Effects of Lighting Interventions to Improve Sleepiness in Night-Shift Workers: A Systematic Review and Meta-Analysis

Abstract

Shift work disrupts an otherwise normal circadian rhythm, which may result in sleepiness among night-shift workers. Artificial light has been shown to alter the light–dark cycle of shift workers and reset or phase shift the biological clock, improving nighttime alertness in workers. However, the effect of light therapy on improving sleepiness in nighttime workers has not been effectively confirmed in nursing clinical studies, and it is worth using relevant studies to provide the best evidence in any clinical setting. Systematic review and meta-analysis were used. The study was performed using PRISMA. Academic Search Complete, Embase, MEDLINE, the Cochrane Library, and CINAHL were searched, from the inception of each database to 27 December 2021. The Cochrane risk of bias tool was used to assess the methodological quality of each study. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were synthesized using a random-effects model to assess the efficacy of lighting intervention to improve sleepiness in night-shift workers. Sensitivity analysis followed by subgroup analysis was employed to examine heterogeneity. The meta-analysis was performed using Review Manager 5.4.1 software. A total of 14 studies from 7 countries were included. The overall result shows that lighting interventions significantly improved sleepiness. Further, the blue-enriched white light with a color temperature greater than 5000 Kelvin was effective in improving sleepiness of night-shift workers. This study unveils the emergent knowledge that light interventions with blue-enriched white were effective in improving sleepiness for night-shift workers, including nurses. This finding can be applied to ensure patient safety, reduce accidents, and improve work efficiency and job satisfaction. Nurses constitute the largest health professional workforce. We suggest that hospitals can insert blue-enriched white light equipment for night-shift healthcare providers. Several evidence-based suggestions are made for further consideration.

Hybrid effectiveness-implementation study of two novel spectrally engineered lighting interventions for shiftworkers on a high-security watchfloor

“…Many prior lighting countermeasures for shiftworkers have employed high-intensity light (≥1000 lux), which can be hard to tolerate [ 4 , 6 , 22 , 24–26 ]. In addition, lighting has often been in the form of off-the-shelf light boxes and/or retrofitted ceiling fixtures that can be challenging to implement in work settings, and can differ considerably in terms of not only spectral quality but also color temperature, intensity, spatial configuration, and other characteristics that may further influence physiological responses [ 4 , 8 , 54 , 77–81 ]. Thus, the use of lights that vary across multiple dimensions may conflate findings and lead to differential impacts that are independent of spectral quality per se, and may impact usability as well.…”

Consequences and management of sleep-wake rhythm disorders resulting from social jetlag and nightshifts

“…The results also suggest that reliable cutoff for days with SWD symptoms is 3 per month which gives a 3%-6% of SWD. [24,25] It is worth remembering about nurses who represent a particularly important group of healthcare providers, as they give 24-hour care in hospitals. A recent study involving shift nurses exhibits a higher incidence of mental health problems and burnout.…”

“…Some studies show that lighting interventions are not very effective in reducing sleepiness among nightshift workers. [24,[26][27][28][29][30][31][32][33] One of these studies investigated sleepiness among nurses during 3 consecutive nightshifts. It showed that bright light treatment reduces heavy 124 eyelids during night shifts as it delays circadian rhythm.…”

“…So, it is highly recommended to use light treatment at the hospitals and other workplaces with shift work schedules. [24] Conclusion "Social jetlag" is a broadly used term in a society and means the misalignment between local and circadian time. The possible causes of jetlag include travelling to different time zones and work schedules involving nightshifts.…”

“…[2,18,18,25] Melatonin supplementation, light exposure in the early morning or light therapy are among useful approaches to jetlag, however there are no specific recommendations about melatonin intake for shift workers [6,16] Despite that, it was examined that blue-enriched white light with a color temperature of minimum 5000 K was effective in improving the sleepiness of people working during the night. [24]…”