How do I avoid jet lag on long flights?

Jet lag is a mismatch between your body’s internal clock and the local time at your destination. The CDC Yellow Book explains that it is worse the more time zones you cross and is usually worse heading east than west, because the body finds it harder to advance its clock than to delay it. Symptoms include daytime sleepiness, trouble sleeping at night, reduced concentration, digestive issues, and general malaise. There is no way to eliminate jet lag entirely, but the right pre-flight and in-flight habits can cut the recovery time in half.

The most important tool is light. The suprachiasmatic nucleus in the brain uses light cues to set the circadian clock, and using light at the right time can shift that clock by an hour or two per day. The Mayo Clinic and the CDC both recommend getting bright outdoor light in the morning at the destination if you flew east, and seeking light in the late afternoon or early evening if you flew west. Avoiding light at the wrong time matters just as much: if you arrive in Tokyo at 6 a.m. local time after flying east from New York, do not spend the morning in a dark hotel room catching up on sleep. Step outside, walk around, and let the morning light pull your clock forward.

Pre-flight shifting is the next layer. For a trip across six or more time zones, start moving your sleep schedule toward the destination a few days before departure. Shift by one to two hours per day in the right direction. Eastbound trips move bedtime earlier; westbound trips move it later. The CDC notes that even partial pre-adaptation can shave two to four days off recovery. Short trips, especially those under four days, often do not justify full pre-adaptation because you would just be jet-lagged at home.

Melatonin is genuinely useful for eastbound flights and flights across more than five time zones. The AASM clinical guidance and the Mayo Clinic both support taking a low dose, typically 0.5 to 3 mg, about 30 minutes before the target bedtime at the destination for several nights. Timing matters more than dose. Melatonin taken at the wrong time can shift your clock the wrong way and make jet lag worse. The NHS recommends using it for short-term travel only and not driving or operating machinery for four to five hours after taking it.

During the flight itself, hydration and movement matter. CDC and Mayo Clinic both advise drinking water regularly, wearing loose clothing, and getting up to walk the cabin every couple of hours to reduce stiffness and lower the risk of deep vein thrombosis. Avoid heavy alcohol and oversized meals, which make sleep on the plane less restorative and leave you more dehydrated on arrival. If you can sleep on the plane, set a watch to destination time and try to sleep according to the destination’s nighttime hours, even if your body says otherwise. A neck pillow, eye mask, and noise-cancelling headphones make this much easier.

Once you land, the goal is to anchor quickly. Get daylight, eat meals at destination time, and try to stay awake until a reasonable local bedtime even if you are tired. If you arrive during the day and cannot stay awake, a short 20 to 30 minute nap before 3 p.m. local time is more useful than a multi-hour sleep that locks in the old time zone. If you are arriving for an important meeting or event, the most reliable trick is simply to arrive a day early.

Caffeine and exercise both have a role, used strategically. Caffeine in the morning reinforces wakefulness for eastbound travelers but should be avoided within six to eight hours of bedtime. A 20 to 40 minute walk outside within a few hours of landing helps the body clock reset faster than indoor light. For related flight comfort issues, see the neck pain guide and the TSA PreCheck explainer.