Jet lag is your body's protest against time zones. You've physically moved your body across the planet faster than your circadian rhythm can follow — and the mismatch between your internal clock and local time is what makes you feel exhausted at noon and wide awake at 3 AM. The good news: the science of jet lag is well understood, and there are proven strategies to minimize it.
Why does jet lag happen?
Your body runs on a circadian rhythm — a roughly 24-hour internal clock regulated by light exposure, body temperature, and hormones like melatonin. This clock controls when you feel sleepy, when you're hungry, when your digestion works, and dozens of other biological processes.
When you fly across multiple time zones, your circadian rhythm stays locked to your departure time zone while local time has shifted dramatically. Your body wants to sleep at what it thinks is midnight — even if local clocks say it's noon. The more time zones you cross, the worse the disruption.
East vs west — which direction is harder?
Flying east is consistently harder than flying west — and there's a biological reason. Your circadian rhythm naturally runs slightly longer than 24 hours (closer to 24.5 hours). This means it's easier to delay your clock (go to sleep later, as in westward travel) than to advance it (go to sleep earlier, as in eastward travel).
Traveling from New York to London (eastward, gaining 5 hours) is harder than traveling from London to New York (westward, losing 5 hours). Frequent eastward travelers — like flight attendants on transatlantic routes — report chronic jet lag that never fully resolves.
Before your flight: prepare your clock
The most effective jet lag strategy starts before you board:
- Shift your sleep schedule 2-3 days before departure. Flying east? Go to bed 1 hour earlier each night. Flying west? Stay up 1 hour later.
- Get bright light exposure at the right time. For eastward travel, get morning light to advance your clock. For westward travel, get evening light to delay it.
- Set your watch to your destination time zone the moment you board. Start mentally living in the new time zone immediately.
After arrival: reset fast
Once you arrive, the fastest recovery strategies are:
- Get outside in natural light immediately. Sunlight is the most powerful signal for resetting your circadian clock. Even 20 minutes outdoors in the morning makes a significant difference.
- Stay awake until local bedtime. Napping delays recovery. If you absolutely must nap, limit it to 20 minutes before 3 PM local time.
- Take 0.5mg melatonin at local bedtime for the first 2-3 nights. Low-dose melatonin (not the 10mg doses commonly sold) is clinically proven to accelerate circadian adjustment.
- Eat on local meal times immediately. Your digestive system's clock responds strongly to meal timing — eating breakfast at local breakfast time sends a powerful reset signal.
For calculating exactly how many time zones you've crossed, use our Meeting Planner to see the time difference between your departure and arrival cities.