When sky blue comes to your mind, your body becomes lighter and fresher. Black represents the color of heartless matter and white is the color of an uninterrupted(boundless) and clear spirit. On the other hand, blue (sky blue) is one of the representative of the color revealed by the active occurrence among all the colors that exist between the extreme limit of matter(black) and the extreme limit of the clear mind(white). OK! Red is also proactive but different tone compared with blue. Blue rather control the activity of red. Not much to say like this because you know it by intuition. Blue (sky blue) is said to be the color of healing. Isn't it a color that represents the phenomenon of life like an active process of birth and rebirth of life body? Like is what we call the earth as a blue planet.
Healing is another face of purification. Healing has an opposite vector of the life force that turns back from the destination of death. As it be regarded as decay is to death and purification is to rebirth.
The man in sapphire blue by st. Hildegard von Bingen/Left, Medicine Buddha/Right