Neuroscientist Russell Foster describes sleep as “the single most important behavioral experience that we have.” He describes how our perception of sleep has changed over the course of human history — from that of an appreciated necessity in the 16th century to “a criminal waste of time” by the start of the 20th century. Dr. Foster describes the importance of sleep in memory consolidation and problem solving, and highlights the link between sleep deprivation and setbacks such as poor judgement, drug/alcohol consumption, weight gain, mental illness and even cancer.