The 8 Hour mythGiven the ubiquity of this ‘fact’ it may come as a bit of a surprise to learn that 8 hours is not the recommended length of sleep, and actually never has been. It is disingenuous to suggest that eight hours sleep anything other than an average, it is not an ideal. In the past various writers commented on the number of hours sleep needed, for instance Bullein in 1576 states that “sixe or eight houres will suffice nature”. Vaughan in his Naturall and artificial directions for health 1600 writes “How many houres may a man sleepe? Seaven houres sleepe is sufficient for sanguine & cholerick men; and nine houres for fleagmaticke, and melancholick men”. These historical statements are no different than the current recommendations, the American Academy of Sleep Medicine recommendation for sleep duration in adults is simply over 7 hours. The National Sleep Foundation consensus statement is often quoted 7 to 9 hours; however, the recommendations define times as either as “recommended; may be appropriate for some individuals; or not recommended”. There is no clear explanation of “some individuals”, so it is perhaps clearer to quote the durations of sleep that are ‘not recommended’ which for adults (26-64 years) is less than 6 hours sleep or more than 10 hours sleep.