[eveith]

For most of my life, if I wanted to be productive, I aimed for 10h of sleep. Yes, really, ten hours. There is nothing like a good amount of sleep to make you productive. If its about achieving a certain goal, without pouring a specificed amount of hours into it every day, it is the best solution to let your brain refresh every night as much as it can. I don't hold any self-optimization approaches in high esteem; I found that, indeed, nothing helps as much as an healthy amount of sleep. This is not only important for my brain, but also for my stomach, and, especially, my eyes, I have found.

When "working a specified amount of hours every day at a minimum" is the modus operandi, I tend to make sure I get at least 8 hours of sleep at night.

Recreational days are strictly exempt from this policy. If my intellectual output does not matter, e.g., during holidays, I do not care whether I sleep 7 or 12 hours, then I strictly care about my well-feeling only. This might indeed involve vast amounts of cheese, red wine, and whisky. ;-)