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Kuhn, L., Johansson, M., Laike, T., & Goven, T. (2013). Residents' perceptions following retrofitting of residential area outdoor lighting with LEDs. Lighting Research and Technology, 45(5), 568–584.
Abstract: The use of light emitting diodes (LEDs) in outdoor lighting has energy-saving potential, but usersâ responses to this light source are largely unknown. An intervention study in two residential areas compared conventional lighting installations (high pressure sodium in Area 1 and high pressure mercury in Area 2) to a retrofitted LED-alternative regarding residentsâ perceptions of quality of light, visual accessibility and danger. Moreover, energy use was calculated. Residentsâ (N = 60) visual accessibility improved and perceived danger remained low in both areas after retrofitting. In Area 2 the perceived quality of light increased, whereas in Area 1 the results were mixed. The retrofitted application reduced energy use by 41â76% and might be a feasible alternative to conventional outdoor lighting in relatively safe areas.
Aubé, M., Roby, J., & Kocifaj, M. (2013). Evaluating potential spectral impacts of various artificial lights on melatonin suppression, photosynthesis, and star visibility. PLoS One, 8(7), e67798.
Abstract: Artificial light at night can be harmful to the environment, and interferes with fauna and flora, star visibility, and human health. To estimate the relative impact of a lighting device, its radiant power, angular photometry and detailed spectral power distribution have to be considered. In this paper we focus on the spectral power distribution. While specific spectral characteristics can be considered harmful during the night, they can be considered advantageous during the day. As an example, while blue-rich Metal Halide lamps can be problematic for human health, star visibility and vegetation photosynthesis during the night, they can be highly appropriate during the day for plant growth and light therapy. In this paper we propose three new indices to characterize lamp spectra. These indices have been designed to allow a quick estimation of the potential impact of a lamp spectrum on melatonin suppression, photosynthesis, and star visibility. We used these new indices to compare various lighting technologies objectively. We also considered the transformation of such indices according to the propagation of light into the atmosphere as a function of distance to the observer. Among other results, we found that low pressure sodium, phosphor-converted amber light emitting diodes (LED) and LED 2700 K lamps filtered with the new Ledtech's Equilib filter showed a lower or equivalent potential impact on melatonin suppression and star visibility in comparison to high pressure sodium lamps. Low pressure sodium, LED 5000 K-filtered and LED 2700 K-filtered lamps had a lower impact on photosynthesis than did high pressure sodium lamps. Finally, we propose these indices as new standards for the lighting industry to be used in characterizing their lighting technologies. We hope that their use will favor the design of new environmentally and health-friendly lighting technologies.
Jou, J. - H., Hsieh, C. - Y., Tseng, J. - R., Peng, S. - H., Jou, Y. - C., Hong, J. H., et al. (2013). Candle Light-Style Organic Light-Emitting Diodes. Adv. Funct. Mater., 23(21), 2750–2757.
Abstract: In response to the call for a physiologically-friendly light at night that shows low color temperature, a candle light-style organic light emitting diode (OLED) is developed with a color temperature as low as 1900 K, a color rendering index (CRI) as high as 93, and an efficacy at least two times that of incandescent bulbs. In addition, the device has a 80% resemblance in luminance spectrum to that of a candle. Most importantly, the sensationally warm candle light-style emission is driven by electricity in lieu of the energy-wasting and greenhouse gas emitting hydrocarbon-burning candles invented 5000 years ago. This candle light-style OLED may serve as a safe measure for illumination at night. Moreover, it has a high color rendering index with a decent efficiency.
Bedrosian, T. A. (Ed.). (2013). Circadian Disruption by Light at Night: Implications for Mood. Ph.D. thesis, , .
