The entrainment and synchronization of mental and physical states is the felt sense that you experience similar mental and physical states as the attachment figure. It is one of the nine factors that brings about secure attachment.
It plays an important part in bonding process and helps people emotionally co-regulate.
This is especially important as it helps with emotional regulation and the sense of belonging.
The sense of belonging helps militate against feeling socially isolated and alienated which is a common schema in people with insecure attachment.
The capacity to emotionally self-regulate could be the single most important outcome of secure attachment in childhood.
If it’s not learned in childhood it can be learned in adulthood. It just takes time. These types of meditations here help train that skill.