"A Good Night’s Sleep Isn’t a Luxury; It’s a Necessity", from the New York Times on May 30, 2011
"Its benefits include improvements in concentration, short-term memory, productivity, mood, sensitivity to pain and immune function." This article is a good reminder, especially when sleep has lost some of its value over time. http://www.nytimes.com/2011/05/31/health/31brody.html?emc=eta1