some work needs time to unfold.
you sit down with a difficult problem, and the first twenty mins might be spent simply figuring out where to begin.
then something clicks.
you start seeing connections.
the work gets quieter.
this is where a longer focus session can be useful.
a 90 min session gives you enough uninterrupted space to settle into demanding work without constantly checking the clock.
but there's something important to say here.
science doesn't prove that exactly 90 mins is the perfect length for everyone.
research on human performance has explored roughly 90 min ultradian rhythms, but the evidence isn't consistent. one study specifically investigating cognitive performance found no significant 90 min periodicity.
so I wouldn't treat 90 mins as a biological rule.
I'd treat it as a useful container.
for work that carries a heavy cognitive load, that extra space can be valuable.
complex architecture.
difficult programming.
deep research.
writing that requires sustained thinking.
creative work where the first few mins are often just the beginning.
a simple structure could be:
90 mins of focused work.
then stop.
get up.
walk around.
drink some water.
let your mind move somewhere else for a while.
research on work breaks suggests that rest periods can affect fatigue and attention, although the ideal timing depends on the task and person.
for me, the biggest benefit of a longer session isn't trying to squeeze more work out of the day.
it's removing the feeling that I have to rush.
there is enough time to think.
enough time to get stuck.
enough time to find my way back.
I've also been working on a 90 min deep focus session with soft ambient music, gentle rain, and a mindful bell every 20 mins.
the bell isn't there to interrupt the work.
it's a tiny reminder.
am I still here?
if my attention has wandered, I can simply return.
try the 90-min deep work session →. soft ambient music, gentle rain, and a mindful bell every 20 mins.
for now, think of 90 mins as an invitation rather than a rule.
some work deserves a little more room.
and sometimes, that room is where the good thinking finally begins. 🤎
p/s: if 90 mins feels like more time than you need, the 50 mins focus block offers a shorter rhythm to try.
and if getting started is the hardest part, the 25 mins focus block might be a gentler place to begin.
this is one small part of how I think about deep work, for the days when the thinking needs more space. if you'd like, you can read the rest.
