Health consequences of electric lighting practices in the modern world: A report on the National Toxicology Program's workshop on shift work at night, artificial light at night, and circadian disruption

Abstract

The invention of electric light has facilitated a society in which people work, sleep, eat, and play at all hours of the 24-hour day. Although electric light clearly has benefited humankind, exposures to electric light, especially light at night (LAN), may disrupt sleep and biological processes controlled by endogenous circadian clocks, potentially resulting in adverse health outcomes. Many of the studies evaluating adverse health effects have been conducted among night- and rotating-shift workers, because this scenario gives rise to significant exposure to LAN. Because of the complexity of this topic, the National Toxicology Program convened an expert panel at a public workshop entitled "Shift Work at Night, Artificial Light at Night, and Circadian Disruption" to obtain input on conducting literature-based health hazard assessments and to identify data gaps and research needs. The Panel suggested describing light both as a direct effector of endogenous circadian clocks and rhythms and as an enabler of additional activities or behaviors that may lead to circadian disruption, such as night-shift work and atypical and inconsistent sleep-wake patterns that can lead to social jet lag. Future studies should more comprehensively characterize and measure the relevant light-related exposures and link these exposures to both time-independent biomarkers of circadian disruption and biomarkers of adverse health outcomes. This information should lead to improvements in human epidemiological and animal or in vitro models, more rigorous health hazard assessments, and intervention strategies to minimize the occurrence of adverse health outcomes due to these exposures.

Circadian phase, circadian period and chronotype are reproducible over months

“…This stable LD cycle may have helped make the DLMOs more stable. Earlier reports suggest that under ecological conditions (outside the laboratory) the correlation between subjective sleep timing and objective circadian timing (DLMO) is rather noisy (Kantermann & Burgess, 2017; Kantermann, 2013; Kantermann et al, 2015; Lunn et al, 2017; Van Reen et al, 2013; Wright et al, 2013). …”

“…Circadian misalignment (sleeping, working, eating, etc. at the wrong phases of the internal circadian clock) results in poor sleep and health and performance decrements (Akerstedt et al, 1984; Archer & Oster, 2015; Gold et al, 1992; Kantermann et al, 2012; Lunn et al, 2017; McHill et al, 2017; Smith & Eastman, 2012). Hence, maintaining the proper alignment between circadian rhythms and the sleep schedule is essential for health and safety.…”

“…In addition, light allows for activities like work or food consumption at the times for natural sleep, which is circadian misalignment and conflicts with a healthy lifestyle (Roenneberg et al, 2012; Wittmann et al, 2006). One prominent example thereof is shift work, which is associated with negative sleep and health outcomes (Akerstedt et al, 1984; Folkard et al, 2005; Gold et al, 1992; Kantermann et al, 2013; Kantermann et al, 2014; Knutsson, 2003; Lunn et al, 2017; Smith & Eastman, 2012). …”

Skyglow changes over Tucson, Arizona, resulting from a municipal LED street lighting conversion

“…A number of known and suspected hazards to wildlife ecology and human health have been identified that are thought to result from exposure to short-wavelength ALAN. [6,7,8] The spectrum shift in new SSL systems is also thought to yield increases to skyglow, which is the diffuse luminescence of the night sky attributable to light emitted from sources on the ground that is scattered back toward the ground from molecules and aerosols in the Earth's atmosphere. Enhanced short-wavelength light emissions associated with blue-rich white LED are subject to strong Rayleigh scattering in the atmosphere, resulting in higher scattering probabilities, associated with the formation of skyglow, than light of longer wavelengths.…”

Reducing the environmental footprint of church lighting: matching façade shape and lowering luminance with the EcoSky LED

“…A great deal of recent work in biology has illuminated the unexpected impacts of light on animal physiology (e.g. [1][2][3]), including that of humans [4]. Light has dramatic effects on animal behavior [5][6][7][8], and is in many cases deadly [9][10][11][12].…”