The autonomic nervous system controls the constriction and dilation of the blood vessels. This system operates in two distinct and opposing ‘modes’: sympathetic (associated with alarm and stress) and parasympathetic (associated with relaxation and recovery). In Raynaud’s, inappropriate or exaggerated sympathetic signals reach the affected regions. Acupuncture can prompt a switch in autonomic modes, and has found use in several conditions related to stress and vascular tone. Acupuncture can help decrease the frequency and severity of the vascular spasms of Raynaud’s.