the protective mechanism
Dissociation is a disruption or change in connection: to memory, body, emotion, surroundings or identity. It can be mild, but it can also be intense and disruptive.
Most people know mild dissociation: arriving home on autopilot and not quite remembering the journey. In dissociative disorders, that disconnection is stronger, more frequent or more closely tied to trauma and stress.
For some people, dissociation was once a way to survive. When a situation was too much to fully experience, distance could become protection. Later, the same mechanism may keep happening even when it no longer feels useful or safe.
Dissociation is not always feeling nothing. Sometimes it is feeling too much, and somewhere in the system the lights dim so life can keep moving.
Many people use grounding: calmly naming where you are, holding something cold, placing your feet firmly on the floor, naming five things in the room out loud, or contacting a safe person. These are general ideas, not treatment. What helps differs from person to person.