The fastest way to get over jet lag is to strategically time your light exposure, sleep, and meals to reset your internal clock. Your body adjusts to a new time zone at roughly one day per hour of time difference, but the right approach can speed that up significantly. The core principle is simple: light is the most powerful signal your brain uses to set its 24-hour rhythm, and getting it at the right time (while avoiding it at the wrong time) is the single most effective thing you can do.
Why Direction Matters
Jet lag hits harder when you fly east than when you fly west. Your body’s natural clock runs slightly longer than 24 hours, so stretching the day (as westward travel does) feels more natural than compressing it. Flying west, you need to stay up later and sleep later. Flying east, you need to fall asleep earlier and wake up earlier, which works against your biology. This is why a London-to-New York flight often feels easier to recover from than the return trip.
Time Your Light Exposure
Light is the strongest tool you have. The trick is knowing when to seek it and when to block it, and that depends on a reference point called your temperature minimum. This is the moment in your sleep cycle when your core body temperature is lowest, typically about three hours before your usual wake-up time. If you normally wake at 7 a.m., your temperature minimum is around 4 a.m.
For westward travel (delaying your clock), seek bright light in the hours before that temperature minimum and avoid it in the hours after. In practice, this means getting evening light at your destination and staying away from early morning light for the first day or two.
For eastward travel (advancing your clock), do the opposite. Avoid light before your temperature minimum and seek it afterward. That means wearing dark sunglasses or staying indoors during the early morning hours at your destination (when your body still thinks it’s the middle of the night), then getting as much bright light as possible once a few hours have passed.
Outdoor sunlight is ideal, but a portable light box works too. When you need to block light, dark sunglasses, blue-light-blocking orange glasses, or simply sleeping in a dark room all count. One important detail: sleep counts as darkness for your brain. If you sleep during a window when you should be seeing light, you’ll push your clock in the wrong direction and make jet lag worse.
Use Melatonin Strategically
Melatonin works best as a clock-shifting signal, not as a sleeping pill. The CDC notes that 0.5 to 1 mg is often enough to produce a circadian shift. Higher doses (above 5 mg) aren’t recommended because the excess melatonin lingers in your system and can end up active at the wrong biological time, potentially making your adjustment slower.
For eastward travel, take melatonin about 90 minutes before your target bedtime at the destination. This reinforces your body’s natural evening melatonin rise and helps pull your clock earlier. For westward travel, the goal is the opposite: you want melatonin to hit when your internal clock thinks it’s morning, which helps push your rhythm later. In practice, this can mean taking it during what feels like the early hours at your destination.
Timing matters more than dose. A small amount at the right moment is more effective than a large dose at a vague “bedtime.”
Shift Before You Leave
You don’t have to wait until you land to start adjusting. For several days before departure, gradually move your bedtime and mealtimes closer to your destination’s schedule. Even shifting by 30 to 60 minutes per day can take the edge off. If you’re flying east, go to bed a bit earlier each night. If you’re flying west, stay up a bit later. This pre-trip shifting is especially valuable for trips crossing five or more time zones, where the full adjustment can otherwise take nearly a week.
Manage Meals and Fasting
Your digestive system has its own internal clock that responds to when you eat. Researchers at Harvard-affiliated Beth Israel Deaconess Medical Center identified a secondary “master clock” in mice that activates when food is scarce, essentially overriding the light-based clock. The theory is that humans have a similar mechanism, and a 12-to-16-hour fast before and during travel could trigger a faster reset when you eat your first meal on the destination’s schedule.
This hasn’t been tested in clinical trials, and some circadian scientists argue that food does not reset the brain’s central clock the way light does. Still, eating meals at local times once you arrive is a practical way to reinforce your new schedule, even if the fasting method remains unproven.
Nap Smart
When you’re running on broken sleep, napping is tempting, but doing it wrong can sabotage your nighttime sleep. Keep naps under 20 minutes. A short nap boosts alertness for a couple of hours without reducing the sleep pressure that helps you fall asleep at your target bedtime. Set an alarm for 15 to 20 minutes so you don’t drift into deeper sleep, which causes grogginess and makes it harder to sleep that night.
If possible, nap earlier in the day rather than later. A late-afternoon nap is the most likely to interfere with falling asleep at a reasonable hour.
Caffeine and Alcohol
Caffeine can be a useful tool in the morning to push through fatigue, and one study found that 300 mg of slow-release caffeine improved alertness on eastbound flights. But it works against you later in the day. Cut off caffeine by early afternoon at the latest. Combining afternoon caffeine with an already disrupted clock makes falling asleep at your target bedtime much harder.
Alcohol is deceptive. It may help you feel drowsy, but it fragments sleep and reduces sleep quality, which is the last thing you need when your body is already struggling to consolidate rest in a new time zone. Staying well-hydrated with water during and after the flight is a better move, since cabin air is extremely dry and dehydration amplifies fatigue.
Apps That Build a Plan for You
If timing light, melatonin, and sleep sounds complicated, jet lag apps like Timeshifter can generate a personalized schedule based on your flight itinerary, your usual sleep times, and your chronotype (whether you’re naturally a morning or evening person). The underlying algorithms were originally developed for NASA astronauts and combine timed light exposure, melatonin, caffeine, and nap recommendations into a single plan. These apps handle multi-city trips, stopovers, and flight delays, and they adjust advice to what’s actually practical rather than theoretically ideal.
A Realistic Recovery Timeline
The general rule is about one day of adjustment per time zone crossed. A five-hour shift typically takes four to six days to fully resolve without intervention. With properly timed light and melatonin, many travelers cut that roughly in half. You’ll likely feel functional within two or three days, with residual effects like early waking or afternoon fatigue lingering a bit longer.
Westward trips tend to resolve faster. Eastward trips across six or more zones are the toughest, and starting your adjustment before departure makes the biggest difference for those itineraries. The first two days at your destination matter most. Get your light timing right during that window, and the rest of the adjustment follows much more smoothly.