Jet Lag: Which Remedies Have Evidence and Which Are Sold by Habit

Jet lag is not a sleep problem. It is a clock problem, and the clock is in almost every cell of the body.

That distinction matters because it explains why the products sold for jet lag are so often useless. A sleeping pill can knock you out at the wrong hour. It cannot move the clock, so you wake up in the wrong time zone with the same mismatch you started with.

The direction of travel decides how bad it gets

Flying east is worse than flying west, and the reason is not psychological.

The body clock runs slightly longer than twenty-four hours, which means it is naturally good at delaying itself and bad at advancing. Westbound travel asks the clock to stay up later, which it does with some willingness. Eastbound travel asks it to go to bed earlier, which it resists.

A six-hour eastbound shift is harder than a nine-hour westbound one. Most people who have done both will tell you the same thing without knowing why, which is that the eastbound trip leaves you awake at three in the morning staring at a hotel ceiling while the westbound trip leaves you tired but functional, and the asymmetry is built into the clock rather than into the airline or the cabin.

Light is the strongest signal you have

The clock is set mainly by light hitting the retina, and the timing of that light determines whether the clock moves forward or backward.

Morning light in the new time zone advances the clock. Evening light delays it. That is the entire mechanism, and everything else is either supporting it or fighting it.

The practical version: get outside in the morning for the first two or three days, and keep the room dark in the evening. Not dim. Dark. A hotel room with a curtain that does not close is a jet lag machine, and a sleep mask costs less than a single airport coffee.

Sunlight through a window is weaker than sunlight outside, and a phone screen is not a substitute for either. If you land in the morning and go straight to a dark hotel room to nap, you have told your body it is still nighttime and it will believe you.

Melatonin, in the dose that actually gets studied

Melatonin is the one supplement with a reasonable body of evidence for jet lag, and the effective dose in most trials is small — commonly 0.5 to 5 milligrams, taken at the target bedtime in the new time zone rather than on arrival.

The larger dose is not better. It is a shelf decision, not a clinical one. Doses of 10 milligrams and above are common on store shelves because they sell a story about strength, not because they outperform a smaller dose, and the buyer who takes the biggest tablet available is paying more for a worse-tested version of the same molecule.

In the United States, melatonin is sold as a dietary supplement rather than a drug, which means the dose on the label is not verified by the Food and Drug Administration before sale. Independent testing has repeatedly found products that contain more or less than the label states. A brand that publishes a certificate of analysis is worth the extra few dollars.

Melatonin is not a sedative. Taken at the wrong hour it can shift the clock in the wrong direction, which is why the timing matters more than the pill.

Caffeine and alcohol both work, and both cost you

Caffeine is useful in the morning of the new time zone and unhelpful after about two in the afternoon, because its half-life is long enough that a four o’clock coffee is still circulating at bedtime.

Alcohol is the more expensive mistake. It shortens the time it takes to fall asleep and then fragments the second half of the night, which is the half where the body is doing the deeper work. A drink to celebrate landing is fine. Three drinks as a sleep aid is a way to arrive at the first morning of a trip already behind.

What the airport sells

The travel aisle has a category of products built on the assumption that jet lag is a deficiency.

Jet lag pills usually combine melatonin with herbs and B vitamins, at doses that are either too small to matter or unstudied. You are paying for the combination rather than for any single ingredient with evidence behind it.

Anti-jet-lag glasses are a real category with a real idea behind them, since blocking blue light in the evening can help the clock delay itself. The evidence is thinner than the marketing suggests, and a pair of amber glasses from a hardware store does the same job as the aviation-branded version at a fraction of the price.

Compression socks are worth buying for long flights, but not for jet lag. They address swelling and circulation, which is a different problem with a different mechanism.

Homeopathic jet lag remedies contain no active ingredient by definition. That is not a controversial claim; it is what the label says if you read the dilution.

The part nobody sells

The cheapest intervention is scheduling, and it starts before the flight.

If the trip is short — three days or less — shifting the clock may cost more than it saves. Staying on home time and accepting an odd schedule is a legitimate strategy for a quick business trip, and it is what many frequent flyers actually do.

For longer trips, start moving bedtime by an hour a night for the two or three nights before departure, in the direction of travel. It is not dramatic and it is not marketable, which is why it does not appear in airport advertising.

On the plane, set your watch to the destination time when you board and behave accordingly. Eat when the destination is eating. Sleep when the destination is sleeping. The flight is the first night of the new time zone, not a gap between two real days.

Where self-management stops

Jet lag is uncomfortable and self-limiting. Several things that look like jet lag are not.

If sleep does not consolidate after a week, if daytime sleepiness is severe enough to affect driving or work, or if snoring and pauses in breathing come with the travel, that is a reason to talk to a clinician rather than to buy a stronger supplement. Sleep apnea is common, underdiagnosed, and does not resolve with melatonin.

Prescription sleep medication for travel is a conversation with a prescriber, not a purchase. The same drug that helps one person on a long-haul flight can leave another person groggy at the wheel of a rental car.

A sequence that costs almost nothing

Take the flight. Set your watch on boarding. Drink water. Skip the second drink. Sleep if the destination is sleeping, stay awake if it is not.

Land, get outside before noon, and stay out for an hour. Take melatonin at the local bedtime if you want it, in a small dose, from a brand that tests its product. Keep the room dark and the coffee before two.

Then wait three days. The clock is slow, and no product on the airport shelf makes it faster.