Modern sleep science long ago confirmed the importance of sleep in promoting normal human functioning. However sleep’s precise function has remained as elusive as the Holy Grail.
Research published in the newest issue of Science, out today, may give us some clues as to the exact role sleep plays in ensuring our wellbeing. Led by US researchers, experiments on mice have shown their brain is “washed out” twice as effectively during sleep as when they are awake.
In a natural sleep state the spaces between brain cells were found to be more than double in size compared to an awake state, allowing for increased flow of tissue and cerebrospinal fluid. This fluid then sweeps out neurotoxic waste – a group of peptides (β-amyloid) in particular – at a higher rate. In other words, one function of sleep may be to give our brain a thorough, deep clean.
This discovery may have significant implications in the treatment of neurological conditions. These peptides (β-amyloid) make up the plaques found in the brains of Alzheimer’s Disease patients, and as such these findings present a new potential front of research into ways of treating and preventing that debilitating condition.
However some experts have questioned these findings, disagreeing with the conclusion that cleaning is the main role of sleep, and disputing that the human brain will be found to act in the same way as it has been shown to act in mice.
Xie, L., et al. (2013). Sleep drives metabolite clearance from the adult brain. Science, (342) 6156, 373-377.