Cataclysma

What are the optimal time blocks of sleep to ensure you feel the best when you wake up? I've heard various answers from a few different sources but I usually aim for 8 hours sleep, and then if not I've heard 4 hours is also an acceptable amount.

Also, is it true that if I were to sleep for longer than the optimal amount (e.g 10 hours if 8 was optimal), then that 2 hours extra sleep would actually make me feel worse?

Ah, so you'd say the actual duration of time doesn't necessarily matter that much on its own, but also the time of day? Okay that's pretty cool, thanks for the help!