Inter-individual difference in pupil size correlates to suppression of melatonin by exposure to light

Higuchi, Shigekazu; Ishibashi, Keiichiro; Aritake, Sayaka; Enomoto, Minori; Hida, Akiko; Tamura, Miyuki; Kozaki, Tomoaki; Motohashi, Yutaka; Mishima, Kazuo

doi:10.1016/j.neulet.2008.05.037

Cited by 42 publications

(37 citation statements)

References 31 publications

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“…The results of the present study suggested that response to mRGCs was lower in the red visor condition than in the blue visor condition. It has been shown that dilated or large pupils increase light-induced melatonin suppression (Gaddy et al, 1993;Higuchi et al, 2008). In the present study, the constriction of pupils in the blue visor condition may have weakened the melatonin suppression by light.…”

Section: Discussionmentioning

confidence: 42%

Effectiveness of a Red-visor Cap for Preventing Light-induced Melatonin Suppression during Simulated Night Work

Higuchi

Fukuda

Kozaki

et al. 2011

J Physiol Anthropol

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Bright light at night improves the alertness of night workers. Melatonin suppression induced by light at night is, however, reported to be a possible risk factor for breast cancer. Short-wavelength light has a strong impact on melatonin suppression. A red-visor cap can cut the short-wavelength light from the upper visual field selectively with no adverse effects on visibility. The purpose of this study was to investigate the effects of a red-visor cap on light-induced melatonin suppression, performance, and sleepiness at night. Eleven healthy young male adults (mean age: 21.2Ϯ0.9 yr) volunteered to participate in this study. On the first day, the subjects spent time in dim light (Ͻ15 lx) from 20:00 to 03:00 to measure baseline data of nocturnal salivary melatonin concentration. On the second day, the subjects were exposed to light for four hours from 23:00 to 03:00 with a nonvisor cap (500 lx), red-visor cap (approx. 160 lx) and blue-visor cap (approx. 160 lx). Subjective sleepiness and performance of a psychomotor vigilance task (PVT) were also measured on the second day. Compared to salivary melatonin concentration under dim light, the decrease in melatonin concentration was significant in a nonvisor cap condition but was not significant in a red-visor cap condition. The percentages of melatonin suppression in the nonvisor cap and red-visor cap conditions at 4 hours after exposure to light were 52.6Ϯ22.4% and 7.7Ϯ3.3%, respectively. The red-visor cap had no adverse effect on performance of the PVT, brightness and visual comfort, though it tended to increase subjective sleepiness. These results suggest that a red-visor cap is effective in preventing melatonin suppression with no adverse effects on vigilance performance, brightness and visibility.

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Section: Discussionmentioning

confidence: 42%

Effectiveness of a Red-visor Cap for Preventing Light-induced Melatonin Suppression during Simulated Night Work

Higuchi

Fukuda

Kozaki

et al. 2011

J Physiol Anthropol

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“…Some melanopsin-containing cells send branched projections to the pretectal area and the master circadian clock in the suprachiasmatic nucleus50, but there are also distinct subpopulations of ipRGCs that project to these brain sites51. Although these pathways could be differentially affected in aging, pupil size measured during exposure to light has been shown to correlate with the magnitude of melatonin suppression in humans52. Additionally, the amplitude of the PIPR after exposure to blue light has been shown to correlate with the midpoint of nocturnal sleep under free-living conditions, which is often used as an estimate of circadian timing53.…”

Section: Discussionmentioning

confidence: 99%

Pupillary responses to short-wavelength light are preserved in aging

Rukmini

Miléa

Aung

et al. 2017

Sci Rep

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With aging, less blue light reaches the retina due to gradual yellowing of the lens. This could result in reduced activation of blue light-sensitive melanopsin-containing retinal ganglion cells, which mediate non-visual light responses (e.g., the pupillary light reflex, melatonin suppression, and circadian resetting). Herein, we tested the hypothesis that older individuals show greater impairment of pupillary responses to blue light relative to red light. Dose-response curves for pupillary constriction to 469-nm blue light and 631-nm red light were compared between young normal adults aged 21–30 years (n = 60) and older adults aged ≥50 years (normal, n = 54; mild cataract, n = 107; severe cataract, n = 18). Irrespective of wavelength, pupillary responses were reduced in older individuals and further attenuated by severe, but not mild, cataract. The reduction in pupillary responses was comparable in response to blue light and red light, suggesting that lens yellowing did not selectively reduce melanopsin-dependent light responses. Compensatory mechanisms likely occur in aging that ensure relative constancy of pupillary responses to blue light despite changes in lens transmission.

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“…There are interindividual variations in melatonin suppression by light (7,8). These variations may be important when estimating the effects of light at night.…”

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confidence: 99%