We often discuss the importance of taking breaks to be more productive, but the folks at PayScale have put together a great explanation for exactly why you shouldn't work more than 90 minutes at a time. It all has to do with our basic rest activity cycle.
Photo by tookapic.
The Basic Rest Activity Cycle, also called BRAC, may be more familiar to most people as a term that describes the normal human sleep cycle, which is (roughly) 90 minutes in length, where you're close to wakefulness, descend into REM sleep, and then come back up again and start the process all over.
Of course, extrapolating this to waking activities like work is a bit of a stretch, but it's not a bad excuse, as PayScale notes:
We've known for more than 50 years that we sleep in 90-minute cycles. (If you have a sleep tracker, likely as a feature of an activity band, you might have noticed this yourself.) We move from light sleep, to deep sleep (and restorative REM state) in roughly 90-minute waves. About a decade after we learned about this natural sleep cycle, researchers began to realise that we follow a similar pattern in our waking lives as well.
… In response to this information, and in an effort to better understand productivity, Florida State University Professor K. Anders Ericsson and his colleagues studied "elite performers," folks who excelled in their field, whether they were musicians, athletes, or chess players. Ericsson discovered that uninterrupted practice in intervals of 90 minutes or less, with breaks in between sessions, worked best for maximizing productivity. Also, he noted that these folks rarely worked more than four-and-a-half hours in a given day.
"To maximise gains from long-term practice," Ericsson concluded, "individuals must avoid exhaustion and must limit practice to an amount from which they can completely recover on a daily or weekly basis."
By focusing on limiting our fatigue to a level that we can completely recover from in a timely way, we can help to maximise our time and our productive efforts. Perhaps thinking of work or projects in terms of how they can be blocked into 90-minute chunks could be a good place to start. Who knows, maybe with practice we could even build to keeping our active workdays under that four-and-a-half-hour maximum Ericsson recommended, too.
Of course, the whole idea has to be thoroughly tested and is by no means experimental fact or peer reviewed and published, but there are some interesting ideas here. It may be part of the reason that productivity methods like the Pomodoro Technique resonate with people so much, and why we always have to work a bit to get "in the zone," but only generally stay in it for a while before we snap out of it and know we should take a break. For more, hit the link below.