How Your Body Clock Type Shapes Your Jet Lag

Dr Steve Jasper

Owls Versus Fowls: How Your Body Clock Type Shapes Your Jet Lag

Are you someone who bounces out of bed at 5 AM for a jog? You’re a fowl. Do you prefer to wake at the crack of noon? You’re an owl.

Scientists call this your chronotype: whether you’re a morning lark, a night owl, or somewhere in between. It’s your body’s built-in schedule for sleep, alertness and physiology, shaped by genetics and light exposure. It also influences how easily your internal clock can shift when you travel.

Jet lag is your circadian clock out of step with local time after crossing time zones.

Your chronotype sets the direction your clock naturally prefers to move:

  • Morning types tend to have clocks that run slightly shorter than 24 hours and drift earlier. They generally handle eastward travel, which means advancing the clock, better.
  • Evening types tend to have clocks that run slightly longer than 24 hours and drift later. They usually cope better with westward travel, which means delaying the clock.

When you travel in the direction your chronotype already leans, your clock is being asked to do what it wants to do anyway. Jet lag is milder and clears sooner. Travel against it, and your clock resists, so symptoms are stronger and last longer.

Why chronotype explains the exceptions

For most people, eastbound trips are worse because advancing the clock is harder than delaying it. Chronotype explains who breaks the rule:

  • A strong night owl flying east may feel wrecked, because they must fall asleep and wake far earlier than their biology allows.
  • A strong morning lark flying west may struggle more than average, because staying up late and sleeping in conflicts with their early-rising tendency.

In practice, your chronotype helps decide whether you’re in the “east is worse” majority or the “west is worse” minority.

Your chronotype changes with age

Chronotype isn’t fixed for life. People tend to become later through adolescence and early adulthood, then gradually earlier through midlife and older age. Older travellers also tend to have less flexible circadian systems, so even a “good direction” trip can feel tougher and take longer to recover from.

Practical takeaway

If you know your chronotype, you can anticipate your jet lag pattern:

  • Night owl heading east? Expect a harder trip. Start shifting earlier before you go, and time your morning light carefully. On big eastward trips, light at the wrong moment can push your clock the wrong way.
  • Morning lark heading west? Prepare for late nights, and use evening light to help your clock delay.

Your chronotype won’t eliminate jet lag, but it explains why the same trip can feel completely different from one person to the next, and why direction matters more for some travellers than others.

Not sure whether you’re an owl or a fowl? I can help you find out and build a plan around it. Book a session with me on EveryExpert.