Shiftworkers have more complaints in three specific areas: sleep-wake disorders, gastrointestinal disorders, and cardiovascular disorders. After 1 to 4 months of effective shiftworking, more than 50% of shiftworkers leave shiftwork after suffering from fatigue, sleep disturbance, and other problems. In addition, older workers seem less able to adjust to shiftwork and are more likely to leave sooner. Three main factors influence the ability to predict adjustment to shiftwork: rigidity/flexibility of sleeping habits; ability/inability to overcome drowsiness; and morningness/eveningness. Occupational health nurses can influence shiftwork policy and workers' health through health promotion policies aimed at predicting which workers might be less tolerant of shiftwork, scheduling shiftwork so it follows the sun, and providing early diagnosis and rapid treatment to workers with symptoms that need management.