Psychiatry Investig.  2021 May;18(5):471-477. 10.30773/pi.2020.0348.

Effects of Organic Light-Emitting Diodes on Circadian Rhythm and Sleep

Affiliations
  • 1Department of Neurology, Neuroscience Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
  • 2Department of Neurology, Inje University College of Medicine, Ilsan Paik Hospital, Goyang, Republic of Korea
  • 3Department of Nursing, Samsung Medical Center, Seoul, Republic of Korea
  • 4Department of Clinical Nursing Science, Graduate School of Clinical Nursing Science, Sungkyunkwan University, Seoul, Republic of Korea
  • 5Department of Laboratory Medicine & Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
  • 6Department of Psychiatry, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea

Abstract


Objective
Organic light-emitting diodes (OLEDs) emit less blue light than traditional light-emitting diodes (LEDs), and we previously found that early-night OLED light exposure (LE) delays the melatonin phase by less than LED at a color temperature of 4,000 K. As a follow-up study, we investigated the effects of OLED and LED at a different color temperature (3,000 K) on melatonin profile, sleep, and vigilance.
Methods
24 healthy subjects (27.5±5.1 years) were exposed to three light conditions [OLED, LED, and dim light (DL)] from 17:30 to 24:00, in a random order and with a 1-week interval. Saliva samples for melatonin were taken every hour from 18:00 to 24:00. Polysomnography (PSG) and a psychomotor vigilance test (PVT) were performed.
Results
Melatonin onset time was significantly delayed under OLED and LED compared with DL, with no significant difference between OLED and LED. The mean melatonin level at 24:00 under LED was lower than that under DL, but there was no significant difference between OLED LE and DL. The percentage of slow wave sleep (N3) in LED was significantly lower than in OLED.
Conclusion
Exposure to light in the evening can suppress melatonin secretion late at night and disturb deep sleep, and those effects are slightly worse under LED than OLED.

Keyword

OLED, LED, Light, Melatonin, Sleep
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