I am interested in knowing how our Circadian Clock responds (and if there are resultant changes) when we travel across Time Zones?

UPDATE 24th April

I am reopening this question as the statement in the answer "When you travel to different time zones, your circadian clock will be off" has further confused me. If it's the case, then I am looking to get a better explanation than that (with solid references). Thanks

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    $\begingroup$ Welcome to Biology S.E.! From what I understand, the actual time zone shouldn't cause too much of an issue. However, flying from light into darkness or the other way around seems it could confuse your internal clock. And if you crossed several time zones and then tried to sleep at your normal time and it was still light out... That could be confusing as well. $\endgroup$
    – L.B.
    Apr 3, 2015 at 16:23
  • $\begingroup$ Just removed some irrelevant tags. $\endgroup$
    – David
    Aug 25, 2017 at 12:53

1 Answer 1


When you travel to different time zones, your circadian clock will be off (incorrect). The reason your circadian clock will be off is because your body has adapted to the time zone you are from. When you enter a new time zone, your circadian clock will still be functioning on the old the time zone. If the time zone difference is $\pm 12$ hours, this is a huge adjustment.

However, your body takes inputs from the environment. That is, you may see it is day light when your body is under the impression it is evening. Your circadian clock is controlled by your master clock located in the hypothalamus. As you take in these external inputs that counter your circadian clock, a group of nerve cells called the suprachiasmagic nucleus will slowly make the master clock adjustment [1]. This resetting can take a few days.

Additionally, there has been a bit of research on exercise reducing jet lag. In a study, researchers test outdoor exercise with flight crew members and found that the group that exercised outdoors had a hastened re synchronization of their circadian clock [2].

Another interesting article is Jet Lag in Athletes.

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    $\begingroup$ Thank you! May I have reference for "When you travel to different time zones, your circadian clock will be off." $\endgroup$ Apr 3, 2015 at 16:34
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    $\begingroup$ @dustin - that sentence confused me too; as it stands, it reads like "when you travel to different time zones your circadian clock will be [switched] off". I had a raised eye brow and had to re-read it too. $\endgroup$
    – AliceD
    Apr 16, 2015 at 23:47
  • $\begingroup$ @AliceD you can edit if you want. It makes sense to me, so I don't see the issue. $\endgroup$
    – dustin
    Apr 17, 2015 at 1:32
  • $\begingroup$ @dustin - up to you, it may just be a language barrier making me to mis-read your sentence. It's not critique, just an attempt at analyzing POs question on the reference :) $\endgroup$
    – AliceD
    Apr 17, 2015 at 1:39

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