[__mbm__]

Keep it up.

I had a similar experience. Even through my PhD at a top-tier school in applied math, I didn't do "all-nighters" or cram sessions. In fact, after my first 2 years of PhD (where I regularly put in 80 hours a week because of the course load), I toned it down to 40-50 hours. I also didn't use performance enhancing drugs meant to treat things like ADHD.

I did (and still do) use a lot of coffee in the mornings. I also recommend going out to bars to have those petty discussions, so that socializing is reliably separated study.