The spectral composition of evening light and individual differences in the suppression of melatonin and delay of sleep in humans

Abstract

The effect of light on circadian rhythms and sleep is mediated by a multi-component photoreceptive system of rods, cones and melanopsin-expressing intrinsically photosensitive retinal ganglion cells. The intensity and spectral sensitivity characteristics of this system are to be fully determined. Whether the intensity and spectral composition of light exposure at home in the evening is such that it delays circadian rhythms and sleep also remains to be established. We monitored light exposure at home during 6-8wk and assessed light effects on sleep and circadian rhythms in the laboratory. Twenty-two women and men (23.1±4.7yr) participated in a six-way, cross-over design using polychromatic light conditions relevant to the light exposure at home, but with reduced, intermediate or enhanced efficacy with respect to the photopic and melanopsin systems. The evening rise of melatonin, sleepiness and EEG-assessed sleep onset varied significantly (P<0.01) across the light conditions, and these effects appeared to be largely mediated by the melanopsin, rather than the photopic system. Moreover, there were individual differences in the sensitivity to the disruptive effect of light on melatonin, which were robust against experimental manipulations (intra-class correlation=0.44). The data show that light at home in the evening affects circadian physiology and imply that the spectral composition of artificial light can be modified to minimize this disruptive effect on sleep and circadian rhythms. These findings have implications for our understanding of the contribution of artificial light exposure to sleep and circadian rhythm disorders such as delayed sleep phase disorder.

Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness

“…In humans, exposure to short-wavelength monochromatic light in the evening has been shown to induce greater circadian and alerting responses than exposure to the same number of photons of longer-wavelength monochromatic light (17)(18)(19)(28)(29)(30)(31)(32)(33)(34), even though the shorter-wavelength light may have a much lower illuminance level when measured in photopic lux (35). For this reason, it has recently been proposed that lux is an inappropriate measure for estimation of the impact of light on melatonin suppression, circadian-phase shifting, and other non-imageforming effects of retinal light exposure (35).…”

Patient-centered lighting environments to improve health care in the intensive care unit

“…But what makes a light source adequate in supporting circadian rhythmicity of a critically ill patient? Experimental data from healthy adults show that besides timing and duration, the effectiveness of light interventions in suppressing melatonin production depends on spectral irradiance, illuminance and luminance of the light source (12)(13)(14)(15)(16).…”

Relationship between Sleep Habits and Daytime Sleepiness, Inattention, and Aggressive Behavior among Taiwanese Kindergarten Children

“…The prefrontal cortex is the primary generator of slow electroencephalogram waveforms and this cerebral region is among the most sensitive to sleep disruption [35]. Exposure to artificial light associated with evening behaviors, such as watching television, has been shown to affect circadian physiology and latent sleep onset [36,37]. The American Academy of Pediatrics and Committee on Public Education identified possible negative health effects of television viewing on children and adolescents, including violent or aggressive behavior, and recommends limiting children's total time spent using electronic media to no more than 1 to 2 hours per day [38].…”