Search

Dynamic lighting is a potentially promising solution to meet the individual's chronobiologic and psychological needs at specific times of day or for specific activities. Yet, few studies have investigated the impact of dynamic lighting patterns on daytime functioning and nocturnal sleep, and the optimal dynamic lighting pattern remains largely unknown. The current study assessed the effects of a daylong dynamic lighting (DL) pattern with modulations in intensity and spectrum vs. static office lighting (SL) on markers of well-being, cognitive performance, visual experiences, and sleep in a simulated office environment. Twenty-one subjects participated in the 48-h balanced crossover laboratory study. The findings revealed time-of-day and experimental-day dependent benefits of the DL vs. SL pattern on daytime vitality, sleepiness, state self-control, mood, performance on a sustained attention task and subsequent subjective sleep quality. Complementing earlier research outcomes reported in the literature, the current study suggests that a dynamic lighting approach could be a practical strategy to support office workers' daytime well-being and nocturnal sleep. Yet, the results revealed no consistent pattern across assessments nor across the different types of metrics at a specific assessment, thus additional research regarding the optimization of lighting parameters and pattern is needed.

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 results revealed that effects could be uniquely attributed to changes in illuminance or CCT. 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 or 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.

The use of dynamic light scenarios for indoor environments may be motivated by the aim to support our circadian rhythms or provide a fascinating and/or informative environment. Additionally, dynamic lighting may be beneficial as it could acutely provide support at certain times of day, or for specific tasks or activities. A systematic literature search was performed to explore the dynamic scenarios that have been designed and tested to date. We explored what the motivations behind them were and what the effectiveness of these scenarios was. On all aspects, the fourteen included articles varied substantially. The most promising effect seemed to be improved sleep due to an increased light dose during the day. However, for future work, it is recommended to explicitly explain and carefully align the theoretical rationale, the dynamic light scenario and the study protocol, including outcome measures. This review suggests potential beneficial effects of dynamic light scenarios on human functioning, but also clearly indicates that consolidated strategies for their description and assessment are currently lacking.

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.

Knowledge on the onset, persistence, and symmetry of effects of lighting transitions on humans is relevant when designing dynamic lighting scenarios and, additionally, can shed light on the dominance of underlying mechanisms. We examined temporal trajectories in measures of alertness, arousal and comfort after abrupt lighting transitions that were created using two strongly contrasting light conditions (warm, dim lighting vs. cool, bright lighting). In this controlled within-subjects experiment, thirtyeight healthy subjects participated in four separate sessions of 90 min. Subjective experiences (alertness, comfort and mood) and objective measures of vigilance (PVT performance), arousal (HR, HRV, SCL), and thermoregulation (skin temperature and DPG) were studied. The comparison of the temporal trajectories following the transition in light for the different variables indicates a complex interplay of underlying physiological and psychological processes driving these effects.