Emerson

he is not colorblind
just kidding
he probably got dizzy or you massaged a nerve ending that sent an impulse to him in a pain or discomfort way

Nina

During massage, muscles are contracted and relaxed, and this actually gets blood n your veins flowing more than normal and can affect all sorts of things like blood pressure and heart rate. It’s possible that a change in circulation could suddenly change the level of oxygen in the brain, causing some visual sensations. It’s analogous to seeing purple spots when you’re light-headed.

Ana

Shades of blue are sometimes seen by someone who has taken viagra. Perhaps he was close to the happy ending?

Hailey

There are a two major possible explanations.

The first is that often massage leads us to a relaxed and meditative state. Some people see flashes of different colors when they meditate. Thus - it is the relaxed state of meditation that leads to some people seeing flashes of different colors when receiving a massage, even with the eyes closed.

The other explanation is that changes in blood flow can affect brain chemistry. Of course, the same changes in brain chemistry can happen when meditation changes blood flow. The brain chemistry can influence what we hear, see, and feel.

There is a degree of debate as to whether colors, visions, etc are simply brain chemistry or something beyond the physical realms of existence. I would suggest that both can be at play independently or at the same time.