Whilst visiting a family with a special needs child, we noticed that the child was very nervous and was acting up. The mother said: Be right back! And took the child to the bedroom to change her undershirt into the "newfangled 'compression shirt'" she had just received from the Physical Therapist to try out. The difference was astounding: the child became calm, friendly and happy, participating in whatever was going on!!
I had always loved undershirts that "hugged". And now I found out why! How does it work? I dunno. But it does.