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The Biology Of The Food Coma



sharma-obesity-sleep-deprivationFeeling ready for a nap after a meal is part of normal human physiology – but how exactly does this happen?

Now, Christophe Varin and colleagues from the Centre National de la Recherche Scientifique, Paris, France, in a paper published in the Journal of Neuroscience describe how glucose regulates key neurones in the brain to induce sleepiness.

Their studies in mice focussed on sleep-active neurons located in the ventrolateral preoptic nucleus (VLPO), critical in the induction and maintenance of slow-wave sleep (SWS).

Using both in vivo and ex vivo patch clamp studies, the researchers show that a rise in extracellular glucose concentration in the VLPO can promote sleep by increasing the activity of sleep-promoting VLPO neurons.

As the researchers note,

“The extracellular glucose concentration monitors the gating of KATP channels of sleep-promoting neurons, highlighting that these neurons can adapt their excitability according to the extracellular energy status… Glucose-induced excitation of sleep-promoting VLPO neurons should therefore be involved in the drowsiness that one feels after a high-sugar meal. This novel mechanism regulating the activity of VLPO neurons reinforces the fundamental and intimate link between sleep and metabolism.”

Apart from helping unravel the biology of a phenomenon that every parent of a young child is well aware of, this research raises a number of interesting clinical questions.

Does overconsumption of high-sugar foods necessitate counteracting these effects with caffeine? Is this why sugar-sweetened pop generally contains caffeine (to not put you to sleep)?

Does this also explain the practice of eating a bedtime snack to fight insomnia?

And what does this mean for people with poorly controlled diabetes: do they need to drink more coffee than people without diabetes to get through their day? (not something I’ve heard of).

Interesting stuff…

@DrSharma
Berlin, Germany

1 Comment

  1. Thanks for this post.
    My experience as an occasionally poorly controlled diabetic with an HNF4A mutation affecting the KATP channels is that sleep and overconsumption of carbohydrates are definitely related in some unknown way – if I eat too much particularly at lunchtime I become really uncomfortable with excessive yawning and muscle contortions and the only thing that resolves it (apart from not eating too many carbs in the first place) is to sleep for a short while. It is not like an ordinary sleepiness, it is overwhelming and uncomfortable and one definitely feels that metabolically things are “not right” when it occurs. Sleep gets rid of the symptoms completely within about 25 minutes. Food for thought!

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