30 noviembre, 2015

How does light affect people, plants and paintings?

The European project HILED ( is probing the effects of light on people’s health and circadian rhythm, the growth rate of plants, and the preservation and perception of paintings. HI-LED is  developing new  light engines by optimising configurations  of  Light Emitting Diodes (LEDs) and by combining LEDs with  Organic Light Emitting Diodes (OLEDs), and creating dynamically tuneable lamps that can fit many different applications. Green OLEDs have been developed which compensate for the low efficiency of green LEDs and are being combined with LEDs in other wavebands to create new  light engines for use in   museum  and human-centric applications.

For human health and performance,  the HI-LED project is considering the effect of different light spectra on the suppression of melatonin (the “sleepiness” hormone), which is a measure for quantifying stimulating of the non-visual pathway, which originates in a special class of  melanopsin-containing retinal cells discovered only in 2002.  The Work has also been performed analysing the potential degradation of artwork by different light spectra.  In addition, an LED light engine has been developed to look at the effects of different light spectra exposure on the growth of horticultural products, e.g. tomatoes, and their effects on leaf area, orientation, plant length as well as photosynthesis and chlorophyll content.

Members of the consortium participated in the annual Vision Sciences Society conference, in Florida in May 2015, featuring a special Pavilion dedicated to the well-known colour-changing Dress. The HI-LED LED light was used to control the specific  light spectra that impinged upon the dress and to recreate the ambiguous lighting conditions which caused different individuals to see the same dress as being different colours.