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LED-backlit computer screens influence our biological clock and keep us more awake

: Bues, M.; Pross, A.; Stefani, O.; Frey, S.; Anders, D.; Späti, J.; Wirz-Justice, A.; Mager, R.; Cajochen, C.


Journal of the Society for Information Display 20 (2012), Nr.5, S.266-272
ISSN: 1071-0922
Fraunhofer IAO ()

In commodity LC flat-panel displays, the traditional CCFL backlight is being replaced more and more by LEDs. The typical spectrum of LED-lit displays shows a significantly higher amount of blue light in the range around 464 nm. Blue light in this wavelength area suppresses the melatonin level in humans and thus effects the biological clock. Our hypothesis was that the amount of blue light reaching the human eye from a LED-backlit display is sufficient to have a significant effect on the biological clock. The results of clinical user studies comparing the effects of LED- vs. CCFL-backlit displays on humans, resulting from the emitted amount of 464-nm light, will be presented. It was found that the LED-backlit display causes significant suppression of melatonin, which effects the biological clock of the test persons, indicating the necessity for displays with a controllable 464-nm emission. A technical concept for a display with such functionality will be presented.