Andropause is often defined as the male equivalent of menopause in women. It occurs around the age of 45, when testosterone production begins to decline or even stop altogether, resulting in a gradual decrease in a man's ability to function sexually. The word "andropause" is derived from the Greek words "andros" or "man" and "pausis", meaning "pause" or "temporary stop". The discomfort associated with andropause can vary from person to person, but generally includes decreased sexual appetite or libido, ongoing fatigue, depression, irritability, mood swings, loss of strength and/or muscle mass, hot flushes and interrupted sleep cycles. Some of these discomforts can occur during drug treatments.