Nie and colleagues evaluated lighting’s influence on sleep quality and cognitive performance; participants in their study were 18 to 25 years old. The researchers reported that they “optimized and fabricated a four-channel mixed white light with peak wavelengths of 429, 523, 591, and 621 nm. Comparing with common white light emitting diode (LED) (5798 K, 212.7 lx), the mixed white light has lower correlated color temperature (CCT) (2799 K), higher illuminance (356.2 lx), similar melanopic illuminance, and better color fidelity. . . .
Banerjee and associates studied the effect of lighting on visually impaired older individuals’ experiences in their homes. The researchers determined that “better lighting at home was associated with increased physical activity at home. For every 0.1-log units increase in average home lighting, individuals took 5% more daily steps and had a 3% increase in average daily peak cadence. Greater measured lighting was associated with higher physical activity levels in older adults. . . .
The human-generated light that designers choose for spaces has a significant effect on what goes on in our minds and in our bodies. Neuroscience research indicates how to best tune the type of artificial light we experience, that light’s color, intensity, placement, and distribution.
Figueiro and teammates continue their research into circadian lighting. The group reports on data collected at night: “Four ceiling lighting configurations, using combinations of direct and indirect lighting, were implemented along with one design that utilised local lighting. Every design delivered the same high level of circadian-effective lighting to participants. Saliva samples were obtained to measure nocturnal melatonin suppression.
Mangini and colleagues link bed location in a hospital ward to patient sleep. This research team found that “Fifty inpatients were randomized to either CircadianCare . . . or standard of care. . . . Patients in the CircadianCare arm followed 1 of 3 schedules for light/dark, meal, and physical activity timings, based on their diurnal preference/habits. They wore short-wavelength-enriched light-emitting glasses for 45 min after awakening and short-wavelength light filter shades from 18:00 h until sleep onset. . . . there was a trend . . .
New research indicates that nighttime light may affect us in more nuanced ways that previously thought. Blume lead a research team from the University of Basel that reported that “Ambient light however does not only allow us to see, it also influences our sleep-wake rhythm. . . . . If light consists solely of short wavelengths of 440 to 490 nanometres, we perceive it as blue. If short-wavelength light activates the ganglion cells, they signal to the internal clock that it is daytime.
Performance, mental state repercussions
Kwon discusses the implications of the purple LED streetlights appearing worldwide. She reports that “Anecdotal reports of purple-looking streetlights have been popping up. . . . the hue of the light illuminating a roadway could affect how drivers and pedestrians perceive their surroundings as they make their way through the night. And that makes purple streetlights a potential safety hazard. . . . bright purple light suggests the phosphor layer around the lights has been ‘delaminated’—peeled off—exposing the blue LED light underneath. . . .
Henning and associates studied behavior after dark in public spaces lit in different ways. They report that “A field study was conducted to explore user behaviour in two differently illuminated public squares. Observations of the movements and stationary activities of people in the squares were recorded at both squares for the same times of day in the weeks before and after the daylight savings clock change, enabling a comparison of activity in daylight and after dark. 5296 observations were recorded and lighting conditions were captured with HDR-photography and aerial photos.
Engineering "natural" experiences