Absolutely nothing compares with sleep. Having about a full week of 8 hour sleep days behind me is when I'm at my absolute peak productivity. I spent years being sleep deprived (~6 hours/day). When I finally came to appreciate just how important being well rested is it absolutely changed my life.
Clicked in here to say exactly this. The only thing I would add might be obvious, that consistency is extremely important. Just getting enough actually isn't enough, consistent timing is essential.
My second most significant is probably reading in place of momentary distractions.
I'm applying nearly all my "free time" (what's left after the family, work, exercise and sleep that I consider essential) with an attack on my backlog of books.
I wiped my devices and rebuilt them with only the essentials - no more newsreaders or social apps and I've greatly limited my web browsing.
Not only am I working towards a goal and learning new things, I'm spending it on a book or two rather than 100s of throwaway articles and blog posts - all but eliminating "context-switching" as I feel like I can keep 2 or 3 concerns in mental cache and get the full value of the time I spend on each of them.
As someone who can never seem to catch up on his news-feeds or podcast lists (and I've pared those down more than once), this resonates with me. I wonder if I can cut each of those in half.
Reading a book vs. reading news sites trains your brain to focus, a capacity we all seem to have lost in the last decade due to excessive bite-sized-attention-grabbing apps.
My case is exactly the opposite of yours. I used to sleep 8 hours and take naps during the day and always felt exhaust.
But since I started to do at least 1 hour of exercises EVERY DAY (and for me is important to not miss any day), I sleep only 6 hours a day and is when I reach my peak productivity.
