One extremely important topic wasn't mentioned here - the impact of sunlight. For those, who feel that sunlight is crucial for their cognitive and (more important) emotional base-level, I recommend a great book by Linda Geddes - "Chasing the sun"[1].

One of important findings in the mentioned book was that blue light (as emitted by computer and smartphone screens) inhibits melatonin excretion and thus have negative impact on the quality of sleep and makes it harder to fall asleep. I replicated author's experiment and haven't used smartphone & computer after 8PM (for about a week) and my sleep quality improved greatly.

[1] https://www.goodreads.com/book/show/42603316-chasing-the-sun