Short-wavelength sensitivity for the direct effects of light on alertness, vigilance, and the waking electroencephalogram in humans

To assess the wavelength-dependent sensitivity of the acute effects of ocular light exposure on alertness, performance, waking electroencephalogram (EEG), and cortisol. A between-subjects design was employed to compare the effects of exposure to 460-nm or 555-nm light for 6.5 hours during the biolog...

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Bibliographic Details
Published in:Sleep (New York, N.Y.) Vol. 29; no. 2; p. 161
Main Authors: Lockley, Steven W, Evans, Erin E, Scheer, Frank A J L, Brainard, George C, Czeisler, Charles A, Aeschbach, Daniel
Format: Journal Article
Language:English
Published: United States 01.02.2006
Subjects:
Adult
Arousal - physiology
Disorders of Excessive Somnolence - diagnosis
Disorders of Excessive Somnolence - epidemiology
Electroencephalography
Female
Humans
Hydrocortisone - blood
Male
Melatonin - blood
Photophobia
Psychomotor Performance - physiology
Radioimmunoassay
Sleep Disorders, Circadian Rhythm - blood
Sleep Disorders, Circadian Rhythm - epidemiology
Wakefulness
ISSN:0161-8105
Online Access:Get more information
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Summary:To assess the wavelength-dependent sensitivity of the acute effects of ocular light exposure on alertness, performance, waking electroencephalogram (EEG), and cortisol. A between-subjects design was employed to compare the effects of exposure to 460-nm or 555-nm light for 6.5 hours during the biological night. Intensive Physiological Monitoring Unit, Brigham and Women's Hospital, Boston, MA. Sixteen healthy adults (8 women; mean age +/- SD = 23.3 +/- 2.4 years). Subjects were exposed to equal photon densities (2.8 x 10(13) photons x cm(-2) x s(-1)) of either 460-nm (n = 8) or 555-nm (n = 8) monochromatic light for 6.5 hours, 15 minutes after mydriasis. Subjects underwent continuous EEG/electrooculogram recordings and completed a performance battery every 30 to 60 minutes. As compared with those exposed to 555-nm light, subjects exposed to 460-nm light had significantly lower subjective sleepiness ratings, decreased auditory reaction time, fewer attentional failures, decreased EEG power density in the delta-theta range (0.5-5.5 Hz), and increased EEG power density in the high-alpha range (9.5-10.5 Hz). Light had no direct effect on cortisol. Short-wavelength sensitivity to the acute alerting effects of light indicates that the visual photopic system is not the primary photoreceptor system mediating these responses to light. The frequency-specific changes in the waking EEG indicate that short-wavelength light is a powerful agent that immediately attenuates the negative effects of both homeostatic sleep pressure and the circadian drive for sleep on alertness, performance, and the ability to sustain attention.
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ISSN:0161-8105
DOI:10.1093/sleep/29.2.161