A Neuroscientist's Guide to Jet Lag

Why Flying East Is Harder (And What to Do About It)

Photo by Eva Darron on Unsplash

Your body runs on 37 trillion clocks. Every cell tracks time independently, but they all sync to your brain's master clock - a cluster of 20,000 neurons behind your eyes.

When you fly across time zones, these clocks fall out of sync. Your liver thinks it's breakfast; your brain says midnight. The result: jet lag.

While countless articles tackle jet lag (Nat Geo, Healthline, Sleep Foundation, UK Government, Australian Government), most ignore the direction you're travelling. This is despite the fact that eastward and westward travel require completely opposite strategies.

Since flying east forces you to wake earlier - fighting your body's natural tendency to drift later - it's the harder adjustment. We'll tackle eastward travel here, saving westward for Part 2.

Here's the practical approach:

1. Before You Fly: Start shifting 2-3 days early - one hour per day

   • Morning Routine: Light exposure, early breakfast, exercise timing

   • Evening Routine: Screen cutoff, melatonin protocol, dinner strategy

2. During Your Flight: Live on destination time immediately

   • Sleep hygiene essentials and temperature management

   • How to handle meal service disruptions

3. After Landing: Protect your progress

   • First-day light exposure strategy

   • How to nap

   • What to do if you cross more than 5+ timezones

Start Shifting Before You Fly

Most people wait until they land to deal with jet lag. That's too late. The smart approach starts days before takeoff - gradually shifting your entire schedule earlier, one hour at a time.

Sleep, meals, exercise - all move together. Three days gives you a three-hour head start; even two helps. By the time you board, you're already halfway to Paris time.

Why is this better? Your body can only shift about one hour per day comfortably. So if you're crossing six time zones and start adjusting on arrival, you're looking at nearly a week of jet lag. Try to double this pace and you'll just exhaust yourself without additional benefit.

The morning and evening routines below will help you guide this shift naturally.

Morning Routine: Setting Your Body's Clocks

Light (30-60 minutes after waking)
Your master clock needs light to set the day's countdown. Get light early, and sleep comes early. But timing matters: light 2-3 hours before normal wake time backfires because your brain mistakes sunrise for yesterday's sunset.

Eat Breakfast Early
Your liver can't see the sun. It knows morning arrived when food hits. Skip breakfast? Your organs stay on yesterday's schedule while your brain moves ahead. This desynchronisation is exactly what causes jet lag - different body parts running on different times.

Exercise (before 4pm)
Your body uses temperature as a time signal. Morning exercise works best - it amplifies your natural temperature rise, signalling "wake up" to every cell. Afternoon exercise (1-4pm) is neutral; your temperature is already peaked, so extra heat doesn't confuse anything. But after 4pm, avoid it. Your temperature should be falling for sleep, and exercise reverses this drop. Your brain reads sustained heat as "still daytime."

Caffeine (none after noon)
Six hours after that coffee, half the caffeine is still in your system. You might feel exhausted, but your brain can't initiate sleep. Stopping coffee at noon works for most people - but you might need to adjust earlier if you're sensitive.