Raynaud's phenomenon is typically induced by cold or emotional stress and is often relieved by heat. It affects between 5 and 10 percent of the population and predominantly occurs in young and middle-aged women. In most cases, the condition is mild and idiopathic. In others, an underlying abnormality, such as a connective tissue disorder, or exposure to repetitive mechanical trauma precipitates the condition. Treatment is directed at the underlying cause, if known. Empiric therapy includes avoidance of cold exposure, heat applications and drug therapy, most often calcium channel blockers.