Plasma lamps for biological Rhythms (PLACAR) R. Kozakov1, D. Kunz2, C. Stoll2, L. Hitzschke3, J. Meltke4, A. Deitmann5, G. Roth6, H. Rudolph7, K. Barkowsky1, H. Schöpp1 1
INP-Greifswald, F-Hausdorff-Str. 2, Greifswald, D-17489, Germany Charité – University medicine, Sleep Research & Clinical Chronobiology, Gr. Hamburger-Str. 5-11, Berlin, D-10115, Germany 3 OSRAM GmbH, Werner-von-Siemens-Str. 6, 86159 Augsburg, Germany 4 NARVA BEL, Erzstr. 22, 09618 Brand-Erbisdorf, Germany 5 NARVA G.L.E, Herzbergstr. 26, 10365 Berlin, Germany 6 LITEC-LLL, Brandteichstr. 19, 17489 Greifswald, Germany 7 TRILUX GmbH, Heidestr. , 59753 Arnsberg, Germany Contact:
[email protected] 2
ABSTRACT Known effects of light on melatonin suppression were earlier obtained exclusively under strict laboratory conditions. We investigated lamps and fixtures in naturalistic situations. In different common lighting situations melatonin secretion was controlled by saliva samples. The lamps were chosen for good colour rendering index and high efficacy but with different colour temperatures and illuminance values. It was shown that lamps suppress melatonin in different extent depending on their spectral composition. The melatonin suppression can be sufficiently described by a simple model based on its spectral sensitivity curve. TARGET AND INVESTIGATION Investigations in laboratories and usual life situations are often not directly comparable. The project (PLACAR) fills the gap between investigations under strict laboratory conditions and applications in real life situations. It is known that circadian rhythm in humans exists with an increasing melatonin concentration in the evening. It is also known that the melatonin secretion can be influenced by light. Such investigations were carried out with dilated pupils and special lamps. In PLACAR we used commercially available lamps and some modifications of them. We choose fluorescent and HID lamps as well as dielectric barrier discharge lamps. Some of the lamps were modified to achieve lower circadian action.
Fig. 1: Luminance picture of an evening lighting situation in a bathroom with a luminance camera (LMK)
The lamps were characterized in an integrating sphere and optical emission spectroscopy set-ups. Measurements for luminance, illuminance and spectral irradiance for the different lighting situations were carried out with a calibrated luminance camera (LMK), illuminance meter and compact spectrometer in the sleep laboratory. The measuring points were equal to the later positions of the test persons eyes. The illuminance varied between 80 and 500 lx. The lamps and fixtures (bathroom, hall or office) were positioned either in front or above the test persons. An example of an evening lighting situation in a bathroom is given in Fig. 1.
Test persons were in age of 25 to 35 years, healthy, of both sexes and lacked sleep disorders. There were no other restrictions for the choice. They kept constant bed-times and remained in the lab only for the evenings of the test period. No other changes of their normal life were necessary. To ensure reproducibility the tests followed a standardized routine. During the winter period test persons arrived the lab at least several hours before their habitual bed-time and stayed in a dim light situation (
