Doctors may tell you to sleep 7-8 hours but I think that depends on an individual. Some may sleep for long others do not sleep at all. I sleep for as long as for a few days but most of the time I sleep a maximum of three hours or sometimes I don't sleep at all.
Sometimes it depends on how you have trained your body, supposedly a normal sleep for an adult should be between seven to eight hours. If you consistently sleep for lesser hours your body may get used to it, my fear that may not be healthy.
When I was younger, 8,9 even 10 hours of sleep. But now, I can sleep 6h for days and in some point if I feel super tired I sleep for 9h and I'm fine again.
In a chat I asked a 50 years old man how many hours he spent sleeping he told me six hours and sometimes seven. I was thinking if those hours were good enough for adequate sleep
If I won't be doing anything the next day, I would literally sleep all day and wake up around 9 in the evening for dinner. I do not have a lot of time to sleep most of the times so if I would be given such chances I grab them immediately. I just sleep 2 to 3 hours a day that's why I sleep for hours whenever I won't be doing some work.
The same formula I adopt, trying to compensate for my lost hours of sleep during the week I'd sleep for extra hours at least nine on weekends. I find out that other days excluding weekends, I am putting in about four hours for sleep.
I go to sleep around 11:30 on school days since I need to get up around 6:50, so on weekdays I get about 7-8 hours of sleep. Sometimes I'll sleep either earlier/later than usual, so I get more/less sleep but it normally stays in the 7-9 hour range. On Saturdays and Fridays I tend to sleep longer so get about 10-11 hours which I really don't need but a little more sleep doesn't hurt anyone!
Many nights these days I go to bed late and some times I'd have to wake early around 7:30 in the morning to catch up my offline job starting around 9:00. Such days my sleeping hours is around four to five hours. I try to compensate for the loss hours by 'over sleeping' on weekends
For me I usually require at least 5 hours of sleep at least. However, the last few days I seem to be dozing off a bit more than that. For me 5 hours seems like a good time frame to recharge.