Caffeine is a stimulant. I find that after a cup of coffee I’m OK for about 4 hours. I try to schedule my focus time during the first half of the day, and then allow the second half to be research time.
While I’m working, I tend to have a list of three things I want to work on. If thing.1 stalls, I can open thing.2 and then thing.3. I can’t do more, or I’ll forget to go back to thing.1. If all three things stall, I grab a bit of dopamine via a video game or SM and then go back to thing.x where thing.importance is max.
I also have a couple of backup tasks in case I can’t work on the big three. There’s always documentation and expense reports.