Blue light from light-emitting diodes elicits a dose-dependent suppression of melatonin in humans

Kathleen E. West, Michael R. Jablonski, Benjamin Warfield, Kate S. Cecil, Mary James, Melissa A. Ayers, James Maida, Charles Bowen, David H. Sliney, Mark D. Rollag, John P. Hanifin, George C. Brainard

Research output: Contribution to journalArticlepeer-review

162 Scopus citations

Abstract

West KE, Jablonski MR, Warfield B, Cecil KS, James M, Ayers MA, Maida J, Bowen C, Sliney DH, Rollag MD, Hanifin JP, Brainard GC. Blue light from light-emitting diodes elicits a dose-dependent suppression of melatonin in humans. J Appl Physiol 110: 619-626, 2011. First published December 16, 2010; doi:10.1152/japplphysiol.01413.2009.-Light suppresses melatonin in humans, with the strongest response occurring in the short-wavelength portion of the spectrum between 446 and 477 nm that appears blue. Blue monochromatic light has also been shown to be more effective than longer-wavelength light for enhancing alertness. Disturbed circadian rhythms and sleep loss have been described as risk factors for astronauts and NASA ground control workers, as well as civilians. Such disturbances can result in impaired alertness and diminished performance. Prior to exposing subjects to short-wavelength light from light-emitting diodes (LEDs) (peak λ = 469 nm; 1/2 peak bandwidth = 26 nm), the ocular safety exposure to the blue LED light was confirmed by an independent hazard analysis using the American Conference of Governmental Industrial Hygienists exposure limits. Subsequently, a fluence-response curve was developed for plasma melatonin suppression in healthy subjects (n = 8; mean age of 23.9 ± 0.5 years) exposed to a range of irradiances of blue LED light. Subjects with freely reactive pupils were exposed to light between 2:00 and 3:30 AM. Blood samples were collected before and after light exposures and quantified for melatonin. The results demonstrate that increasing irradiances of narrowband blue-appearing light can elicit increasing plasma melatonin suppression in healthy subjects (P <0.0001). The data were fit to a sigmoidal fluence-response curve (R2 = 0.99; ED50 = 14.19 μW/cm2). A comparison of mean melatonin suppression with 40 μW/cm2 from 4,000 K broadband white fluorescent light, currently used in most general lighting fixtures, suggests that narrow bandwidth blue LED light may be stronger than 4,000 K white fluorescent light for suppressing melatonin.

Original languageEnglish (US)
Pages (from-to)619-626
Number of pages8
JournalJournal of Applied Physiology
Volume110
Issue number3
DOIs
StatePublished - Mar 1 2011
Externally publishedYes

Keywords

  • Light-emitting diode
  • Pineal

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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