What is Jet Lag?

Jet lag is a temporary sleep disorder that happens when you cross multiple time zones faster than your body can adjust. Your internal clock (circadian rhythm) stays synced to your home timezone, causing fatigue, insomnia, concentration problems, and digestive issues.

The Science: Your body uses light exposure to regulate your internal clock. When you fly to a new timezone, light hits your eyes at “wrong” times, confusing your body about when to sleep and wake.

Why Direction Matters

Flying East (Harder): You “lose” time. Your body finds it harder to fall asleep earlier than usual. Recovery: ~1 day per timezone crossed.

Flying West (Easier): You “gain” time. Your body finds it easier to stay up later. Recovery: ~0.5-0.75 days per timezone crossed.

Example: New York → London (5 timezones east) = 5-6 days recovery. London → New York = 3-4 days recovery.

The Role of Light

Light is the PRIMARY tool for resetting your internal clock. Getting bright light at the right time advances or delays your circadian rhythm:

• Morning light: Advances your clock (helps when traveling east)
• Evening light: Delays your clock (helps when traveling west)
• Wrong timing: Can make jet lag WORSE by shifting your clock the wrong direction

This is why simply “adjusting to local time immediately” doesn’t always work — you need strategic light exposure.