Non-image forming effects of illuminance and correlated color temperature of office light on alertness, mood, and performance across cognitive domains

Ru, Taotao; Kort, Y.; Smolders, K.C.H.J.; Chen, Qingwei; Zhou, Guofu

doi:10.1016/j.buildenv.2018.12.002

Cited by 125 publications

(87 citation statements)

References 79 publications

(184 reference statements)

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“…In the current study, improvements were not observed in tests of vigilance and reaction time in these modestly sleep-restricted participants. While these findings are in contrast to previous reports of positive effects of short wavelength-enriched light exposure on sustained attention ( 3 , 4 , 9 – 13 , 36 ), not all studies have shown positive effects, especially during daytime exposures ( 17 , 37 – 40 ). The inconsistent findings may be due to differences in exposure characteristics including exposure duration and timing, and differences in spectra and intensity between experimental groups.…”

Section: Discussioncontrasting

confidence: 99%

Daytime Exposure to Short Wavelength-Enriched Light Improves Cognitive Performance in Sleep-Restricted College-Aged Adults

et al. 2021

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We tested the effect of daytime indoor light exposure with varying melanopic strength on cognitive performance in college-aged students who maintained an enforced nightly sleep opportunity of 7 h (i.e., nightly sleep duration no longer than 7 h) for 1 week immediately preceding the day of light exposure. Participants (n = 39; mean age ± SD = 24.5 ± 3.2 years; 21 F) were randomized to an 8 h daytime exposure to one of four white light conditions of equal photopic illuminance (~50 lux at eye level in the vertical plane) but different melanopic illuminance [24–45 melanopic-EDI lux (melEDI)] generated by varying correlated color temperatures [3000K (low-melEDI) or 5000K (high-melEDI)] and spectra [conventional or daylight-like]. Accuracy on a 2-min addition task was 5% better in the daylight-like high-melEDI condition (highest melEDI) compared to the conventional low-melEDI condition (lowest melEDI; p < 0.01). Performance speed on the motor sequence learning task was 3.2 times faster (p < 0.05) during the daylight-like high-melEDI condition compared to the conventional low-melEDI. Subjective sleepiness was 1.5 times lower in the conventional high-melEDI condition compared to the conventional low-melEDI condition, but levels were similar between conventional low- and daylight-like high-melEDI conditions. These results demonstrate that exposure to high-melanopic (short wavelength-enriched) white light improves processing speed, working memory, and procedural learning on a motor sequence task in modestly sleep restricted young adults, and have important implications for optimizing lighting conditions in schools, colleges, and other built environments.

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Section: Discussioncontrasting

confidence: 99%

Daytime Exposure to Short Wavelength-Enriched Light Improves Cognitive Performance in Sleep-Restricted College-Aged Adults

et al. 2021

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“…In line with this, the – nonsignificant – difference in sleepiness and vitality between warm vs. cool light was about one fifth of the size of the effect of illuminance. Rather than attributing the alerting effect to illuminance or CCT per se, the melanopic activation that a light setting can achieve is the more likely explanation for this acute, alerting effect (58,59), as was also suggested in the study by Ru et al (31). In this respect, it is important to note that the factor two difference in E D65 v,mel between the warm, bright and the cool, bright light condition did not lead to a difference in sleepiness or vitality, which is possibly due to the nonlinear (sigmoidal) relationship between light and alerting responses (59,60).…”

Section: Discussionmentioning

confidence: 78%

“…This demonstrates that the effects of illuminance and CCT may converge and hence strengthen each other for some measures, but diverge, potentially neutralizing each other for others. Studies investigating the effects of illuminance and CCT simultaneously yet independently are still quite scarce and generally do not focus on the temporal trajectories of the outcome variables in response to the manipulation of one or both of these parameters (26,(28)(29)(30)(31). This stresses the importance to study both light parameters simultaneously and disentangle these two factors.…”

Section: Introductionmentioning

confidence: 99%

Abrupt light transitions in illuminance and CCT result in different temporal dynamics and interindividual variability for sensation, comfort and alertness

Kompier

Smolders

Kort

2020

Preprint

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Detailed insights in both visual effects of light and effects beyond vision due to manipulations in illuminance and correlated color temperature (CCT) are needed to optimize study protocols as well as to design light scenarios for practical applications. This study investigated temporal dynamics and interindividual variability in subjective evaluations of sensation, comfort and mood as well as subjective and objective measures of alertness, arousal and thermoregulation following abrupt transitions in illuminance and CCT in a mild cold environment. The effects could be uniquely attributed to changes in illuminance or CCT and no interaction effects of illuminance and CCT were found for any of these markers. Responses to the abrupt transitions in illuminance and CCT always occurred immediately and exclusively amongst the subjective measures. Most of these responses diminished over time within the 45-minute light manipulation. In this period, no responses were found for objective measures of vigilance, arousal nor thermoregulation. Significant interindividual variability occurred only in the visual comfort evaluation in response to changes in the intensity of the light. The results indicate that the design of dynamic light scenarios aimed to enhance human alertness and vitality requires tailoring to the individual to create visually comfortable environments.

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“…Also, the majority of researches about the effects of light were carried out together with cognitive tasks, e.g. go/no-go, N -back working memory, Psychomotor Vigilance Task, Flanker task, long-term memory, and emotional judgment task 13 , 16 , 17 , 22 , 25 . The tasks performed during light exposure and associated (potential) fatigue might also confound the effects of light on subjective affect and comfort 26 .…”

Section: Introductionmentioning

confidence: 99%

The effects of short-term light exposure on subjective affect and comfort are dependent on the lighting time of day

Chen

Feng

Fan

et al. 2021

Sci Rep

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Light, one of the key environmental components for both life and work, played significant role in subjective feelings (e.g. affect and comfort), but the exact effects and mechanisms were still to be determined. The present study screened thirty healthy adults (13 females, 22.45 ± 3.26 years) and examined subjective affect and comfort under short-term white lights with different combination of correlated color temperature (CCT) and illuminance at different times of day (e.g. morning, afternoon, and evening). Our results showed a significant interaction between illuminance level and time-of-day on subjective comfort. Participants felt more comfortable under 50 lx and 100 lx instead of 500 lx in the evening, and more comfortable under 500 lx in the morning and afternoon. In addition, a positive correlation between illuminance and comfort in the morning and a negative correlation between them in the evening were found. No significant effect of CCT on any subjective feeling was revealed. Our results necessitate the consideration of time-of-day in understanding lighting effects and application of healthy lighting in daily life.

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Non-image forming effects of illuminance and correlated color temperature of office light on alertness, mood, and performance across cognitive domains

Cited by 125 publications

References 79 publications

Daytime Exposure to Short Wavelength-Enriched Light Improves Cognitive Performance in Sleep-Restricted College-Aged Adults

Daytime Exposure to Short Wavelength-Enriched Light Improves Cognitive Performance in Sleep-Restricted College-Aged Adults

Abrupt light transitions in illuminance and CCT result in different temporal dynamics and interindividual variability for sensation, comfort and alertness

The effects of short-term light exposure on subjective affect and comfort are dependent on the lighting time of day

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