Shedding Some Light on Night Shift in iOS 9.3

Given that cognitive productivity is influenced by the brain’s circadian mechanisms, and that information technology and other technology can interfere with these mechanisms, you might be interested in a recent blog post of mine on The post is a response to the introduction of a Blue Light Reduction setting in the Display & Brightness panel of iOS 9.3.

In 1998, it was discovered that there are blue light receptors in the retina whose purpose is to inform the brain’s circadian mechanisms, including the hormone, melatonin, and the suprachiasmatic nucleus (in the hypothalamus). Light can delay and lessen melatonin levels, increasing sleep onset latency and possibly having other deleterious effects.

Many people are increasingly concerned about the effects on sleep of blue light emitted by their devices particularly since the following publication made headlines last year:

Chang, A.-M., Aeschbach, D., Duffy, J. F., & Czeisler, C. A. (2015). Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. Proceedings of the National Academy of Sciences, 112(4), 1232–1237.

My position, in short, is that the night shift feature seems to be a step in the right direction. However,

  • Blue light is emitted from many other sources than smartphones and tablets, not all of which are yet easy to control (e.g., TV).
  • Some sleep researchers have started to wear blue-light filtering glasses when using IT before bed.
  • iOS 9.3 is probably only the beginning of the beginning of using IT to control the light spectrum.
  • In particular, given all the R&D on “smart homes”, I can envision a future in which people can control the light emanating from all their devices (including artificial lights).

For a bit more on all this, see my recent blog post, and some of the references it provides.

Published by

Luc P. Beaudoin

Head of CogZest. Author of Cognitive Productivity books. Co-founder of CogSci Apps Corp. Adjunct Professor of Education, Simon Fraser University. Why, Where, and What I Write. See About Me for more information.

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