If we have &quot;always&quot; been getting &quot;not enough&quot; sleep, then for sufficiently large definitions of &quot;always&quot; I begin to question the &quot;not enough&quot;.<p>The twentieth century saw a lot of poorly-informed scientists second-guessing human body mechanims that have been keeping us alive for millions upon millions of years, on the basis of &quot;studies&quot; that constituted tiny, tiny, tiny, <i>tiny</i> samplings of a horrifically n-dimensional parameter space. I don&#x27;t think the twentieth century scientists came out of it looking too good even now in 2015 and I expect them to continue to look worse as we learn more. This seems as likely a place as any for them to end up having been wrong.