If the neck is stiff and tight, blood flow to the brain is constricted and this can result in mental fatigue. Unfortunately, many of us assume a poor posture when we are doing concentrated mental work.
Sit in a straight-backed chair. Place your thumbs behind the ears and just under your skull on each side. Relax your head back into your hands and against the chair back. Now slide your thumbs towards the back of your head. Stop just before you come to the thick muscle band — this is the acupoint. Your thumbs will be about 2 to 3 inches apart. Massage for about one minute. You can also do this massage lying on your back.
— from Healing Self-Massage by Kristine Kaoverii Weber, Collins & Brown, 2005