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Type: Journal article
Title: Differential effects of light wavelength in phase advancing the melatonin rhythm
Author: Wright, H.
Lack, L.
Kennaway, D.
Citation: Journal of Pineal Research, 2004; 36(2):140-144
Publisher: Blackwell Munksgaard
Issue Date: 2004
ISSN: 0742-3098
Statement of
Helen R. Wright, Leon C. Lack and David J. Kennaway
Abstract: Shorter wavelength light has been shown to be more effective than longer wavelengths in suppressing nocturnal melatonin and phase delaying the melatonin rhythm. In the present study, different wavelengths of light were evaluated for their capacity to phase advance the saliva melatonin rhythm. Two long wavelengths, 595 nm (amber) and 660 nm (red) and three shorter wavelengths, 470 nm (blue), 497 nm (blue/green), and 525 nm (green) were compared with a no-light control condition. Light was administered via a portable light source comprising two light-emitting diodes per eye, with the irradiance of each diode set at 65 μW/cm2. Forty-two volunteers participated in up to six conditions resulting in 15 per condition. For the active light conditions, a 2-hr light pulse was administered from 06:00 hr on two consecutive mornings. Half-hourly saliva samples were collected on the evening prior to the first light pulse and the evening following the second light pulse. The time of melatonin onset was calculated for each night and the difference was calculated as a measure of phase advance. The shorter wavelengths of 470, 495 and 525 nm showed the greatest melatonin onset advances ranging from approximately 40–65 min while the longer wavelengths produced no significant phase advance. These results strengthen earlier findings that the human circadian system is more sensitive to the short wavelengths of light than the longer wavelengths.
Keywords: Saliva
Circadian Rhythm
Dose-Response Relationship, Drug
Time Factors
Description: The definitive version is available at
DOI: 10.1046/j.1600-079X.2003.00108.x
Appears in Collections:Aurora harvest
Obstetrics and Gynaecology publications

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