Lisa Marshall,
‘Just the two of us: Holding hands can ease pain, sync brainwaves’,, University of Colorado Boulder, Regents of the University of Colorado (Feb. 28, 2018)

Empathetic touch

Reach for the hand of a loved one in pain and not only will your breathing and heart rate synchronize with theirs, your brain wave patterns will couple up too, according to a new study. (…) The study (…) also found that the more empathy a comforting partner feels for a partner in pain, the more their brainwaves fall into sync. And the more those brain waves sync, the more the pain goes away. (…) It appears that pain totally interrupts this interpersonal synchronization between couples and touch brings it back. (…) Empathetic touch can make a person feel understood, which in turn – according to previous studies – could activate pain-killing reward mechanisms in the brain. (…) Interpersonal touch may blur the borders between self and other.