Sleep glorious sleep! And clearance of brain metabolites…

I’ll preface this post by saying how much I love sleeping. Not just because we’ve got a new baby and we’re a bit sleep deprived… I have always loved sleeping. Sleeping rocks.

i love sleep

  • Without sufficient sleep, mood and cognition are impaired (no kidding – I have the pleasure of being both a doctor and a new mother. I am a sleep deprivation specialist. ¬†Once, in the early days of bub, I was annoyed that the dirty dishes hadn’t been put into the dishwasher… until I realised I had stacked them into the fridge)… this was swiftly followed by further annoyance that our fridge didn’t come with a dual-dish-washing-function…
  • When animals are kept from sleeping, they ultimately die (it’s sad but true – most of our current medical knowledge comes from studies carried out on animals or during wartime);
  • Being awake uses brain function (in most people anyway, certain members of Government excepted), which produces brain cell metabolites (waste products);
  • An increase in these waste products is a trigger for sleep.

So I was interested to read this journal article about sleep…

It found that:

  • During sleep the interstitial space in the brain (the space around the brain cells) which is bathed by cerebrospinal fluid, was found to expand by 60% during sleep;
  • This results in brain cell waste products being cleared more rapidly (they go into the blood, and then to the liver for detoxification).

The authors suggest that we feel restored in the morning because the brain has freed itself of toxins.


Xie L et al. Sleep drives metabolite clearance from the adult brain. Science 2013 Oct 18; 342:373.
Herculano-Houzel S. Sleep it out. Science 2013 Oct 18; 342:316. (

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One Comment

  1. Sleep, glorious sleep! Don’t care when it happens!
    My 14 wk old was up 4 times between 12:30 and 7:30. Back to newborn days. Hoping it’s temporary!
    Can totally relate to needing sleep.

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