Ultradian Energy-Cycle Planner
Fit your day to the body’s ~90-minute waves of focus and fatigue — whole focus-then-rest cycles across your working window, with a scheduled timeline and a finish time.
Your energy-cycle plan
- Focus 09:00–10:30, then rest until 10:50
- Focus 10:50–12:20, then rest until 12:40
- Focus 12:40–14:10, then rest until 14:30
- Focus 14:30–16:00, then rest until 16:20
Working with the wave — a focused block, then a genuine rest — tends to hold energy better across a day than pushing straight through and crashing.
How the plan is built
One cycle is a focus block plus a rest. The planner divides your working window by that combined length to find how many whole cycles fit, then reports the total focus time, total rest, and any leftover minutes too short for another full cycle. Give it a start time and it schedules each block on the clock, from the first focus period to the final rest.
The goal is to align effort with the wave — work while alertness is high, recover in the dip — rather than grinding at a flat pace until you crash. Use the leftover time for shallow tasks or a longer break.
Frequently Asked Questions
What is an ultradian rhythm?
An ultradian rhythm is any body cycle that repeats more than once a day. The one that matters for focus is the basic rest–activity cycle first described by sleep researcher Nathaniel Kleitman: roughly 90-minute waves of rising and then falling alertness that continue through the waking day, not just during sleep. Work tends to feel easiest near the crest of a wave and hardest in the trough.
How long should a focus block be?
Long enough to ride one wave of alertness — around 90 minutes for many people, though the real length varies and yours might be 75 or 110. The idea is to do one sustained block, then stop before the trough drags your work down. This planner defaults to 90 but lets you tune the block to what you actually experience.
Why take a real rest between blocks?
Because the trough of the cycle is when the body signals for recovery, and pushing through it with more screen time borrows energy you then lack later. A genuine rest — moving, stepping outside, letting your eyes and mind wander away from work — lets the next wave build. Twenty minutes is a common choice, which is why it is the default.
Is the 90-minute figure exact?
No. Ninety minutes is a well-cited average, but ultradian cycles vary between people and across a day, and the science is still debated. Treat the plan as a scaffold to experiment with rather than a biological law — track how your own energy rises and dips, then set the block and rest lengths that match it.
Educational planning aid only — not medical advice. Ultradian cycle lengths vary between people and across the day; use the plan as a scaffold to experiment with and adjust to your own energy.