Saturday, 18 February 2012

Food - can it shift the Circadian Rythm?

In this video from MSN there is a small part about how food timing can change the circadian rythm.

The part in questions features Patrick Fuller from Harvard, and the pubmed paper in question is this one.

I dont access to the full paper but the abstract gives us the clue as to what its all about,
"When food is plentiful, circadian rhythms of animals are powerfully entrained by the light-dark cycle. However, if animals have access to food only during their normal sleep cycle, they will shift most of their circadian rhythms to match the food availability."

Well anyway, does it work?

It does make sense in theory, if your a predator and theres only certain times of day you would be able to catch your prey, it would work against you if your body clock was such that it was telling you to sleep during those hours.

From what I could gather, first you need to be in starvation mode, which is you need to have fasted for atleast 16 hours first.

Then, during the time you would normally be asleep, have a meal.

I will have to experiment to see if this actually works at all, and to figure out the exact timing, the timing to shift our body clocks forward.


  1. Bah it would not let me watch it :( Says I can't from my current location?

    Actually ghrelin (which ties into onset of meal time) is believed to directly modulate the circadian rhythm.

    Ghrelin also affects mood and motivation (dopamine).

    Ghrelin is very significantly controlled by insulin levels, and a hallmark of obesity is Ghrelin is always low, even after an overnight fast, as abnormal hyperinsulinemia keeps the endocrine system constantly locked in a fed state (so ghrelin does not decline normally).

    There was a time I was considering a link between suppressed chronically low ghrelin and some of the depressive symptoms I experience eating a "normal" insulinogenic diet. I think ghrelin is involved because I experienced low grade dysphoria early on in leptin therapy, and leptin also powerfully suppresses ghrelin. I also seem to have circadian rhythm component due to amelioration of symptoms with light therapy.

    I have sort of abandoned doing more research into this but my intuition is that ghrelin is quite important in mood and motivation, and when it is too low (e.g. obesity and hyperinsulinemia) the person may be given to apathy and dysphoria .

  2. Dunno why you cant see it Wooo, might be country restricted, theres alot of videos I cant watch just because im in UK and there are copyright issues.

    I did come across alot of Ghrelin stuff in my earlier blogging days, Ghrelin helps with slow-wave sleep, the guy on posted a study showing a strong link with ghrelin and circadian rhythm.

    The most interesting find though was a study measuring ghrelin over 24hours in both lean and obese people.

    In lean people, there was a massive spike in ghrelin during bedtime and sleeping hours, which did not occur with the obese people, one has to wonder what horrible side affects that has for fatties -.-

    This is the study