90 Minute Deep Work Timer
Free online 90-minute focus timer. No signup required.
About the 90-Minute Timer
The 90 minute timer is based on the ultradian rhythm research of sleep scientist Nathaniel Kleitman, who discovered that the human body operates on 90-minute cycles of high and low alertness throughout the day. Working in 90-minute blocks aligns your focus sessions with your body's natural energy oscillations. Peak performance researcher Anders Ericsson found that elite performers across domains — violinists, chess players, athletes — typically practice in sessions of 60-90 minutes, rarely exceeding 4 hours of deep work per day.
Best for
Deep work, flow states, thesis writing, complex engineering
Tips for Your 90-Minute Session
- This is the most advanced technique — build up to it from shorter sessions
- Take a full 20-30 minute break after each 90-minute session
- Most people can sustain 2-3 quality 90-minute sessions per day — that's elite-level output
- Protect these sessions fiercely: no notifications, no interruptions, no exceptions
Want to track your progress?
Sign up for Peazehub to save your sessions, build streaks, compete on leaderboards, and join study groups. All for a one-time payment of $9.99.