what is the least amount of sleep one should have?

8 hours is for young ones whose below secondary education.but 6-7 hours for adults but there are people sleeping for about 12 hours and Im amazed cause for me I will be getting a headache

I think, like with most things in life, it's entirely down to the individual, as our needs are all different. I need at least 8 huors, but some people can happily and comfortably get by on maybe 4 or 5 hours. I think what your body tells you is a good indicator, in that if you feel tired, then your body needs rest and sleep - so long as you've had a health check and everything is OK, just to make sure that wanting to sleep a lot isn't a sign of something wrong.

since I've had a baby it seems like my chemistry has changed. I need at least 5-6. Under that I cant function!Before my baby I used to at least have 8.

It really depends on the person. I've heard that it's different for everyone. Some people feel energized after four hours of sleep while others feel like they've lost time. For me it's 7 hours. I always feel like crap if I've only slept 7 hours or less.

for me, it's 5-8 hours... i would turn out to be a walking zombie when it's less than 5 hours