How many hours of sleep do you need to function?

I also need at least 6 hours of sleep each night or I'm useless the next day. I would love to sleep eight hours but that hardly ever happens. I can't even sleep the 6 hours straight without interruption from my dog or a noise waking me up. After turning fifty my sleep patterns have changed drastically. How I long for a night of complete sleep without waking after 3 or 4 hours of sleep. On top of all this if I sleep more then 6 hours my lower back hurts when I wake up. So I feel I can't win either way.

This is a good discussion since I know some people need more sleep than others,and I think how much sleep I need varies and right now I am working third shift so I work set hours and some days I will sleep more than others,some days I will twelve hours and somedays I will eight hours,and sometimes the more I sleep the more tired I am and I end up waking up with a headache,and sometimes the less sleep I get the more refreshed and ready to go I am when I wake up.

For me, six hours is enough to me not to get sleepy in work or in school. But I notice that I lack focus and I am less alert if I only sleep six hours or less. Usually my average sleep time is 8 to 9 hours specially if it is vacation and I am well alert and have more focus if i sleep longer hours. Also it depend if I sleep deeply or I have I good night sleep like if I sleep in shorter hours but my sleep is deeply I feel like I sleep long and can function well.

At least 7 or 8 for me, preferably more.

I need at least 8 hours for sleeping every day , or I will get tired easily in working . And I always take a nap at noon . That can refresh me and regain energy .

I need 7-8 hours at night... if i sleep more i wake up very tired...

i think i can have 6 to 8 hours or more if possible,hehe i don't have much energy if i slept less than that and i always find myself weak if i woke up in the middle of my sleep.my head really aches,but i have nothing to do,specially when it's urgent i have to get up having head ache.if possible,i do find time to sleep if i can!

I usually sleep in the night for 6hours. but when i m doing tiresome work i sleep 2 hours extra in the afternoon.. If you dont give your body the rest it needs it will compensate it i weekends... Otherwise performance of a person decrease