Beating the Clock: The Science of Jet Lag

Anyone who has crossed multiple time zones knows the feeling: fatigue, insomnia, irritability, and a general sense of being "off." This is jet lag, or desynchronosis, and it's a temporary disorder caused by a mismatch between your new local time and your body's internal clock.

Your Body's Master Clock

Deep inside your brain is the suprachiasmatic nucleus (SCN), a tiny cluster of cells that acts as your body's master clock. When you rapidly travel to a new time zone, your SCN is still operating on your old schedule. The light-dark cycle of your new environment is out of sync.

Why Is Traveling East Harder?

Traveling west lengthens your day, which is easier for your body to adapt to—it's like staying up a bit later. Traveling east, however, shortens your day, forcing you to sleep when your body thinks it should be awake. This is a much harder adjustment for the brain.