Why jet lag feels like the flu

When you fly across several time zones, the clock in your brain starts to shift with the new daylight. The clocks in your gut, liver and muscles shift on their own schedules.

For a few days, your organs are living in different time zones. That internal mismatch, not only the lost sleep, is part of why you feel unwell.

Seek daylight in the new morning and eat on local time. You are giving every clock the same message.