Abstract: Life on Earth has adapted to a consistent 24-h solar cycle. Circadian rhythms in physiology and behavior remain synchronized to the environment using light as the most potent entraining cue. During the past century, however, the widespread adoption of electric light has led to `round-the-clockâ societies. Instead of aligning with the environment, individuals follow artificial and often erratic light cycles created by social and work schedules. In particular, exposure to artificial light at night (LAN), termed âlight pollutionâ, has become pervasive over the past 100 years. Virtually every individual living in the U.S. and Europe experiences this aberrant light exposure, and moreover about 20% of the population performs shift work. LAN may disrupt physiological timekeeping, leading to dysregulation of internal processes and misalignment between behavior and the environment. Recent evidence suggests that individuals exposed to excessive LAN, such as night shift workers, have increased risk for depressive disorders, but the biological mechanism remains unspecified. In mammals, intrinsically photosensitive retinal ganglion cells (ipRGCs) project light information to (1) the suprachiasmatic nucleus (SCN) in the hypothalamus, regulating circadian rhythms, and (2) to limbic regions, putatively regulating mood. Thus, LAN has the potential to affect both circadian timekeeping and mood. In this dissertation, I present evidence from rodent studies supporting the novel hypothesis that night-time exposure to light disrupts circadian organization and contributes to depressed mood. First, I consider the physiological and behavioral consequences associated with unnatural exposure to LAN. The effects of LAN on circadian output are considered in terms of locomotor activity, the diurnal cortisol rhythm, and diurnal clock protein expression in the brain in Chapter 2. The influence of LAN on behavior and brain plasticity is discussed, with particular focus on depressive-like behavior (Chapter 3) and effects of SSRI treatment (Chapter 4). Effects of LAN on structural plasticity and gene expression in the brain are described, with emphasis on potential correlates of the depressive-like behavior observed under LAN in Chapter 5. Given the prevalence of LAN exposure and its importance, strategies for reversing the effects are offered. Specifically, eliminating LAN quickly reverses behavioral and physiological effects of exposure as described in Chapter 5. In Chapter 6 I report that administration of a pharmacological cytokine inhibitor prevents depressive-like behaviors in LAN, implicating brain inflammation in the behavioral effect. Finally, I demonstrate in Chapter 7 that exposure to red wavelength LAN reduces the effects on brain and behavior, suggesting that LAN acts through specific retinal pathways involving melanopsin. Taken together, these studies demonstrate the consequences of LAN, but also outline potential avenues for prevention or intervention.
Fuller, G. (Ed.). (2013). The Night Shift: Lighting and Nocturnal Strepsirrhine Care in Zoos. Ph.D. thesis, , .
Abstract: Over billions of years of evolution, light from the sun, moon, and stars has provided
organisms with reliable information about the passage of time. Photic cues entrain
the circadian system, allowing animals to perform behaviors critical for survival and
reproduction at optimal times. Modern artificial lighting has drastically altered
environmental light cues. Evidence is accumulating that exposure to light at night
(particularly blue wavelengths) from computer screens, urban light pollution, or as
an occupational hazard of night-shift work has major implications for human health.
Nocturnal animals are the shift workers of zoos; they are generally housed on
reversed light cycles so that daytime visitors can observe their active behaviors. As a
result, they are exposed to artificial light throughout their subjective night. The goal
of this investigation was to examine critically the care of nocturnal strepsirrhine
primates in North American zoos, focusing on lorises (Loris and Nycticebus spp.) and pottos (Perodicticus potto). The general hypothesis was that exhibit lighting design affects activity patterns and circadian physiology in nocturnal strepsirrhines. The
first specific aim was to assess the status of these populations. A multi-institutional husbandry survey revealed little consensus among zoos in lighting design, with both red and blue light commonly used for nocturnal illumination. A review of medical records also revealed high rates of neonate mortality. The second aim was to
develop methods for measuring the effects of exhibit lighting on behavior and
health. The use of actigraphy for automated activity monitoring was explored.
Methods were also developed for measuring salivary melatonin and cortisol as
indicators of circadian disruption. Finally, a multi-institutional study was conducted
comparing behavioral and endocrine responses to red and blue dark phase lighting.
These results showed greater activity levels in strepsirrhines housed under red light than blue. Salivary melatonin concentrations in pottos suggested that blue light
suppressed nocturnal melatonin production at higher intensities, but evidence for
circadian disruption was equivocal. These results add to the growing body of
evidence on the detrimental effects of blue light at night and are a step towards
empirical recommendations for nocturnal lighting design in zoos.