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Twilight: filter the blue light of your device and sleep better
  1. Arthur Henrique Bossi,
  2. James Hopker
  1. School of Sport and Exercise Sciences, University of Kent, Chatham, Kent, UK
  1. Correspondence to Arthur Henrique Bossi, School of Sport and Exercise Sciences, University of Kent at Medway, Medway Building, Chatham Maritime, Chatham ME4 4AG, Kent, UK; asnb3{at}

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Health and fitness.


Android (V2.2 or above).


Free; ‘Pro’ version available for €1.99/£1.99/US$1.99.

About the app

The Twilight app was created to help people mitigate sleep perturbations arising from the usage of self-illuminating electronic devices (eg, mobile phones and tablets) prior to sleeping.1 Blue light in the range of wavelengths 446–477 nm has been identified as the most potent light stimulus that suppresses melatonin production,2 a hormone that plays a major role in the regulation of sleep and wake cycles.3 Accordingly, Twilight filters the blue light emitted from mobile devices and protects the eyes with a soft red pellicle, potentially helping the user to fall asleep earlier and sleep better.1 ,4 ,5 On the basis of the user's local geographic coordinates, which are taken by …

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  • Twitter Follow Arthur Henrique Bossi at @ahbossi.

  • Funding AHB is a CNPq (Brazillian research funding) scholarship holder. The funder had no role in the study design; in the collection, analysis and interpretation of the data; in the writing of the report; and in the decision to submit the manuscript for publication.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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