Part VI · Protocol 1 — Focus
The 90-minute block, and why 25 minutes is not enough
Planning your day as six continuous hours of intense concentration is a fiction. Two real blocks beat eight hours of fragmented attention.
Alertness is not a straight line
Your level of alertness does not stay steady all day. It oscillates according to what are called ultradian cycles, lasting roughly 90 to 120 minutes — described as early as the 1960s by Nathaniel Kleitman and found in most mammals.
These cycles are most visible at night, where they structure the alternation of slow-wave and REM sleep phases. But they continue to modulate alertness, heart rate, core temperature, and that sensation of a slump in the early afternoon.
One honest caveat before the number becomes a rule: the ability to sustain directed attention for 90 to 120 minutes before quality drops is not absolute. The available data suggest an average window — one that varies widely from person to person and is heavily influenced by the previous night's sleep, caffeine, blood sugar and time of day. Four things, three of which are protocols elsewhere in the manual.
The rule that matters more than the duration
The depth of a block depends less on its length than on the rule you impose on yourself while it runs: one task only, no stray tab opened, notifications off, phone out of the room.
Every intrusion does not just cost the time it takes. Your attention needs several minutes to return to where it was. In practice, five real interruptions can consume the equivalent of thirty minutes of the block — which is how an hour of "work" produces fifteen minutes of output and nobody can say where the rest went.
What the block looks like in practice
Protocol
The 90-minute block
- Choose a window of 60 to 90 minutes, always at the same time if possible, when your alertness is at its best — often one to three hours after waking.
- Before you start, write a single observable target. Not "work on the report" but "draft section 3 up to subsection B."
- Phone out of the room, notifications off, one document open. If a stray idea pops up, write it on a separate sheet and return to the task.
- Start with a deliberately imperfect draft: the first five minutes are for getting in, not for producing.
- At the end of the block, stop cleanly and note the first action of the next block.
- Follow with fifteen to twenty minutes of a real break, with no high-stimulation screen.
Caution
If you are in sleep debt or going through a period of acute stress, a 90-minute block will probably be too long. Start with 40 minutes, then lengthen it gradually. The window is an average, not a target to reach regardless of your state.
The break is part of the protocol
Most people treat the break as the reward for the block, and take it on the phone — which is not a break but a change of stimulus, and often a more demanding one. The manual treats it as a separate protocol for a specific reason: consolidation happens during rest, not during effort. The rest that follows effort is not the absence of work. It is the part of the work you cannot skip.
Which is the pattern that runs through all seven pillars. Photoreceptors, adenosine, core temperature, blood glucose, the autonomic nervous system — every protocol in the manual is anchored to a known physiological mechanism rather than to a habit someone found inspiring. That is the difference between a manual and a list of tips: you can sequence a manual. Each protocol moves the baseline the next one works from, which is why the order is the product.
Continue
- Why you still feel tired after eight hours of sleepPart V, Protocol 1 — the block depends on the night before
- The best time to drink your coffeePart I, Protocol 11 — one of the four variables that set attention
- All five guidesSleep, energy, stress, metabolism, focus
This is one of sixty-three protocols
Ten in the focus pillar alone. The manual runs 102 pages across seven pillars, with an action box and a caution for every protocol — plus a 30-day programme that sequences them for you.
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