The Effectiveness of Light/Dark Exposure to Treat Insomnia in Female Nurses Undertaking Shift Work during the Evening/Night Shift

Abstract

The present study investigated whether bright light exposure during the first half of the evening/night shift combined with light attenuation in the morning is effective in improving sleep problems in nurses undertaking rotating shift work who suffer from clinical insomnia. This was a prospective, randomized control study. The Insomnia Severity Index (ISI) and the Hospital Anxiety Depression Scale (HADS) were used to evaluate insomnia and anxiety/depression severity, respectively. Female hospital nurses on rotating shifts during the evening or night shift with an ISI score > 14 were enrolled. Subjects in the treatment group (n = 46) were exposed to bright light at 7,000-10,000 lux for ≥ 30 minutes. Exposure was continued for at least 10 days during 2 weeks, and the subjects avoided daytime outdoor sun exposure after work by wearing dark sunglasses. Subjects in the control group (n = 46) were not exposed to bright light, but also wore sunglasses after work. Statistical analyses were performed to examine group differences and differences across treatments. After treatment, the treatment group showed significant improvements in the ISI score and the HADS total and subscale scores as compared with pre-treatment. The ISI, HADS, and subscales of the HADS scores were significantly improved across treatments in the treatment group as compared with the control group. The design of this study is easy to put into practice in the real world. This is the first study to document that a higher intensity and briefer duration of bright light exposure during the first half of the evening/night shift with a daytime darkness procedure performed in rotating shift work female nurses suffering from clinical insomnia could improve their insomnia, anxiety, and depression severity.