Inertia, in the neurodivergent sense, describes a profound difficulty starting, stopping, or changing tasks that goes beyond ordinary procrastination or avoidance. The term borrows from physics: an object at rest stays at rest, and an object in motion stays in motion.

For many Autistic, ADHD and AuDHD people, this maps closely onto daily experience. Researchers describe two forms. Inertial rest is the difficulty initiating action, even when the intention is clear and the task is simple. Inertial motion is the difficulty stopping or disengaging once something has begun, especially when focus is deep. We can experience both kinds of inertia, often swinging between extremes: frozen and unable to start, or locked in and unable to pull away.

A 2023 qualitative study of Autistic adults described inertia as a double-edged sword. While some participants called it “the single most disabling part of being Autistic,” affecting work, relationships, and basic self-care, others described inertial motion during meaningful activity as bringing intense joy, creativity, and flow, with one person calling it “the most amazing feeling in the world.”

It can be both the thing that keeps us stuck and the thing that lets us go deep. Like many aspects of the Autistic or ADHD experience, inertia is complex: a source of friction and deep joy.