Well, there was the &quot;washes the brain&quot; mouse study[1] a couple of years ago, which is at least suggestive.<p>1: <a href="http:&#x2F;&#x2F;www.nih.gov&#x2F;news-events&#x2F;nih-research-matters&#x2F;how-sleep-clears-brain" rel="nofollow">http:&#x2F;&#x2F;www.nih.gov&#x2F;news-events&#x2F;nih-research-matters&#x2F;how-slee...</a>