Friday, October 18, 2013

Why sleep?

For brain cleaning. 

Study finds that spinal fluid pumps around the brain of sleeping mice, flushing out waste products.

The study is here:

Vol. 342 no. 6156 pp. 373-377
DOI: 10.1126/science.1241224                        

Sleep Drives Metabolite Clearance from the Adult Brain


  • "The conservation of sleep across all animal species suggests that sleep serves a vital function. We here report that sleep has a critical function in ensuring metabolic homeostasis. Using real-time assessments of tetramethylammonium diffusion and two-photon imaging in live mice, we show that natural sleep or anesthesia are associated with a 60% increase in the interstitial space, resulting in a striking increase in convective exchange of cerebrospinal fluid with interstitial fluid. In turn, convective fluxes of interstitial fluid increased the rate of β-amyloid clearance during sleep. Thus, the restorative function of sleep may be a consequence of the enhanced removal of potentially neurotoxic waste products that accumulate in the awake central nervous system. "

    Are there other states of being where this occurs - in humans ?

    Does zazen, upright sitting, also have a function like this?

    What of the cleansing of body-mind practice like tonglen in Vajrayana Buddhism or Hakuin's naikan?