Light Exposure and Sleep-Wake Pattern in Rapidly Rotating Shift Nurses

ABSTRACT

OBJECTIVES: Shift workers are at risk for various sleep and health-related problems. To investigate light exposure and sleep-wake pattern according to shift schedules in shift workers. METHODS: We enrolled 12 full-time, rapidly rotating three-shift female nurses (age 26.4±4.01 years). They completed sleep logs and actigraphy monitoring of sleep-wake parameters, light exposure, and activity levels for over 14 days (mean numbers of night shifts 2.5). RESULTS: Before beginning shift work, participants were healthy and had no history of hypnotics. One third of participants (33.3%) had clinically significant insomnia-related symptoms (insomnia severity index ≥15, mean 14.0). Reported health problems were irregular menstruation cycles (75%), nightmares (25%), and irritable bowel syndrome (16.7%). Mean sleep time was less than 6 h regardless of the shift periods and wakefulness after sleep onset was prolonged more than 30 min. Light exposure in night-shift periods was the lowest during working hours and the highest during non-working hours. Activity levels were not different during working hours throughout the schedules. CONCLUSIONS: Fast-rotating shift nurses sleep less and unsatisfactorily. Health-related problems were frequent in shift nurses. Rapidly rotating shift schedules and related inappropriate light exposure may be detrimental to sleep and health in shift workers.