I remember a study that showed that people who get less or more than 7h of sleep die sooner (the larger the deviation, the sooner they die). However, I don't think this study normalized against factors that are correlated with excessive/deprived sleep.  

I currently sleep 12h a day and I'm okay with it because I value my sleep time more than daily time [unlike this person][1]. If I sleep less than 12h, I notice that I'm tired during the day. Some people say that they feel lazy and cognitively impaired if they sleep 12h, but this is not the case with me.

I have seen both the 7h recommendation as well as the "sleep as much as you need to" recommendation. Which one is the best one in my situation?  [This question has previously been asked][2] when the original poster asked if his 5h are enough. The top rated answerer was skeptical, and quoted the NIH: "Some people appear to need only about 7 hours to avoid problem sleepiness, whereas others need 9 **or more** hours of sleep". My main question is with respect to the "or more" in the NIH quote: **Is 12h of sleep still reasonable/healthy**?


  [1]: http://fitness.stackexchange.com/questions/1489/how-to-get-rid-of-oversleeping
  [2]: http://fitness.stackexchange.com/questions/9454/how-can-i-figure-out-how-much-sleep-i-need