[Hot flashes] are the prime cause of sleep disruption in women over age fifty, Suzanne Woodward of Wayne State University School of Medicine reports. Her studies show that hot flashes in sleep occur about once an hour. Most prompt an arousal of three minutes or longer. Independently of their hot flashes, women who have them still awaken briefly every eight minutes on average. The sleep process dramatically blunts memory for awakenings, Woodward said, and in the morning women seldom realize how poorly they slept. Instead, they often focus on the daytime consequences of poor sleep, which include fatigue, lethargy, mood swings, depression, and irritability. Many women and their doctors, Woodward said, dismiss such symptoms as "just menopause." This is a mistake, she suggested, because treatment can reduce or eliminate hot flashes, aid sleep, relieve other symptoms, and improve a woman's quality of life. Treatment also helps keep frequent awakenings from becoming a bad habit that continues after hot flashes subside.