By Russel Kirkby, MD, and Brian s. Alper, MD, MSPH

Dr. Kirkby is a family medicine physician in private practice in Pietermaritzburg, KwaZulu-Natal, South Africa, and an editor for DynaMed. Dr. Alper is medical director of clinical reference products for EBSCO Publishing, in Ipswich, Mass., and editor-in-chief of DynaMed (www.dynamicmedical.com), a database of comprehensive updated summaries covering nearly 2,000 clinical topics. Description • Involuntary nighttime…