This is a really hard question. One that I'm still figuring out. For me, the question is about how much sleep I need in order to perform optimally at study, or whatever. I seem to feel tired most of the time... I'm only just learning to separate out the feeling of tiredness (don't matter) from my physiological ability to function (what does matter).

I think I mostly get too much sleep. Probably around 9 hours. My alarm wakes me up but unless I have a physical reason to get up (or I'll be late for an external committment) my half-asleep self always decides it is far too tired to wake up and there is no point feeling like that forever and the only solution is to go right back go sleep... So back to sleep I go and I have trouble getting to sleep that night because I'm not tired yet... And before I know it I'm not getting to sleep until 3am and I'm waking up around 10 or 11 or 12... And feeling tired all the time...

At various points I've had deadlines that meant I had less sleep because I literally had to work... I've felt... A little buggy eyed. A little hyper. But I was able to really crank through the work... And I crashed easily in a deep sleep at night... And woke up 5 minutes before my alarm... Some of the time, anyway.... How many hours? I think more like 7 or 8...

It depends so much... On how hard I work at the gym... On how stressful the work is... On whether I'm fighting off something... I know that probably once a week... Once every second week... I basically need a day in bed to recover from life... But doing that... I can't remember the last time I had a cold / flu / got sick. So... I guess that indicates something...