Shift work and quality of sleep: effect of working in designed dynamic light

Abstract

Purpose To examine the effect of designed dynamic light on staff’s quality of sleep with regard to sleep efficiency, level of melatonin in saliva, and subjective perceptions of quality of sleep. MethodsAn intervention group working in designed dynamic light was compared with a control group working in ordinary institutional light at two comparable intensive care units (ICUs). The study included examining (1) melatonin profiles obtained from saliva samples, (2) quality of sleep in terms of sleep efficiency, number of awakenings and subjective assessment of sleep through the use of sleep monitors and sleep diaries, and (3) subjective perceptions of well-being, health, and sleep quality using a questionnaire. Light conditions were measured at both locations.ResultsA total of 113 nurses (88 %) participated. There were no significant differences between the two groups regarding personal characteristics, and no significant differences in total sleep efficiency or melatonin level were found. The intervention group felt more rested (OR 2.03, p = 0.003) and assessed their condition on awakening as better than the control group (OR 2.35, p = 0.001). Intervention-ICU nurses received far more light both during day and evening shifts compared to the control-ICU.ConclusionsThe study found no significant differences in monitored sleep efficiency and melatonin level. Nurses from the intervention-ICU subjectively assessed their sleep as more effective than participants from the control-ICU.Electronic supplementary materialThe online version of this article (doi:10.1007/s00420-015-1051-0) contains supplementary material, which is available to authorized users.

Bright environmental light improves the sleepiness of nightshift ICU nurses

“…The number of shift workers in industrialized nations is increasing to over 20% of the workforce [ 5 ]. In most intensive care units, nurses work 12-h shifts that consist of days and nights.…”

“…The American Academy of Sleep Medicine estimates the prevalence of SWSD to be 5–8%, with night shift workers being affected the most [ 3 ]. The significance is underscored when viewed in the context of industrialized nations, in which shift workers comprise more than 20% of the workforce [ 4 , 5 ]. For a field like healthcare that functions independent of the “time on the clock”, the prevalence of SWSD is likely much higher [ 6 ].…”

“…The reverse occurs upon darkness. Shiftwork perturbs circadian homeostasis, and considerable research has focused upon light therapy, circadian biology, and health [ 5 , 15 – 17 ]. Bright light even of short duration has been shown to impart acute positive effects in night shift working nurses, including heightened subjective alertness and reduced insomnia, anxiety, and depression [ 18 ].…”

The impact of shift work on intensive care nurses’ lives outside work: A cross‐sectional study

“…Disturbed circadian rhythms and sleep disorders have been found to be some of the most important factors for long‐term consequences of shift work (Matheson et al., ) but are also factors affecting physical and mental well‐being (Gamaldo, Chung, Kang, & Salas, ). Therefore, interventions that help nurses improve sleep such as light exposure at work (Bonde et al., ; Brawley, ; Czeisler, ; Jensen et al., ; Neil‐Sztramko et al., ) and instructions for best sleep practice (Matheson et al., ; Neil‐Sztramko et al., ) are also recommended.…”

“…The study was part of a larger intervention study examining the impact of dynamic light on nurses’ circadian rhythms (measured by melatonin profiles from saliva samples), quality of sleep (sleep efficiency, number of awakenings and subjective assessment of sleep; measured by sleep monitors and sleep diaries) and subjective experiences of sleep quality (measured by a sleep questionnaire survey) (Jensen et al, ).…”