New metrics for circadian light stimulus
In the Eindhoven ecosystem I just found out about an important research from M. Figueiro et all in 2011, released in Sept. 2015 named Modeling the spectral sensitivity of the human circadian system.
Interestingly its seems not only are our ganglion-cells are contributing to melatonine suppression (via our nerve system, the biological clock, and the pineal gland) during the day, also our cones and rods are in play. Therefore a new formula takes into account the effects regarding cones and rods sensitivity, amongst others the blue-yellow crosspoint at around 507 Nm.
This results in a new updated and hopefully more accurate way of knowing certain light is beneficial to our health regarding 'giving us the right proportion of daylight' preferably at the right time (of day and season).
The new formula to calculate so called Circadian Stimulus (CS) is available online: http://www.lrc.rpi.edu/cscalculator/
and our Sparckel performs as seen below. It is said the a CS below 0.1 has no effect on melatonine suppression. A CS of 0.3 has effect. And a CS score 0.5 has great effect.
Our Sparckel light is measured vertically next to the human eye. With a regular positioning on a working desk Sparckel creates 800 lux easily giving a CS value of 0.506.
According to this new formula Sparckel is substantially effective regarding melatonin suppression during daytime.