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Poster

Circadian Effectiveness of

Ssolar and Artificial Radiation

in Dependence on Age

H. Piazena

, L. Franke

, D. Sülflow

, K. Stark

, D. Kockott

and R. Uebelhack

Klinik für Psychiatrie und Psychotherapie der Charité, Bonhoefferweg 3

D-10117 Berlin

Dr. D. Kockott UV-Technik, Hanau

Abstract

The aim of the investigation was to determine the threshold irradiance of sufficient

melatonin suppression for persons of different age with free pupil adaptation by us-

ing polychromatic radiation with different emission spectra and with different angles

of incidence on the cornea. These data were used to evaluate the circadian effective-

ness of solar irradiance at the Earth´s surface and of different lamp types for chil-

dren, young adults and seniors. Melatonin suppression was measured directly by ana-

lysing blood samples of volunteers classified by their age and exposed by polychro-

matic radiation in dependence on its spectral distribution, on its irradiance and on its

incidence angle on the cornea. Effective threshold irradiances to get saturation of

melatonin suppression were calculated by using the circadian action spectrum. De-

pending on the age, the data ranged between about 0.2 W m

-2

and about 0.6 W m

-2

the case of half spherical geometry and of different emission spectra of white light

lamps. In contrast, decreases of the incident angle resulted in decreases of melatonin

suppression even if the luminance was increased to get equivalent corneal irradiance.

However, the threshold irradiances experimentally determined for persons of differ-

ent age are approximately in line with the thresholds calculated by extrapolation by

using age-dependent spectra of eye transmittance and threshold irradiance data of

melatonin suppression measured in young adults with dilated pupils and with mono-

chromatic radiation. This result is discussed as reference to the applicability of the

additivity law of photobiology to evaluate circadian effectiveness of polychromatic

light sources by weighting with the circadian action spectrum, whereas the experi-

mental data clearly show the violation of the Bunsen-Roscoe law as well as the need to

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Whirlpool EV130 E Instrukcja Użytkownika Strona 323