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.
Copyright © 2012 Elsevier Ltd and The Ergonomics Society. All rights reserved.