Jet lag is the cluster of symptoms that arise after rapid travel across multiple time zones, caused by a temporary mismatch between your internal body clock and local time at the destination. Common symptoms include insomnia or hypersomnia, daytime fatigue, impaired concentration, digestive upset, and low mood.
Why eastward travel is harder: Your body clock naturally drifts later (delays) over time. Eastward travel requires advancing the clock (sleeping and waking earlier) — against its natural direction, making adaptation harder. Westward travel aligns with the clock's natural drift, so recovery is typically faster. A useful rule of thumb: allow roughly 1 day of recovery per time zone crossed.
Strategies for faster recovery:
Pre-travel adjustment: • Eastward travel: Start gradually shifting bedtime and wake time 1 hour earlier per day for 2–3 days before departure • Westward travel: Delay your schedule slightly before leaving
Light exposure management (the most effective tool): • After eastward travel: Get bright light exposure in the morning at your destination to advance your clock • After westward travel: Get evening light exposure to delay your clock • For precision, tools like the Timeshifter app generate personalized light exposure schedules
Melatonin: Low-dose melatonin (0.5–1mg) taken 30 minutes before your desired sleep time at the destination has solid evidence for shortening adaptation time — particularly for eastward travel.
During the flight: • Immediately set your watch to destination time when boarding — mentally switch time zones • Try to sleep and stay awake according to destination time, not your home timezone • Stay well hydrated; avoid alcohol and excess caffeine