Light Therapy for Jet Lag: Using Light to Reset Your Body Clock

Overview

Light exposure is the single most powerful tool for adjusting your circadian clock after crossing time zones. Understanding when to seek light and when to avoid it is the key to accelerating jet lag recovery. The principle is straightforward: light exposure in the morning advances your clock making you sleepy earlier, while light exposure in the evening delays your clock making you sleepy later. After eastward travel you need to advance your clock so you should seek bright morning light at your destination. After westward travel you need to delay your clock so evening light exposure is beneficial. The critical detail that many people miss is that there is a forbidden zone for light exposure: bright light at the wrong time can actually shift your clock in the wrong direction making jet lag worse.

Practical Light Exposure Protocols

For small time zone changes of 1-3 hours simply spending time outdoors at the destination is usually sufficient. For larger changes of 6 or more hours a more structured approach is needed. Calculate your core body temperature minimum time, then seek bright light for 30-60 minutes starting 1-2 hours after that point to advance your clock, or 1-2 hours before to delay it. Shift this light exposure window by 1-2 hours each day as your clock adjusts.

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