Which statement about jet lag is correct?

• A. It results from a mismatch between internal clocks and local time, and adaptation improves with light exposure
• B. It is caused solely by alcohol consumption during travel
• C. It resolves within 24 hours regardless of actions
• D. It only affects ground personnel

Answer: (A)

Jet lag happens when your internal body clock gets out of sync with the new local time after crossing time zones. The brain’s master clock relies on light cues to reset, so exposure to bright light at the right times helps shift that clock toward the destination’s schedule. For eastward travel, morning light helps advance the clock; for westward travel, evening light helps delay it. Alcohol isn’t the cause of jet lag, and it can worsen sleep quality but doesn’t explain the core phenomenon. Jet lag doesn’t always resolve within 24 hours—adjustment can take several days depending on distance and individual factors. And it’s not limited to ground personnel; anyone traveling across time zones can experience it.