Do no harm: the beginning of the age of healthy hospital lighting

Sleep and circadian disruptors: Unhealthy noise and light levels for hospitalized pediatric patients

Noise and light levels during hospitalizations can disrupt sleep and circadian health, resulting in worsened health outcomes. This study describes patterns of noise and light for inpatient children undergoing stem cell transplants. Objective meters tracked noise and light levels every minute for 6 months. Median overnight sound was 55 dB (equivalent to conversational speech). There were 3.4 loud noises (>80 dB) per night on average. Children spent 62% of the 24-h cycle in nonoptimal lighting, with daytime light dimmer than recommended 98% of the time. Over the 6-month period, the lowest overnight noise level recorded exceeded World Health Organization recommendations for sleep, with frequent spikes into ranges known to cause wakings. During the day, children were rarely exposed to light sufficient to preserve healthy circadian rhythms. Hospitals should address systematic environmental and workflow disruptors to improve the sleep and circadian health of patients, particularly those already at elevated risk for health morbidities.

An efficient LiSrGaF6:Cr3+ fluoride phosphor with broadband NIR emission towards sunlight-like full-spectrum lighting

Sunlight-like full-spectrum phosphor-converted light-emitting diodes (pc-LEDs) require near-infrared (NIR) emission bands to fill the spectrum gap and consequently propel their widespread applications. Although fluoride NIR phosphors have been increasingly investigated, balancing high quantum efficiency (QE), high thermal stability, and wideband NIR emission to obtain excellent overall performance in a single system is still a challenge for Cr3+-doped fluoride NIR phosphor and is significant for direct utilization. Herein, a high-efficiency and thermally stable broadband NIR emission was realized in a novel LiSrGaF6:Cr3+ fluoride phosphor benefitting from a relatively weak crystal field and electron-phonon coupling effect. Upon blue light excitation, the ultra-broad NIR luminescence ranging from 650 to 1150 nm can be achieved with an FWHM of 149 nm peaking at ∼813 nm. Furthermore, this system possesses a high QE of up to 76.88% and its emission intensity at 423 K still maintains 61.62% of its initial intensity at room temperature. An NIR output power of 42.82 mW and photoelectric conversion efficiency of 14.27% of NIR pc-LED devices have also been presented based on this NIR phosphor, demonstrating its possible application in compact nonvisible light sources. In addition, a highly continuous sunlight-like vis-NIR pc-LED was further constructed by employing a blue chip with commercial cyan (BaSi2O2N2:Eu2+), yellow (Y3Al5O12:Ce3+), red (CaAlSiN3:Eu2+), and this LiSrGaF6:Cr3+ NIR phosphor. The as-obtained pc-LED exhibits an ultra-broad spectrum ranging from 400 nm to 1000 nm, exhibiting a higher color reproduction with a color rendering index (CRI) of 95.1 and luminous efficiency (LE) of 50.22 lm W-1. These results indicate that LiSrGaF6:Cr3+ phosphor can be a promising NIR phosphor candidate for high-quality sunlight-like full-spectrum lighting and infrared night vision technology.

Effects of outdoor artificial light at night on human health and behavior: A literature review

The quality of life of human beings has improved tremendously through improved productivity, convenience, safety, and livability due to nighttime lights that illuminate outdoor work, leisure, and mobility. Recently, however, concerns have been growing over outdoor artificial light at night (ALAN) and its effects on human beings as well as ecosystems including animals and plants. This literature review aims to deliver a critical overview of the findings and the areas for future research on the effects of outdoor ALAN on human health and behaviors. Through a narrative literature review, we found that scientific research crucially lacks studies on the effects of outdoor ALAN on human behaviors and health, including social interaction, which may be more widespread compared to what is recognized so far. This review also highlights the importance of investigating the causal and complex relationships between outdoor ALAN, health, and behaviors with sleep as a key mediating factor. We elucidate that outdoor ALAN has both positive and negative effects on human life. Therefore, it is important for societies to be able to access facts and evidence about these effects to plan, agree to, and realize the optimal usage of nighttime lighting that balances its merits and demerits. Researchers in related areas of study must investigate and deliver the science of outdoor ALAN to various stakeholders, such as citizens, policymakers, urban and landscape planners, relevant practitioners, and industries. We believe that our review improves the understanding of outdoor ALAN in relation to human life and contributes to sustainable and thriving societies.