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Lesson of the Day: Circadian Clocks are HARD to shift!

The views expressed are those of the author and are not necessarily those of Scientific American.


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I originally published this on February 28, 2007.

This is a story about two mindsets – one scientific, one not – both concerned with the same idea but doing something very different with it. Interestingly, both arrived in my e-mail inbox on the same day, but this post had to wait until I got out of bed and started feeling a little bit better.

First, just a little bit of background:

Circadian oscillations are incredibly robust, i.e., resistant to perturbations and random noise from the environment. Ricardo Azevedo has described one model that accounts for such robustness in his two-part post here and here and others have used other methods.

Circadian clock can be re-set only by a very limited set of environmental cues. For each cue, there is a dedicated, evolved pathway by which such cue resets the clock. Light is one such cue – the one we understand the best, down to each molecule. Temperature is another one (in warmblooded animals, the clock is exposed to a constant temperature of the body, but taken out into a dish, it does entrain to temperature cycles). In some animals, olfactory cues (smell) can affect the clock. Scheduled feeding and bouts of exercise can also reset the clock. In each case we have a decent idea which part of the brain is responsible for feeding this information to the clock and by which neurotransmitters or hormones.

For a long time it was thought that humans are especially sensitive to social cues, but perhaps this conclusion is erroneous as, at the time, it was thought that very dim light cannot shift human clocks so many exchanges between subjects and staff occurred in dim light. We now know that dim light resets the human clock.

Clock regulates timing of thousands of body functions, sleep being only one of them. Most of the functions timed by the clock cannot themselves feed back on the clock. Of the hormones whose release is timed by the clock, melatonin is the only hormone that can phase-shift and entrain the rhythms, while in some organisms, sex steroids can also have a slower, long-term effect on the period and phase.

So, can the act of sleeping reset the clock?

This is not a bad question as there is nothing theoretically against such a notion. The question was asked by sleep and clock researchers in the past and, them being scientists, they tested it in several different ways. Every time the answer came out the same: No, timing of sleep cannot affect the working of the clock. Falling asleep and waking up at unusual times does not reset the clock. Naps do not reset the clock.

This is now a well-known fact in chronobiology which was creatively used in the experimental design of the study reported here and here. The question they asked was if the circadian time affects athletic ability in competitive swimmers.

But, how can they eliminate all the other potentially confounding factors, e.g., time since waking-up, time since last meal, etc.? It is impossible to control for all those other factors. So, they did the opposite, they made sure that every confounding factor is present at every time of day and every swimming test. They did it by utilizing the knowledge that naps do not reset the clock. All the swimmers were made to sleep for an hour and be awake for two hours and over and over agaian, for a very long period of time (about 55 hours). They swam 200m during every bout of wakefulness.

What they found was that the time of day made a big difference – as much as 5 seconds (remember that 5 hundredths of the second can make a difference between Olympic Gold and no medal at all!). Afternoon times were better than morning times. Period between 2am and 8am was awful! The 11pm time was the best.

What is also important is that the findings from this study are very similar to findings of previous studies which in no way attempted to control for confounding factors. This suggests that, coaches’ beliefs notwithstanding, all those other factors have little or no effect on swimming performance compared to the effects of the circadian time.

Anyway, that was a good scientific study utilizing the knowledge that repeated naps do not reset the biological clock.

Now, to the second story.

How about a story about a guy who wakes up one morning with a brilliant idea – if something could reset the clock a little bit, perhaps something like a massage, doing a series of those while on an intercontinental flight could potentially beat jet-lag!

Now, someone with a scientific mindset would get on Google and, in two-to-five minutes of searching discover those few cues that actually do reset clocks. No massage there. Back to the drawing board. This idea has no legs. It’s over. One of those many brilliant ideas to discard before breakfast.

But if you do not have a scientific mindset but a predatory business mindset? What then? Then, of course, your next question is not going to be if your idea is valid, but how to turn your idea into dollars. So, you build a website, give it a catchy name of Jet Lag Passport and sell a PDF explaining to the unitiated how to get rid of jet-lag for $19.95. Which doesn’t work.

But, sounding all scientific only brings in some potential customers. How can one bring in some others, for more money? Well, that’s easy. Pepper your idea with additional woo. How about some New-Agey mind-body woo plus some Oriental “medicine”? Sure, why not? People seem to fall for that kind of stuff. You just need to press some acupressure points every two hours and that will help reset your clock (I am wondering how molecular transcription factors in the SCN respond to pressing your nose?!). Oh, and don’t forget to say some magic words as you do this (“Even though I have this jet lag, I deeply and completely accept myself, and I choose to feel good now and when I arrive in (your destination). “) because self-persuasion must really be effective! Oh, drink enough fluids as dehydration prevents this method from working!

Frankly, reading through the PDF (provided to me for free by the author who, for some unexplained reason, thought I’d like it! Sometimes one wonders if the quacks are really aware how bad their stuff is! Or is it the huge ego?). I did not know where to start. Nothing in it makes any sense. This is just NOT the way a human body works. Not even close. Molecules in our cells could not care less what we say and what we want and what parts of the skin we touch. I could not deceive my body that I was feeling fine last week – I had to take antibiotics instead. Likewise, chanting and acupressure and self-suggestion will not in any way change the rate of transcription of clock genes in your SCN or the rate of degradation of the clock proteins. And that is just SCN. Jet-lag is not a symptom of resetting of the SCN clock but the result of internal desynchronization between myriads of clocks in all our organs. Drinking water will not help, sorry.

Remember the beginning of this post? How difficult it is to shift the clock? How robust it is? How useful this fact was for the swimming study? Only people’s gullibility can match its robustness!

But then I looked around the website and realized that this is no naive amateur writing this. This is a subset of the notorious Emotional Freedom Technique (EFT) which is a variant of the Thought Field Therapy (TFT). See the first link for a who’s-who in medical woo on the sidebar (starting with Deepak Chopra of course) and check the second link for a beautiful fisking of another EFT-related quackery by Orac. There is an ocean of woo there – far too much for just one person – little me – to debunk on one’s own. So, let’s just remain on the topic of jet-lag.

If anyone offers to sell you a cure for jet-lag that does not combine, in some way, use of bright lights, melatonin pills and strict scheduling of meals and exercise upon reaching the destination, do not buy it – it will not and cannot work. There are just no physiological explanations even how it might work – it is so New-Agey and gooey and mystical it is not even approaching a form of a testable hypothesis and thus does not warrant any time wasted by scientific researchers on it. Go read something else….The correct information about alleviating jet-lag is available online for FREE!



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Comments 3 Comments

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  1. 1. fc47834 11:16 am 11/1/2011

    There is a lot of information out there on the use of melatonin and bright lights to shift the clock, but less on the use of exercise and timing of meals, which you also mentioned as helpful. Are there any good resources out there for someone looking to learn more about this?

    Link to this
  2. 2. Venomlust 7:43 pm 11/2/2011

    I like reading all of your articles, Bora, but debunking New-Age nonsense is especially fun for me. Cheers!

    Link to this
  3. 3. Laurraine 7:46 pm 11/2/2011

    I’ve never suffered from jet lag. I have lived in many areas of the US and have flown as far away as Australia. As long as I reset my watch, my body just seems to follow the clock.

    Link to this

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