You probably know your circadian rhythm, the roughly 24-hour cycle that governs sleep and wakefulness. But inside each day, your body also runs shorter cycles called ultradian rhythms. One of them is often described as a wave of alertness that rises and falls roughly every 90 minutes or so.
The idea goes back to sleep researcher Nathaniel Kleitman, who proposed a “basic rest-activity cycle” that continues during the day, not just in sleep. The exact length varies between people and the research on daytime cycles is still debated, so treat 90 minutes as a useful rule of thumb rather than a precise law. Still, many people find that working in waves like this simply feels right.
Signs your focus wave is ending
- You reread the same sentence several times.
- You suddenly feel the urge to check your phone or grab a snack.
- You start yawning, fidgeting or feeling restless.
- Small mistakes creep in.
Most of us respond to these signals with another coffee or by pushing through. A short break often works better.
How to work with your ultradian rhythm
1. Plan focus blocks of 60 to 90 minutes
Instead of trying to concentrate for four hours straight, plan your hardest work in blocks of roughly 60 to 90 minutes. A weekly time-block planner makes these blocks visible, so your calendar matches the way your attention actually works.
2. Take real breaks of 10 to 20 minutes
A real break means stepping away from screens: a walk, a stretch, a glass of water, looking out of a window. Scrolling social media rarely gives your brain the rest it needs.
3. Put your best waves in your best hours
Not all waves are equal. Your strongest focus cycles tend to land in your daily peak, which depends on your chronotype. Early risers peak in the morning, night owls later in the day. Find yours with the Chronotype Quiz and give those waves to deep work.
4. Use low points for low-demand work
The dips are perfect for email, admin, tidying up and routine tasks. You are not wasting time; you are matching the task to the energy.
A sample wave-based workday
| Time | Block |
|---|---|
| 9:00 to 10:30 | Focus wave 1: most important task |
| 10:30 to 10:50 | Break: walk, water, no screens |
| 10:50 to 12:00 | Focus wave 2: second priority |
| 12:00 to 1:00 | Lunch |
| 1:00 to 2:00 | Low wave: email and admin |
| 2:00 to 3:15 | Meetings and collaboration |
| 3:15 to 3:30 | Break |
| 3:30 to 4:45 | Focus wave 3: lighter creative work |
Ultradian rhythm vs. Pomodoro
The Pomodoro technique uses 25-minute work sprints with 5-minute breaks. It is great for getting started and for tasks you are avoiding. Ultradian-style blocks are longer and better for work that needs deep immersion, like writing or problem-solving, where breaking every 25 minutes would interrupt your flow. Many people use both: Pomodoro to start, longer waves once they are rolling.
Listen to your own cycles
For one week, note when your focus naturally fades and how long you worked before it did. You may find your waves are closer to 60 minutes, or closer to 120. Adjust your blocks to your own rhythm. The point is not to obey a number. It is to stop fighting your brain and start working with it.
