Cognitive load comes from John Sweller's cognitive load theory, originally about learning. Working memory can only hold a few things at once; everything you are trying to keep in mind — the task, open loops, notifications, an unclear plan — competes for that small space.
Why it matters
Deep work needs most of your working memory for the problem itself. Clutter in your head and on your screen takes capacity away from the work, even when you are not consciously attending to it.
How to apply it
- Externalise: write down plans, next steps and open loops.
- Close everything not needed for the current task.
- Break complex work into steps you can hold one at a time.
- Keep one task per focus block.