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User-defined programmable daily colour-cycles for complementary lighting

·         Variations in the colour of light for use as a marker of the passage of time

·         The spectral values which characterise circadian sensitivity differ from those for vision; the daily cycle of change is based on the circadian colour range

·         Creates a changing atmosphere throughout the daily cycle

·         Complements existing light sources (natural or artificial)

·         Configured to the users daily and working schedule and specific needs

·         Designed to act against monotony,  visual fatigue, contrast and associated glare

·         May be implemented in the form of mural lighting, backlit panels, artificial skylights and windows, with or without graphics

·         Simple programming via a CE-compliant dedicated controller which may be wall-mounted, built into a panel, or mounted on the electricity board

·         One-time programming for year-round use including progressive summer-winter hour-changes



Colour variations using LED sources - photos : LDI 


Why biocentric? Because lighting in today's world has to be adapted to the user, and not the other way around. Anybody who has lived or worked in a constantly artificially-lit environment will know the disorientation which results from the absence of natural light as a "time-giver".

To this end we have designed what we believe is the most perfected system available to provide vibrant colour-variations for use as complementary lighting throughout the user's day. 

The efficiency of colours in resetting circadian  timing differ substantially from their visual efficiency. Our approach exploits this feature to provide complementary lighting (additional to functional lighting which is white or near-white).

The colour-cycles keep to sinusoidal shapes which characterise daily light in the natural conditions in which humans have evolved.

 The shape of the daily colour-pattern may be modified for specific users requiring an advance or delay in their daily circadian cycle.


Key principles


Biocentric lighting is, by definition, lighting that is centred on the organism. It promotes health and well-being. One of the features of most contemporary lighting systems is their constancy, which is a source of discomfort to many people subjected environments in which static artificial lighting is predominant.


Recent years have brought advances in the form of “dynamic” lighting which varies the main lighting system from “warm” to “cool” white (the colour temperature) across the day according to a standard program.  Biocentric lighting, by contrast, aims to provide visible time-givers in the form of complementary lighting. It makes use of colour functions derived from the response of the human circadian system to different parts of the visible spectrum, and translates these functions into sinusoids which can be stretched over the user’s waking day.


The program we have developed is user-specific, which means that the shape of the sinusoid can be modified according to the needs of individual users. The apex or mid-day can be shifted in relation to user needs. User needs are dictated typically by lifestyle, work-schedules, state of health, and age, and the needs of any single individual may vary from others according to any of these factors.



Mural colour cycle

Morning                         Mid-day                         Evening

 Skylight colour cycle


Morning                         Mid-day                         Evening



Daily colour cycles for mural and skylight applications



User options:


  • Option of daily schedule (waking day)
  • Option daily centre-point (mid-day)
  • Option of the shape of the cycle
  • Option of level of colour saturation
  • Option of the number of channels (several varied colour channels are calculated  around a mean circadian efficiency value for the colours combined)
  • Option of colour value-adjustment for different makes of RGB appliances
  • May be used with FTs (wall-wash applications)
  • Option of gradual daily-cycle shift between winter- and summer-time changes


For further information:




conditions d'acces        conditions of use
updated November 2011    B-4420 Liège - Belgium   copyright  Véronique Claeys Ing.  (c) 2003-2011