A new study, published in American Association for the Advancement of Science’s magazine Science, revealed yet another benefit of a good night’s rest.  Specifically, the researchers indicate that sleep has a critical function in ensuring metabolic homeostasis.  Using a mouse model, the scientists set up an experiment in which the mice were observed in natural sleep and under anesthesia.  In either case, there was an increase in the flow of cerebrospinal and tissue fluid as well as clearance of beta amyloid.  The increased flow and removal of waste products that are potentially neurotoxic, gives sleep a restorative function.

According to an analysis of the study in BBC News, the brain chooses between an awake and aware state or an asleep and cleaning state.  In the latter, brain cells shrink during sleep to open up the gaps between neurons and allow fluid to wash the brain clean.  If the brain has to use its limited energy on being awake and aware without sufficient time to clean, the toxins could cause damage.  Those toxins have been shown to play a role in the development of brain disorders.

Cells in the brain, specifically the glial cells that keep nerve cells alive, shrink during sleep. This increases the size of the interstitial space, the gaps between brain tissue, allowing more fluid to be pumped in and wash the toxins away.  When the mind is awake, this cleaning function appears to be impossible.  This indicates that, with current scientific and medical technology, sleep is necessary to complete this essential function.

For individuals that have sleep troubles, artificially induced sleep can also accomplish these functions.  Science Daily reports findings from a study in which anesthesia drugs turn sleep circuits and functions in the brain on.  This indicates that, artificially induced sleep is good enough for ensuring that a person gets a sufficient amount of sleep to cleanse the brain of neurotoxins.

In particular, beta amyloid is important to remove from the brain.  According to the Alzheimer’s Association, plaques in the brain form when protein pieces called beta amyloid clump together. Beta amyloid comes from a larger protein found in the fatty membrane surrounding nerve cells.  Beta amyloid has a sticky texture and will gradually build up into a plaque.  The most damaging form of beta-amyloid may be groups of a few pieces rather than the plaques themselves. The small clumps may block cell-to-cell signaling at synapses. They may also activate immune system cells that trigger inflammation and devour disabled cells.