Abstract
The dramatic rise in the use of smartphones, tablets, and laptop computers over the past decade has raised concerns about potentially deleterious health effects of increased “screen time” (ST) and associated short-wavelength (blue) light exposure. We determined baseline associations and effects of 6 months’ supplementation with the macular carotenoids (MC) lutein, zeaxanthin, and mesozeaxanthin on the blue-absorbing macular pigment (MP) and measures of sleep quality, visual performance, and physical indicators of excessive ST. Forty-eight healthy young adults with at least 6 h of daily near-field ST exposure participated in this placebo-controlled trial. Visual performance measures included contrast sensitivity, critical flicker fusion, disability glare, and photostress recovery. Physical indicators of excessive screen time and sleep quality were assessed via questionnaire. MP optical density (MPOD) was assessed via heterochromatic flicker photometry. At baseline, MPOD was correlated significantly with all visual performance measures (p < 0.05 for all). MC supplementation (24 mg daily) yielded significant improvement in MPOD, overall sleep quality, headache frequency, eye strain, eye fatigue, and all visual performance measures, versus placebo (p < 0.05 for all). Increased MPOD significantly improves visual performance and, in turn, improves several undesirable physical outcomes associated with excessive ST. The improvement in sleep quality was not directly related to increases in MPOD, and may be due to systemic reduction in oxidative stress and inflammation.
Highlights
Prior to the advent of artificial lighting, the sun was the primary source of light
MP optical density (MPOD) was correlated with photostress recovery (PSR) (r = −0.48; p < 0.001), disability glare (DG) (r = 0.40; p = 0.03), critical flicker fusion frequency (CFF) (r = 0.31; p = 0.035), and Contrast sensitivity (CS) (r = 0.29; p = 0.048)
Several marginal correlations were determined at baseline for the measures of physical indicators of excessive screen time” (ST), including MPOD and eye fatigue (r = −0.26; p = 0.074), eye strain (r = −0.27; p = 0.061), and headache frequency (r = −0.25; p = 0.09)
Summary
Prior to the advent of artificial lighting, the sun was the primary source of light. When the sun sets today, one is hard-pressed to find darkness—illumination from light-emitting diodes (LEDs), and incandescent, fluorescent, and xenon-arc sources (among others) provide indoor and outdoor illumination. The effects of exposure to this seemingly unnatural technological adaptation are starting to become evident, with several studies indicating undesirable associations between exposure to artificial light at night and both reduced sleep quality [1,2] and diminished alertness during the day [3]. American spends 10 h and 39 min viewing screens [5] Such intense use of these devices has been found to have undesirable effects on sleep quality and alertness during waking hours, and on parameters of physical health (e.g., neck and eye strain, eye fatigue, headache; [6,7,8]) and cognitive performance (e.g., poor inhibitory control; [9]). The prevalence of complaints associated with excessive use of computers and other digital devices is so great that the common ocular and physical effects have been collectively termed “Computer Vision Syndrome” (CVS; for a review please see [10])
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