How to Avoid Jet Lag: A Step-by-Step Plan

Jet lag happens when your internal clock is still running on home time while everything around you has already moved on. You can't flip a body clock on command, so the goal isn't to prevent jet lag completely — it's to shorten it and take the edge off.

Four things do most of the work: light, by far the strongest signal your body clock reads; when you sleep; when you eat and drink caffeine; and what you do on arrival day, which matters more than any pill or supplement.

Plan on roughly one day of adjustment per time zone crossed. A five-hour shift typically means three or four rough days, not two weeks, and the first night is usually the worst of it.

A few minutes of preparation before you book or pack makes the whole plan easier to follow:

• The exact gap and its direction. Write down the hours between home and destination, and which way you're traveling. Five hours east is a very different job from five hours west.
• Your anchor times at the destination. Decide now what a normal bedtime and wake-up time will look like there, roughly 10–11 p.m. and 6–7 a.m. for most people.
• What you actually have to do in the first 24 hours. Driving, a presentation, or wrangling small children changes how aggressive you should be with the plan.
• Anything medical. If you take regular medication, use sleep aids, or are thinking about melatonin for yourself or a child, check with a pharmacist or clinician before you travel.
• A small kit for the flight. Eye mask, earplugs, a layer you can take off, and water. These are the tools that decide whether you sleep on the plane.

Your body clock takes its main cue from light hitting your eyes. That makes light timing the single most useful thing you can control, and it's free.

Going east, you want to be ahead of local time: get bright outdoor light soon after waking, and keep evenings dim. Going west, you want to be behind: seek light in the late afternoon and evening, and protect yourself from bright early-morning sun if you're waking at 4 a.m. ready for the day.

Getting this backwards is easy and it's the most common reason a careful plan doesn't work. Sitting in a brightly lit hotel bar until midnight is the wrong move after an eastbound flight.

In-flight sleep is only useful if it lands in the right place on the clock. A three-hour hop needs no strategy. A ten-hour flight arriving in the morning is different: you want a decent block of sleep so you can stay awake through the whole arrival day.

A practical approach is to eat the first meal, then settle in for six or seven hours with an eye mask and earplugs, and set an alarm for about 90 minutes before landing so you wake up, drink water, and arrive feeling like it's morning. If you're landing in the evening instead, keep any sleep short and treat the flight as a long day.

Don't chase sleep you don't need. Lying awake with your eyes shut for eight hours is less restful than a two-hour nap plus a film, and it leaves you frustrated before the hardest part of the trip.

These three are smaller levers than light, but they're the ones people get wrong most often.

• Caffeine genuinely helps you push through an arrival day, but it has a long tail. Cut yourself off roughly six to eight hours before your target bedtime, in local time. An afternoon coffee to survive the slump can cost you the night.
• Alcohol is sedation, not sleep. It fragments the second half of the night and leaves you drier and more tired. Skip it on the flight and on the first night if you can.
• Water matters in dry cabin air, but drink steadily rather than in huge amounts at once, so you're not up and down all night in an unfamiliar room.
• Meal times are a secondary clock cue. Eating at local breakfast, lunch and dinner times — even lightly — reinforces the light signal. There's no need to fast or follow a complicated schedule; skipping meals entirely usually just makes you feel worse.

Arrival day decides how the rest of the trip goes.

• Get outside in daylight. Morning light if you came east, late-afternoon light if you came west.
• Move your body. Walking and light exercise help you stay awake and sleep better; save hard workouts for earlier in the day.
• Nap in a controlled way. If you must, keep it to 20–30 minutes and finish before about 3 p.m.
• Don't go to bed absurdly early. A 7 p.m. bedtime after a red-eye means waking at 2 a.m. and staring at the ceiling. Aim for 9–11 p.m. local and accept that you'll be tired.
• If you wake at 3 a.m., stay in bed and keep the room dark if you're calm. If you're wide awake and frustrated, get up, use dim light, avoid your phone, and go back when you feel sleepy.

Children usually adjust faster than adults but get overtired quickly, so keep their meals, naps and bedtime on local time from the first day rather than letting them crash.

• An early first bedtime. Crashing at 7 p.m. feels like the right call and guarantees a 2 a.m. wake-up. Fix: stay up to at least 9 p.m. local, even if it means walking laps around the block.
• A long arrival-day nap. A three-hour nap takes all the pressure off your bedtime. Fix: 20–30 minutes, early afternoon, alarm set.
• Getting the light backwards. Bright evenings after an eastbound flight push your clock the wrong way. Fix: dim evenings eastbound, bright evenings westbound.
• Using alcohol to force sleep. It works for an hour and backfires by 3 a.m. Fix: water and a dark room instead.
• Scheduling something important on arrival day. Your decision-making is genuinely poorer when you're sleep-deprived. Fix: keep day one light and move anything demanding to day two or three.
• Ignoring the return trip. The same rules apply in reverse when you fly home, and most people give themselves no time at all. Fix: book a quiet day after you land and repeat the light plan in the other direction.

Melatonin is a hormone that signals darkness to your body, not a knock-out pill, and it's sold as a supplement in the US, which means contents and quality vary between products. Ask a pharmacist or clinician before using it — particularly if you take other medication, are pregnant, or are considering giving it to a child.

If you have a sleep disorder such as insomnia or sleep apnea, or a medical condition affected by sleep loss, plan the trip with your clinician rather than improvising. And if you're still exhausted, low, or sleeping badly two weeks after you land, that's beyond ordinary jet lag and worth a conversation with a doctor.