1.Scalp is also stiff

The area around the head is made up of muscles. We often have stressful thoughts and our head muscles become tense and tight. In this state, blood circulation decreases, and the necessary nutrients and oxygen for your hair cannot reached properly. As a result, your hair becomes thinner and loses its luster. 
Obacchi recommends :
head massage as a stretching exercise for your head.

2. Blood Flow and Detox

Head massage has the effect of moving the muscles around the head that are usually inactive, helping to flush out accumulated waste. 
Obacchi recommends:
scalp detoxification which is hydration, drinking plenty of water after head massage to help eliminate waste toxins from the body.