A relic of the Industrial Revolution, the eight-hour workday’s insistence on working long blocks of time with frew breaks isn’t great for how we work now. Dr. Travis Bradberry writes at Quartz about a better way to structure your work day to be productive:

the length of the workday didn’t matter much; what mattered was how people structured their day. In particular, people who were religious about taking short breaks were far more productive than those who worked longer hours.

The recommendation: Work an hour, then take a 15 minutes break. A real break, like going for a walk. Repeat as needed. It sounds like a lower frequency version of the pomodoro technique.