There is an old Chinese Medicine expression that says “disharmony of the liver is the cause of 10,000 illnesses.”  The liver is so important because it is responsible for the smooth circulation of vital energy called qi (pronounced "chi").  When this vital energy stagnates, blood and other bodily fluids lack there normal energy and ability to bring balance and health.  Vital energy stagnation left untreated can lead to the formation of masses and fibroids.  If blood stagnates in the chest then the lungs and heart will be affected.  Stress and anxiety are common symptoms of vital energy stagnation.

In addition to the liver vital energy channel, the gallbladder vital energy channel plays an important role in stress and anxiety.  The gallbladder energy channel runs over the shoulders, up the neck, and on the sides of the head.  Stress causes tension buildup in the shoulders, neck, and sides of the head, which interferes with the overlapping liver vital energy channel.  Therefore, many people that are experiencing stagnation of liver energy are also experiencing stagnation of the gallbladder energy channel.  The liver vital energy channel is supremely important because it is the one organ capable of affecting all of the other organs.

Acupuncture and herbs are highly effective in freeing the stagnation of vital energy channels thereby reducing stress and anxiety.  Free flowing vital energy also promotes balance, health, and well-being by permitting the body to heal itself. 
Interestingly, a study published in Anesthesiology (June 2003) used ear acupressure to relieve stress and anxiety in patients being transported by ambulance to a hospital.  In some patients real acupuncture points were used while in others bogus points were used.  On arrival at the hospital, the stress level in the acupuncture group decreased 66%.  In contrast, the stress level in the bogus points group increased 10%.

Useful Links:

WebMD: Acupuncture Makes Moms Less Anxious, Resulting in Less Anxiety in Children

The Journal of Nervous and Mental Disease
Acupuncture for Posttraumatic Stress Disorder: A Randomized Controlled Pilot Trial. 
Conclusion: Acupuncture may be an efficacious and acceptable non-exposure treatment option for PTSD.

Proceedings of the National Academy of Sciences of the U.S.A.
Chronic stress, glucocorticoid receptor resistance, inflammation, and disease risk. 
Conclusion: Chronic stress may raise the risk of sickness by fostering resistance to cortisol.