There are a pair arteries inside the neck vertebrae that supply blood to vital (subconscious) parts of the brain. Neck stiffness caused by stress, excessive computer use, head and neck trauma, bad posture, etc. reduce this blood flow to cause fatigue, headaches, dizziness, panic attacks, insomnia, and poor functioning of the immune system.
Neck massage, as well as yoga exercises, help to relieve that stiffness and rectify or prevent the above problems.
The brain floats in a fluid called CSF which also supplies glucose and some oxygen to the brain. Tightness of the neck muscles, reduce this fluid circulation, causing fatigue, headaches, poor concentration and memory, etc. Neck massage relieves the stiffness and improves the brain's functions.
In the erect position, the neck muscles are forced to contract for a long period of time and so they collect lactic acid which causes neckache. Neck massage alleviates that problem.
One should massage the neck while taking a shower. It is advised to have proper neck and upper back massages once or twice a month, especially for those who use computers a lot, are stressed, travel a lot, or have insomnia.