That’s how long the average person spends sleeping across their 70 years of life (averaged worldwide). Wolfram|Alpha result: here.
That’s enough time to become an expert in 18 skills, if you spend 10,000 hours on each, and still have enough time to take two semesters in a college course. You could get a Ph.D. twice over with that much time, and have enough time left over to read 7,000 books, if you could find that many worth reading. Or perhaps to summarize: there’s enough time to play every video game ever made, get a Ph.D. in CS or Game Design, and then write your own game, and still have time left over.
Which is why sleep research started in 1913 – approximately the year when it became hypothetically possible to sit at someone’s bedside taking notes, I’m sure – and the first all-night EEG that discovered REM sleep was delayed 41 years after the first EEG.
Humanity, your rationality continues to amaze.
(Aside from Wolfram|Alpha, sourced from http://www.stanford.edu/~dement/history.html and Wikipedia.)