Why Jet Lag Happens

Written by Studio AM.

Fly across many time zones, and your body arrives before your inner clock does. This tired, foggy feeling is called jet lag. Inside every person is a kind of clock that tells the body when to sleep and when to wake. It is set mostly by light.

For a long time this clock matched the sky where you lived. Then a fast plane drops you in a place where noon feels like midnight to your body. Your inner clock still runs on the old time and takes several days to catch up. That is why, in a new time zone, you may feel wide awake at three in the morning and sleepy at noon.

Light helps the body clock reset, but its timing matters. Useful timing depends on the direction of travel and how many time zones you cross. A gradual change in local time may give the body more time to adjust than a rapid one.

Questions

Choose an answer. The explanation appears after you answer.

  1. Question 1 of 4

    What is the main idea of the passage?

  2. Question 2 of 4

    According to the text, what mostly sets the body's inner clock?

  3. Question 3 of 4

    Why might a gradual time-zone change be easier to adjust to?

  4. Question 4 of 4

    In this passage, "reset" most nearly means

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