alt=The face and horns of a ram with brown wool|thumb|Irritable male syndrome has been documented in Soay rams.
Irritable male syndrome (IMS) is an annual behavior pattern that has been described in Soay sheep and other mammals with a strictly seasonal breeding pattern and described in a 2002 literature review of animal behavior by Gerald A. Lincoln. IMS is a striking feature in mammals with seasonal breeding patterns; it manifests at the end of the mating season. The term has been adapted to refer to disagreeability observed in aged human males.
Characteristics
Soay sheep mate for five weeks during November and December each year, and give birth five months later in the spring. The rams' testosterone levels soar during the late autumn mating season. In the winter, testosterone levels fall and they stop mating. As their testosterone levels fall, the rams become more nervous and withdrawn, striking out irrationally. a concept he had earlier popularized. According to Diamond, andropause is a change of life in middle-aged men, which has hormonal, physical, psychological, interpersonal, social, sexual, and spiritual aspects. He says that this change occurs in all men and may occur as early as age 45 to 50 and more dramatically after the age of 70 in some men, and that women's and men's experiences are somewhat similar phenomena. Thomas Perls and David J. Handelsman, in a 2015 editorial in the Journal of the American Geriatrics Society, say that between the ill-defined nature of the diagnosis and the pressure and advertising from drug companies selling testosterone and human growth hormone, as well as dietary supplement companies selling various "boosters" for aging men, the relevant medical condition, late-onset hypogonadism is overdiagnosed and overtreated. Perls and Handelsman note that in the US, "sales of testosterone increased from $324 million in 2002 to $2 billion in 2012, and the number of testosterone doses prescribed climbed from 100 million in 2007 to half a billion in 2012, not including the additional contributions from compounding pharmacies, Internet, and direct-to-patient clinic sales."