Shift workers - about one in five Americans - work non-traditional hours (not the typical hours of 9 a.m. to 5 p.m. ). Difficulty falling asleep is a common effect as is obtaining quality sleep during the day hours. Women who work on the night shift get less sleep and more disrupted sleep. Shift workers, in general, report more sleep-related accidents and illnesses. Night and rotating shifts can put a strain on a family when less time is available to meet family/home responsibilities and enjoy recreational and social activities. Female shift workers also suffer irregular menstrual cycles, difficulty getting pregnant, higher rates of miscarriages, premature births and low birth-weight babies more than regular day working women, according to several large studies. Still, most shift-working women do have normal, healthy babies. Changes in exposure to light and lost sleep caused by shift work may have biological or hormonal effects that are not yet entirely understood. One large study of women who worked night shifts over a 3-year period found a 60% greater risk for developing breast cancer. Women shift workers should consult their doctor if experiencing menstrual difficulties, infertility, pregnancy or other medical conditions/ problems