Related Experiment Video
Updated: Jul 4, 2026

Blue-hazard-free Candlelight OLED
Published on: March 19, 2017
Effects of short wavelength control in polychromatic light sources on nocturnal melatonin secretion
Tomoaki Kozaki1, Shota Koga, Naohiro Toda
1Faculty of Design, Kyushu University, 4-9-1, Shiobaru, Minami-ku, Fukuoka 815-8540, Japan. kozaki@design.kyushu-u.ac.jp
Abstract:
In this study, 12 healthy males were exposed to various light conditions (2300K, 3000K, 5000K and dim) for 1.5h at midnight. The conditions of 3000K and 5000K were created by commercial fluorescent lamps. The light at 2300K was achieved by fitting a 3000K fluorescent lamp with a special filter that absorbed short-wavelength light. The vertical illuminance level was kept at 200lx. Saliva samples were taken before and after the light exposure. The light at 5000K suppressed melatonin secretion acutely. The 2300K lamp condition appeared to have no effect on melatonin secretion as well as the dim condition, while melatonin secretion was measurably suppressed by the light at 3000K.
Related Concept Videos
Photoreceptors and Visual Pathways
Management of Insomnia
The Pineal Gland
The primary secretion of the pineal gland is the hormone melatonin, derived from serotonin. The concentration of melatonin in the...
Biological Clocks and Seasonal Responses
Circadian Rhythms and Gene Regulation
Chronopharmacokinetics: Circadian Rhythms and Influence on Drug Response
The time of drug administration is an important factor to consider, as it can influence the toxic dose of a drug. For example, a study conducted by Prins et al. in 1997 examined the effects of the timing of...