How long can you stay awake?

&gt; Randy Gardner was &quot;awake&quot; but basically cognitively dysfunctional at the end of his ordeal.<p>Reading this bit about a 17 yo HS student at a 1965 science fair was something else! Wow.<p>I tried some different experiments of my own during times when sleep was difficult, and one thing I discovered was that sleep-related subjective experimenting is one of the best uses of that time. Well, for me it was anyway...

&quot;Sleep&quot; has a loose definition and going by the least restrictive one, I cannot go without sleep for more than 18 hours. My brain just stops working.<p>I&#x27;ve been &quot;awake&quot; for 42 hours before, but the the second day was probably the least productive one out of my entire life, and I don&#x27;t even remember it at all, it&#x27;s like it never happened.