What is BRAC basic rest activity cycle?

Example: A software engineer notices she writes her best code in focused bursts that last about 90 minutes before her attention starts to fragment. She used to push through the fragmentation — forcing another 45 minutes of degraded work before finally breaking. After learning about ultradian rhythms, she restructures her day: 90 minutes of deep coding, then a 15-20 minute genuine break (walk, stretch, casual conversation — not email). She tracks her output for a month and discovers she produces more quality code in three 90-minute cycles with real breaks than she did in six hours of continuous desk time. The total clock hours are fewer. The total output is higher. The end-of-day exhaustion is lower. She did not become a better programmer. She became a better allocator of her existing capacity by working with her biology instead of against it.

This concept is part of Energy Management in the How to Think curriculum.