The effect of blue-enriched white light on cognitive performances and sleepiness of night-shift workers: A field study

Motamedzade, Majid; Golmohammadi, Rostam; Kazemi, Reza; Heidarimoghadam, Rashid

doi:10.1016/j.physbeh.2017.05.008

Cited by 77 publications

(87 citation statements)

References 35 publications

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“…It can also enhance sleep quality and perceived functioning outside the work place [ 7 ]. It has also been demonstrated that exposure to blue-enriched white light during night shift works declines sleepiness and salivary melatonin to a great extent and causes improvement in cognitive performance [ 8 ].…”

Section: Introductionmentioning

confidence: 99%

The effect of a blue enriched white light on salivary antioxidant capacity and melatonin among night shift workers: a field study

Kazemi

Hemmatjo

Mokarami³

2018

Ann of Occup and Environ Med

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BackgroundBecause of their positive impact on individuals’ performance and alertness, blue enriched white light sources are gaining popularity in households and industries. However, these sources of blue light spectrum may cause oxidative stress. On the other hand, there are no empirical studies investigating the negative effect of blue enriched white light on oxidative stress. Thus, the current study aimed at empirical assessment of the effect of such light sources on oxidative stress among night shift workers.MethodsThe study, which adopted a cross-sectional design, focused on 30 control room operators of a petrochemical complex. The subjects followed a shift-work schedule comprising 7 night shifts, 7 day shifts, and 7 days off. The subjects were exposed to 6500 K, 3000 K, and 17,000 K light sources (which have various degrees of blue light) during three consecutive work cycles, with each cycle lasting for 7 nights. In each light condition, three salivary measurements were conducted (at the beginning, in the middle, and at the end of the shift). The measurements were used to assess catalase (CAT), total thiol molecules (TTG), and total antioxidant capacity (TAC), and melatonin.ResultsThe results of repeated measures ANOVA showed that there was no significant difference among various light conditions with regard to salivary biomarkers (catalase, total thiol molecules, and total antioxidant capacity). There was however a significant difference between 3000 K and 17,000 K conditions with regard to the concentration of salivary melatonin (p = 0.001).ConclusionGiven that there was no significant difference among various light conditions in terms of biomarkers, it is concluded that using sources of light with high color temperature can be recommended. Nonetheless, because of the limitations of the present study (e.g. short period of intervention), it is suggested that care should be exercised in using such light sources.

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Section: Introductionmentioning

confidence: 99%

The effect of a blue enriched white light on salivary antioxidant capacity and melatonin among night shift workers: a field study

Kazemi

Hemmatjo

Mokarami³

2018

Ann of Occup and Environ Med

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“…Motamedzadeh et al showed that during the sustained attention task, exposure decreased both omission errors and reaction time. This difference may come from confounding factors, which were ignored in the study of Motamedzadeh et al (16).…”

Section: Discussionmentioning

confidence: 97%

Exposure to Blue Light Emitted from Smartphones in an Environment with Dim Light at Night Alters the Reaction Time of University Students

et al. 2019

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Background: Substantial evidence now indicates that exposure to visible light at night can be linked to a wide spectrum of disorders ranging from obesity to cancer. More specifically, it has been shown that exposure to short wavelengths in the blue region at night is associated with adverse health effects such as sleep problems. Objectives: This study aimed at investigating if exposure to blue light emitted from common smartphones in an environment with dim light at night alters human reaction time. Methods: Visual reaction time (VRT) of 267 male and female university students were recorded using a simple blind computerassisted test. Volunteer university students, who provided their informed consent were randomly divided into two groups of control (N = 126 students) and intervention (N = 141 students). All participants were asked to go to bed at 23:00. Participants in the intervention group were asked to use their smartphones from 23:00 to 24:00 (watching a natural life documentary movie for 60 minutes), while the control group only stayed in bed under low lighting condition, i.e. dim light. Just before starting the experiment and after 60 minutes of smartphone use, reaction time was recorded in both groups. Results: The mean reaction times in the intervention and the control groups before the experiment (23:00) did not show a statistically difference (P = 0.449). The reaction time in the intervention group significantly increased from 412.64 ± 105.60 msec at 23:00 to 441.66 ± 125.78 msec at 24:00 (P = 0.0368) while in the control group, there was no statistically significant difference between the mean reaction times at 23:00 and 24:00. Conclusions: To the best of the authors' knowledge, this is the first study, which showed that exposure to blue-rich visible light emitted from widely used smartphones increases visual reaction time, which would eventually result in a delay in human responses to different hazards. These findings indicate that people, such as night shift or on call workers, who need to react to stresses rapidly should avoid using their smartphones in a dim light at night.

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“…It is well accepted that melatonin suppression is required to affect alertness at night [5758]. However, recent studies have shown that melatonin level is low during the daytime, and light-induced alertness is not always mediated by the melatonin suppression [141759].…”

Section: Discussionmentioning

confidence: 99%

Non-Image Forming Effects of Light on Brainwaves, Autonomic Nervous Activity, Fatigue, and Performance

Askaripoor¹,

Motamedzade²,

Golmohammadi³

et al. 2018

Journal of Circadian Rhythms

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Fatigue and sleepiness are one of the main causes of human errors and accidents in the workplace. The empirical evidence has approved that, in addition to stimulating the visual system, light elicits brain responses, which affect physiological and neurobehavioral human functions, known as the non-image forming (NIF) effects of light. As recent evidences have shown the positive effects of red or low correlated color temperature white light on alertness and performance, we investigated whether exposure to 2564 K light could improve subjective and objective measures of alertness and performance compared with 7343 K, 3730 K, and dim light (DL) conditions during the daytime. Twenty two healthy participants were exposed to the light while they were performing a sustained attention task and their electroencephalogram (EEG) and electrocardiogram (ECG) were recorded. Both 2564 K and 7343 K conditions significantly reduced EEG alpha-power compared with the DL and 3730 K conditions. Moreover, the 2564 K, 7343 K, and 3730 K conditions significantly reduced subjective fatigue, sleepiness and increased heart rate and performance compared with the DL condition. Furthermore, the effects of light conditions on alertness and performance varied over the day so that more effective responses were observed during the afternoon hours. These findings suggest that light interventions can be applied to improve daytime performance.

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The effect of blue-enriched white light on cognitive performances and sleepiness of night-shift workers: A field study

Cited by 77 publications

References 35 publications

The effect of a blue enriched white light on salivary antioxidant capacity and melatonin among night shift workers: a field study

The effect of a blue enriched white light on salivary antioxidant capacity and melatonin among night shift workers: a field study

Exposure to Blue Light Emitted from Smartphones in an Environment with Dim Light at Night Alters the Reaction Time of University Students

Non-Image Forming Effects of Light on Brainwaves, Autonomic Nervous Activity, Fatigue, and Performance

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