The guide

Melatonin for jet lag and night shifts

By GyroscopeUpdated November 14, 20267 sources

Trips are where melatonin does its best work. In 9 of 10 jet lag trials, taking it at bedtime in the new time zone reduced jet lag after flights across 5 or more time zones, at doses from 0.5 to 5 mg. Flying east is harder, since your clock moves about 57 minutes a day after flying east against about 92 after flying west. After night shifts it helps less, adding about 24 minutes of daytime sleep.

In both cases the problem is the same. Your body clock is set to one day, and your life has jumped to another. Melatonin and light are the two things that can move the clock faster than it moves on its own.

Isn’t jet lag just being tired from the flight?

That’s part of it, and it’s why people reach for a sleeping pill on the plane. But a long flight that stays inside your own time zone doesn’t leave you waking at 3am for a week.

Jet lag comes from your body’s rhythms being out of step with day and night at your destination. You land in Paris at 8am, but your body clock still says 2am in New York. It catches up, but only about an hour a day, and until it does you’re sleepy at noon and wide awake at night.

A simple way to picture it

Your body clock is like a watch that runs a few minutes slow every day. Letting it fall further behind is easy, since it’s already doing that. Making it gain time takes work.

Flying west asks your watch to fall behind. Flying east asks it to gain time. That’s why the same 6 hour trip feels so different in each direction.

What did the jet lag trials find?

In 2002 the Cochrane Collaboration, which pools trials to judge what works, reviewed 10 randomized trials of melatonin in airline passengers, airline staff and military personnel.

• 9 of the 10 trials found melatonin reduced jet lag after flights across 5 or more time zones, taken close to bedtime at the destination, 10pm to midnight.
• 0.5 to 5 mg worked about equally well, except that people fell asleep faster and slept better on 5 mg than on 0.5 mg. Doses above 5 mg did no better.
• About one in every two people who took it was helped beyond what a placebo did.
• The benefit was bigger the more zones people crossed, and smaller flying west.
• Timing mattered. Taken early in the day, melatonin made people sleepy and delayed their adjustment to local time.
• A 2 mg slow-release tablet did relatively poorly, so a short, high peak seems to work better.

The reviewers called it “remarkably effective” and said it should be recommended to adults crossing 5 or more time zones, especially flying east. They added that people crossing 2 to 4 zones could use it if they need to. Case reports suggested people with epilepsy and people taking warfarin could come to harm, so they should ask their doctor first.

Why is flying east harder?

In real travelers, the body clock moved about 92 minutes a day after westward flights and about 57 minutes a day after eastward ones. Eastman and Burgess explain why in their 2009 guide. The average human clock runs slightly longer than 24 hours when left to itself, so most people already drift a little later each day. Moving later goes with that drift. Moving earlier fights it.

Here’s roughly how long your clock takes to adjust with no help, at those rates:

Once a destination is 10 or more hours ahead, it can be quicker to go the long way round. A clock 10 hours ahead takes about 10.5 days to reach moving earlier, and about 9 days moving 14 hours later. The planner compares both and picks the shorter.

How do you time the light?

The planner hangs everything on your body temperature low, the coldest point of your night. Eastman and Burgess put it about 3 hours before you usually wake. In a 2003 Harvard study, bright light before the low moved the clock later, and light after it moved the clock earlier.

• Flying east, avoid bright light in the 3 hours before your low and get outside in the 3 hours after it.
• Flying west, do the opposite.
• Each day the low moves, about an hour earlier going east or about an hour and a half later going west, so the light window moves with it.

The 3 hour widths are our choice, built on the direction those studies found.

What does a real trip look like?

New York to Paris in winter. Paris is 6 hours ahead. You sleep 11pm to 7am at home, so your low is about 4am New York time, which is 10am in Paris.

• Before you fly, if you can, go to bed and get up an hour earlier each day for the last 3 days, with bright light soon after waking. In the lab, moving sleep an hour a day earlier with morning light and afternoon melatonin shifted the clock about an hour a day without jet lag.
• The day you land, sleep on the plane if you can, since it’s night where you’re going. Wear dark sunglasses until about 10am, then get outside from 10am to 1pm.
• That night and the next 3, take 0.5 to 5 mg at about 10:30pm, starting low, and sleep 11pm to 7am local time.
• Each day after, the dark and light windows move about an hour earlier. You’re about adjusted after 6 days.

Los Angeles to Tokyo in winter. Tokyo is 17 hours ahead, which is the same as 7 hours behind, so your clock moves 7 hours later. Your low is about 4am in Los Angeles, which is 9pm in Tokyo.

• The day you land, stay awake on the plane or keep naps short. Get outside from about 6 to 9pm, then keep the room dark.
• At bedtime, 0.5 to 5 mg at about 10:30pm if you want it, though the trials found less benefit flying west.
• You’re about adjusted after 5 days.

For trips under 5 zones the planner gives you light alone, since the trials found the benefit from 5 zones up. For trips of 3 nights or fewer it tells you to stay on home time as far as you can. No trial has tested short trips, but your clock barely starts moving before you fly home.

What about night shifts?

The evidence is thinner. A 2014 Cochrane review of 15 trials with 718 shift workers included 9 trials of melatonin. On low-quality evidence, melatonin added about 24 minutes of daytime sleep after a night shift and didn’t help people fall asleep faster. A second review of 8 studies came out inconclusive.

The bigger problem is light. You finish at 7am and drive home into the morning sun, which is light after your temperature low, pushing your clock back toward days. Then you try to sleep in a bright bedroom.

Here’s the planner’s plan for 12-hour nights from 7pm to 7am, home at 7:45am in daylight:

1. Very dark sunglasses on the way home, if it’s safe for your drive. Eastman and Burgess recommend very dark sunglasses to keep light off your eyes at the wrong hours.
2. One sleep block at the same hours every work day, here 8:30am to 3:30pm.
3. A blacked-out bedroom, or an eye mask.
4. If you try melatonin, 0.5 to 1 mg once you’re inside, before the day sleep. Never before driving.
5. On days off, when you sleep at night, melatonin has no role.

In a 1997 study, 21 night shift workers took 0.5 mg at bedtime for a week, and their own melatonin came back at the same height afterward. The pill moved the timing and left their own production alone.

If you’re too sleepy to drive home, don’t drive.

I’m only there for 3 days. Do I bother?