When I was in my 20s, I worked as much as I could...50-60-70 hour weeks were the norm. (I wouldn't even consider a job that was less than 5x10) That went on until I was in my mid-30s when I was working an 5x8 hour job for the local electrical utility. (with rare overtime) .I slept 7-8 hours per day. By the time I was 45, I was back to working 5x10, 6x10, even 7x12 hour jobs...I rarely got more than 4-6 hours of sleep...Nowadays, (I'm on the + side of 70) I still rarely sleep more than 5-6 hours...with an occasional 30-60 minute nap after breakfast.