Why I use 90-minute time blocks of work
Interesting that I am going to be writing about 90-minute time blocks and work rhythms when last week my work rhythm was completely out of whack! Life sometimes throws you curve balls and you just have to roll with it and do the best you can - that was my week last week. But this week is a new week and I am back to doing my best to stick to my usual work practices and writing this newsletter in my first 90-minute time block for the day.
When I shared What my work schedule looks like Lulu left a comment on the post about the 90-minute blocks so I said I would share more about why I structure my day that way.
While you are most likely familiar with the term circadian rhythm - rhythms that are physical, mental, and behavioral changes that follow a 24-hour cycle you may not be familiar with the term ultradian rhythm. An ultradian rhythm is a recurrent period or cycle repeated throughout a 24-hour day which is approximately 90 minutes in length.
The basic rest–activity cycle (BRAC) was first documented in 1960s and Nathaniel Kleitman defined it as a physiological arousal mechanism in humans occurring during both sleep and wakefulness. The below diagram from Fast Company illustrates the concept.
This concept has been confirmed if further studies and reviews including this one here which summarised:
This review furnishes data in support of the suggestion that an ultradian basic rest-activity cycle is involved in the functioning of the central nervous system and manifests itself in the alternation of non-REM and REM sleep and a similar periodicity in wakefulness.
This means that as much as we might like to think that we can focus solidly for hours on end doing deep work our brain just doesn’t have the capacity to do that. It has peak time and it needs breaks. Yes, you can sit in front of a computer screen and do work for hours on end but not all of it is deep work - work that requires concentration and solid focus and work that is of a high level.
With this knowledge, I have structured my work days [paywall break]