Daily Protocols

Sleep · Protocol 15 of 15

Beat jet lag with well-timed light

2 days before you fly, plus 2 to 3 days afterAdvancedGood evidence

1In 30 seconds

Before you fly, nudge your wake time, light, caffeine and exercise 30 to 45 minutes towards the new time zone. After you land, time your light exposure using your home body clock for the first 2 to 3 days, and eat on local time.

2Picture it

Flying east: Wake 30-45 minutes earlier, Bright light on waking, Caffeine early, Exercise soon after waking. Flying west: Wake 30-45 minutes later, Bright light after sunset, Caffeine a little later, Exercise a little later.Flying eastFlying west •Wake 30-45 minutes earlier •Bright light on waking •Caffeine early •Exercise soon after waking •Wake 30-45 minutes later •Bright light after sunset •Caffeine a little later •Exercise a little later

3Why do it

  • 1

    You adjust to the new time zone faster, so you are sharper at meetings and enjoy holidays sooner.

  • 2

    You avoid the classic trap of sleeping well on night one and then lying awake on night two.

  • 3

    The tools are mostly free: light, darkness, meal timing and exercise.

4How to do it

  1. Flying east: starting 2 days before you leave, wake 30 to 45 minutes earlier than usual, get bright light straight away, have caffeine early and exercise within 60 minutes of waking.
  2. Flying west: shift your wake time, caffeine and workout 30 to 45 minutes later, still with no caffeine 8 to 10 hours before bed, and look at bright artificial light for 1 to 2 hours after sunset.
  3. Work out your home temperature minimum, about 2 hours before your usual wake time. If you wake at 7 a.m., it is roughly 4:30 to 5:30 a.m. home time.
  4. For the first 2 to 3 days after landing, use home time. Bright light in the 1 to 2 hours after your temperature minimum shifts you earlier, which suits eastward trips. Light in the 1 to 2 hours before it shifts you later, which suits westward trips. After flying east, wear dark sunglasses for the 2 to 3 hours leading up to your home temperature minimum on your first 2 days.
  5. Eat meals at local times. Some people fast for 14 to 16 hours before the local breakfast so they arrive hungry. Keep exercising early in the local day, and use a 5,000 to 10,000 lux light box if it is dark or very cloudy.
  6. For trips of under 2 days, stay close to your home sleep, meal and exercise times instead.

5Make it work in India

  • Flights from India to the USA, the UK, Europe or the Gulf take you to earlier clocks, so treat them as westward trips that need later nights. Trips to Singapore, Japan or Australia move you to later clocks, so treat them as eastward trips.
  • On overnight red-eye flights, sleep on the plane according to your destination’s night, wear an eye mask, and skip the in-flight drinks.
  • India uses one time zone, but the sun rises over an hour earlier in the northeast than in Gujarat. If you move between them for work, use morning daylight to reset over a few days.
6The long read: the science2 min read · tap to open

Your body clock takes its cues from five main signals. In order of strength, they are light, temperature, meal times, exercise and social contact. When you land in a new time zone, your clock is still set to where you spent the last week or so. You cannot just switch it overnight.

The key idea is your temperature minimum, the lowest point of your body temperature. It falls about 2 hours before your usual wake-up time. Light acts on your clock differently on each side of this point. Bright light in the 1 to 2 hours after it moves your clock earlier, so you want to sleep and wake earlier. Bright light in the 1 to 2 hours before it moves your clock later.

Here is the trap. Imagine flying from San Francisco to London, 8 hours ahead. You land in the morning and soak up the sunshine. But your body still thinks it is around midnight in California. To your clock, that morning sun is a blast of light at the worst possible time. It pushes you later, which is the wrong way. Many people sleep fine on the first night, from sheer tiredness, then lie awake on the second.

That is why you plan light by your home clock for the first 2 to 3 days. After that, follow the normal morning and evening sunlight protocols on local time. Daylight, even through clouds, is nearly always brighter than indoor light, so get outside at the right times.

Most people find flying east harder, because staying up late is easier than falling asleep early.

Good evidence Using timed light to shift the body clock is well studied in laboratories, but real-world jet lag trials are fewer, and the temperature-minimum method is hard to apply exactly.

Questions people ask

Is it worth adjusting for a very short trip?

For trips of under 2 days, it is often better to stay close to your home schedule for sleep, meals and exercise. You will have less to undo when you return.

Do I really need a light box?

Not always. Outdoor daylight at the right time works best, even on cloudy days. A portable 5,000 to 10,000 lux light box helps when you land in darkness or the weather is very gloomy.

7Be careful

Never look straight at the sun or a light box at close range for long. Do not wear dark or blue-blocking glasses while driving. If you take medicines at set times, such as insulin or contraceptive pills, ask your doctor how to adjust them for the new time zone.

8Try it for 7 days

Tap a day each time you followed my jet lag plan.

From the book: “A Tip Sheet for Avoiding Jet Lag” (Sleep Protocol 15). Evidence rating and India notes are our own.

Inat Therapy · Anahita Tanwar, Clinical Psychologist · online sessions across India

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