8.4.1 Fading effect. Osram HQI-E 150 W/NDL CL
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has become possible due to additional adaptation of the HCI ® Shoplight, which achieves the best colour rendering properties of all metal halide lamps. Figure 49 shows the values of the colour rendering indices 1 to
14 for four different lamp types with the correlated colour temperature of 3000 K. The advantages can best be seen for colour rendering index R9 for saturated red, but the superiority of POWERBALL ® technology is also apparent for the other colour rendering indices.
reducing the level of melatonin in the bloodstream.
This is called melatonin suppression. (see Fig. 53).
Scientific studies on how light forms or suppresses the sleeping hormone melatonin have shown that together with the visual path which is responsible for vision, there is also a non-visual path which, independent of the visual system, controls melatonin production and therefore the circadian rhythm (daylight rhythm).
8.3 Light and quality of life
It has been a known fact for many years that as well as its known visual effects, light also has other biological effects on the human body. The most acknowledged effect is the way light influences the day-and-night cycle. This influence is also perceived by the eyes, not however via the vision center in the brain but via other nerve cells that affect the pineal gland and hence the forming of the sleep hormone melatonin. Bright light in the night suppresses the formation of melatonin,
While the visual path leads directly from the eye to the vision center of the brain via the optic nerve, the nonvisual path is coupled via the suprachiasmatic nucleus
(SCN) to the pineal gland and controls melatonin production. This process is relatively slow, in time constants of several minutes, while the process of vision takes place within a few 10 ms.
The SCN is a collection of several thousand nerve cells, located above the intersection of the optic nerves (chiasma). This is deemed today to be the main regulator of the inner clock (master clock).
Suprachiasmatic
Nucleus (SCN)
Visual center
Pineal gland
pineal gland
release of
melatonin
50
Ganglion cell in upper cervical vertebra
Spinal cord
Fig. 53: How light affects on the human brain
Retinohypothalamic tract (RHT)
Light
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