovery
- Shift before you leave. Moving your bedtime 30 to 60 minutes toward the destination time zone for two or three nights before departure gives your clock a head start.
- Stay hydrated and skip alcohol on the flight. Dehydration and alcohol both worsen fatigue and disrupt sleep quality, compounding jet lag symptoms on arrival.
- Eat on local time immediately. Meal timing is a secondary clock-setter. Even if you’re not hungry at local mealtimes, eating small amounts helps signal your digestive system to shift.
- Limit naps to 20 minutes. Long naps feel irresistible but delay your adjustment by relieving sleep pressure at the wrong time.
- Exercise in the morning at your destination. Physical activity reinforces the light-based signal that it’s daytime and helps consolidate nighttime sleep.
For trips shorter than three days where you’re crossing six or more time zones, some travelers find it easier to stay on home time entirely rather than attempting a full adjustment they won’t complete before flying back.