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Technical environment

Technical environment

Global standard 220V-240V/50Hz-60Hz
Standard for USA/Canada 120V/60Hz, 277V/60Hz
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What is melanopic light effect?

Graphic Circadian rhythm

Change of colour temperature in the course of a (summer) day

The incidence of light in the human eye not only enables visual perception of the surroundings, but also controls the circadian rhythm, the inner clock of people, via the melanopsin-containing ganglion cells in the eye. This correlation was only discovered in 2001.

Melanopic light effect thus means the non-visual, i.e. the controlling effect of light.

Overview of the topic melanopic light effect

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How does the melanopic light effect work?

The melanopsin-containing ganglion cells in the lower back area of the human eye and, to a lesser extent, in other locations below the retina, respond to the blue component in light. With a higher blue component and higher intensity, the resting hormone melatonin is suppressed whilst the level of the activating hormone cortisol increases.

A lower ratio of blue light favours the release of melatonin, which supports falling asleep. The basis of all melanopic light effects is the evolutionary adaptation of humans to the nature of natural daylight and its daily and seasonal changes.

Which factors influence the melanopic light effect?

The essential factors are:

  • The spectral composition of the light – a high ratio of short-wave radiation in the 450-500nm range has a stronger melanopic effect

  • The direction of light incidence (light entering the eye from the upper hemisphere at an angle of 0° to 45° to the horizontal has the greatest effect); for optimum effect, the light source should have the greatest possible spread. With bedridden people it must be taken into account that the direction of view varies depending on the posture or position of the head.

  • Time and duration of exposure to light

  • Age of the target persons

In lighting design, what should be considered regarding the melanopic light effect?

The curve smel(λ) on the left describes the relative spectral sensitivity of the melanopsin-containing photosensitive ganglion cells in the human retina (ipRGC intrinsically photosensitive retinal ganglion cells). The maximum value of sensitivity is at 490nm, approximately in the blue-cyan range of the light spectrum. To make the melanopic lighting effect predictable, the lighting design needs to know the ratio of the melanopically effective component of the illuminance.
The issue of how dependent the effectiveness is on the age of the target persons is also important.

CIE S026 specifies the MDER (Melanopic Daylight Efficacy Ratio) and the MEDI (Melanopic Equivalent Daylight Illuminance) for measuring the melanopic effect. The MDER is the same for all LEDs of a certain type and is specified on the data sheet. The Melanopic Equivalent Daylight Illuminance (MEDI) is obtained by multiplying the visual illuminance (in lux) by the Melanopic Daylight Efficacy Ratio (MDER).

Example: If the visual illuminance is 1000lx and the MDER is 0.468, the MEDI is 1000 x 0.468 = 468lx

Good to know:
The melanopic light effect is especially important in the care sector. People with dementia in particular often lose their day-night rhythm – this can be counteracted by lighting design that takes the melanopic light effect into account.

How high should the melanopically effective illuminance be?

The melanopically effective illuminance should be at least 250lx – values below have no relevant effect. This applies to a 32-year-old person. For older people, the sensitivity to the corresponding wavelengths decreases, as does the pupil aperture. CIE S026 therefore recommends correction factors for older people by which the MEDI is multiplied.

Especially with general lighting, the respective room with its colour scheme and levels of reflection must also be considered. White walls and ceilings are ideal here – red tones, for example, reduce the melanopic light effect.

ERCO Light Knowledge is also available as a whitepaper:

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