Wenye Hu

Light interventions have been investigated for treating sleep disturbances in older adults; however, findings are mixed. This proof‐of‐concept trial investigated the effect of blue‐enriched ambient light on electroencephalographic (EEG) sleep in older adults with self‐reported poor sleep. Twelve participants (65.6 ± 8.7 years) were randomly exposed to two 72‐h in‐laboratory light conditions separated by 2 weeks. During the day, participants were exposed to either blue‐enriched light (intervention: melanopic equivalent daylight illuminance (EDI) = 843.6 lx) or standard light (control: melanopic EDI = 215.8 lx). Three hours before habitual bedtime, illuminance was reduced, with greater blue light attenuation in the intervention (melanopic EDI = 49.5 lx) than control (melanopic EDI = 60.8 lx). On the third night, high‐density EEG sleep, cognitive performance and body temperature were assessed. The primary outcome was wake‐after‐sleep‐onset (WASO). Secondary outcomes included polysomnography‐derived sleep parameters, sleep spindles, cognitive performance and body temperature. High‐density EEG spectral power analyses were exploratory. There was no significant difference in WASO (136.1 ± 52.6 min vs. 117.2 ± 43.9 min; p = 0.338) between intervention and control. Intervention light significantly increased sigma activity (12–16 Hz) during N1 ( p = 0.010) and N2 ( p = 0.017) sleep. The distal‐proximal skin temperature gradient (surrogate of peripheral heat dissipation) before and after lights out increased under intervention compared to control (−1.21°C ± 1.44°C vs. −1.85°C ± 1.39°C, p < 0.001). Daytime enrichment and evening depletion of blue light did not improve objective sleep outcomes in older people with sleep disturbance, but exploratory analyses showed increased sigma activity during sleep. Lighting interventions to improve sleep in older populations require further investigation. Trial Registration: ACTRN12619000138189

Sports hall buildings are widely utilized as fitness facilities where the occupants can engage in physical activities to promote their health and well-being. Lighting system within the sports hall buildings must therefore meet several requirements, including those for the emerging non-visual lighting metrics, in support of the health and well-being requirement. Inaccurate prediction of non-visual lighting metrics in such spaces can lead to suboptimal lighting design, potentially affecting the performance and overall experience. Existing validation studies in the literature mostly focused on office buildings, which have fundamentally different characteristics compared to sports facilities. This research thus focuses on the assessment of accuracy of multispectral lighting simulation workflows for the scenarios of electric lighting in sports halls. Field measurements of vertical illuminance and spectral irradiance were conducted at five badminton courts in a sports hall, which were compared with simulations using Lark. Calibration was conducted by adjusting the lower-bound wavelength values and applying calibration factors to each spectral channel in Lark. After calibration, the percentage error of vertical illuminance was reduced to an acceptable level of -0.4% to +1.5%. Overall, this study highlights the importance of incorporating accurate simulation input and calibrated multispectral tools in sports hall lighting design.

Traditional photometric measures fail to accurately estimate perceived brightness, leading to the development of spatial brightness as a concept to quantify overall scene brightness. Recent research has revealed that melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs), in addition to cone cells, contributes to brightness perception, and new metrics have been developed to predict cone and melanopsin-driven brightness perception. This study evaluates the performance of three melanopsin-based spatial brightness metrics through a two-alternative forced choice (2AFC) simultaneous brightness experiment involving 15 pairs of lighting conditions. Results indicate that the melanopsin-based spatial brightness metrics perform poorly, with a maximum accuracy of 50%, which is on par with chance. Future research should explore a wider range of illuminance, melanopic illuminance, and correlated colour temperatures (CCT) levels.

Exposure to light is an important factor in regulating sleep and sleep quality, especially for elderly people with a high risk of sleep problems. A systematic literature review was conducted to explore the current understanding of the relationship between light and sleep quality of the elderly, and to identify methodological gaps and soundness of existing studies to inform the design of future experimental studies. Specific focus is given to healthcare centres and similar settings due to their controlled environment and the high prevalence of sleep disturbances. Out of 406 publications screened from four databases—namely Google Scholar, Semantic Scholar, Lens.Org, and Scopus—380 studies remained after removing duplicates, and 19 studies published after 2002 that were relevant to the review topic were selected based on the PRISMA 2020 guidelines. The selected studies were analysed using six key aspects, which reflect typical components of experimental design such as participants’ characteristics, experiment and exposure duration, mode of light exposure, lighting and light interventions, experiment procedure, and data collection methods. The results indicated that many studies have limitations in terms of the accuracy and generalisability of findings in representing the entire elderly population due to issues with experimental design or control of the participants’ attendance. The results suggest that future studies should increase the duration of light intervention to around 21–35 days and the number of participants to around 14 and 47. The issues identified from the experimental designs of the selected studies provide valuable insights for establishing guidelines and recommendations for future studies.