Eastward vs. Westward: Why Direction Matters
Your body finds it easier to stay awake later (delay the clock) than to sleep earlier (advance it). This means westward travel is biologically easier than eastward travel. Flying west from London to New York: you are just staying awake slightly later. Flying east from London to Tokyo: you need to advance your clock by 9 hours — approximately 5 days of recovery at the biological maximum rate.
The human circadian clock advances at maximum 1 hour per day (eastward) and delays at maximum 1.5 hours per day (westward). A 5-hour time zone crossing requires approximately 5 days of recovery eastward, or 3 days westward.
The Light Protocol
Light is your most powerful tool. The timing of light exposure determines which direction your clock shifts. Seek light during the hours that correspond to morning at your destination. Avoid light during hours that correspond to night at your destination. This means: on a London-to-New York flight arriving at 2 PM local time (7 PM London time), get outdoor afternoon light immediately — do not sleep until at least 10 PM local time.
Melatonin Timing for Jet Lag
Melatonin taken at the right time can accelerate clock shifting by 1–2 days. For eastward travel: take 0.5mg melatonin at 10 PM destination time for 3–4 nights after arrival. For westward travel: take 0.5mg melatonin at 11 PM–midnight destination time for 2–3 nights. Low dose (0.5mg) is more effective for circadian shifting than the high-dose products commonly sold.
Pre-Travel Adaptation
For important trips (business, events), begin shifting your sleep 2–3 days before departure. For eastward travel: go to bed 30 minutes earlier each of the 3 days before. Get morning light slightly earlier. This "pre-loads" the adaptation and reduces recovery time at destination by 1–2 days.
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