Article

Light level and duration of exposure determine the impact of self-luminous tablets on melatonin suppression

Lighting Research Center, Rensselaer Polytechnic Institute, 21 Union Street, Troy, NY 12180, USA.
Applied ergonomics (Impact Factor: 2.02). 07/2012; 44(2). DOI: 10.1016/j.apergo.2012.07.008
Source: PubMed

ABSTRACT

Exposure to light from self-luminous displays may be linked to increased risk for sleep disorders because these devices emit optical radiation at short wavelengths, close to the peak sensitivity of melatonin suppression. Thirteen participants experienced three experimental conditions in a within-subjects design to investigate the impact of self-luminous tablet displays on nocturnal melatonin suppression: 1) tablets-only set to the highest brightness, 2) tablets viewed through clear-lens goggles equipped with blue light-emitting diodes that provided 40 lux of 470-nm light at the cornea, and 3) tablets viewed through orange-tinted glasses (dark control; optical radiation <525 nm ≈ 0). Melatonin suppressions after 1-h and 2-h exposures to tablets viewed with the blue light were significantly greater than zero. Suppression levels after 1-h exposure to the tablets-only were not statistically different than zero; however, this difference reached significance after 2 h. Based on these results, display manufacturers can determine how their products will affect melatonin levels and use model predictions to tune the spectral power distribution of self-luminous devices to increase or to decrease stimulation to the circadian system.

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    • "Contemporary sleep guidelines dictate that the average adolescent requires between 8.5 and 9.25 h of nocturnal sleep (Carskadon et al. 1980; Matricciani et al. 2013) for optimal health, cognitive, physical, psychological and behavioural outcomes (Auvinen et al. 2010; Matthews et al. 2012; Vriend et al. 2013; Wong, Lau et al. 2013). However, factors, such as a reduced parental influence on bedtime, early waketimes due to schooling commitments and the use of stimulating technological devices prior to bedtime, are all known to lead to the loss of sleep in adolescents (Crowley et al. 2007; Wood et al. 2013). In addition, research on brain maturation indicates a natural increase in daytime sleepiness during adolescence, due to reductions in slow wave sleep and waking brain activity, that is independent of the amount of sleep obtained (Campbell et al. 2007). "
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    • "Many adolescents now use IPADs for reading and game play. Researchers have shown that the blue light from self-luminous tablets can have a negative effect on natural melatonin production and thus disrupt sleep (Wood, Rea, Plitnick, & Figueiro, 2013). "

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    • "In addition, tailored interventions to reduce especially short wavelength (blue) light in the evenings and/or to increase light exposure in the mornings could help to synchronize the students' circadian clocks to their school schedules. The circadian clock is most sensitive to short wavelengths (Brainard et al., 2001), and studies have shown that especially blue light from computers and televisions interferes with sleep and the circadian rhythm (Wood et al., 2013; van der Lely et al., 2014). However, such behavioral interventions are as difficult to achieve on a population level, as are changes in school start times. "
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