Just happened to come across an article about treating a stress headache with acupressure, which releases blocked energy (or qi), which can help relieve discomfort and disease:

Sit or lie down, close your eyes, and focus on relaxing. Using your thumbs, put pressure on the points under the base of the skull – located in neck hollows about three inches apart at the back of your head – known as the Gates of Consciousness (ooh!). Tilt your head back slowly and begin breathing deeply, allowing the weight of your head (and gravity) to match the force of your thumbs. Hold for three minutes. Meditate or practice deep relaxation for five minutes to prevent the pain from returning.

More info: aobta.org, the web site of the American Organization for Bodywork Therapies of Asia.