I've done more than my fair share of 24 and 36 hours shifts over the years ( when i had young kids and a mortgage , and was always switched on by earning a quid), and after my wife passed away , I started working as a doorman again , so between , the kids , training , and two jobs , most of my days were around 20 hours , and I did that for just under 4 years.
The longest stint I've had with no real sleep , was the two weeks leading up to my wifes passing . She spent her last two weeks on the sofa , with friends and family here around the clock . I spent two weeks sitting on a kitchen chai