Ultradian Rhythms
Natural 90-120 minute cycles of energy and focus that occur throughout the day.
Also known as: 90-minute cycles, BRAC cycles, Basic rest-activity cycle, Energy cycles
Category: Concepts
Tags: time-management, productivity, energy, focus, biology, techniques
Explanation
Ultradian rhythms are biological cycles that occur multiple times within a 24-hour period, most notably the 90-120 minute cycles of alertness and energy we experience throughout the day. Research by sleep scientist Nathaniel Kleitman discovered that these same cycles governing our sleep stages continue during waking hours, creating natural peaks and troughs in our cognitive performance. During each cycle, we move from higher to lower alertness, with the first 90 minutes typically being our most focused period. Understanding ultradian rhythms helps optimize productivity by suggesting we work in focused 90-minute blocks followed by 15-20 minute breaks for recovery. This aligns with findings about deep work and flow states, which tend to occur within these natural attention windows. Signs you've reached the end of an ultradian cycle include: increased difficulty concentrating, hunger, drowsiness, or fidgeting. Rather than pushing through with caffeine or willpower, taking a genuine break allows your brain to reset for the next cycle of peak performance.
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