Effects of Different Light Intensities in the Morning on Dim Light Melatonin Onset

Kozaki, Tomoaki; Toda, Naohiro; Noguchi, Hiroki; Yasukouchi, Akira

doi:10.2114/jpa2.30.97

Cited by 17 publications

(14 citation statements)

References 43 publications

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“…This implication is supported by previous studies showing that high illuminance with blue-enriched light in the morning, as in ECLCP, would cause a greater increase in melatonin secretion at night [10,11]. This may in turn lead to a larger increase and decrease in core body temperature during sleep.…”

Section: Discussionsupporting

confidence: 71%

Optimal Lighting Conditions for Office Workers from the Perspective of Non-visual Effects

Yasukouchi¹,

Toda²,

Noguchi³

2018

KLS

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Optimal lighting conditions for office environments were examined with respect to effects on productivity, alertness, subjective responses, sleep composition, and circadian rhythms of melatonin and body temperature. Participants were 10 healthy male students (mean age: 24.1 ± 1.1). Three lighting conditions were employed: (1) 750 lx and 5000 K, kept constant from 9:00 to 18:00 ( JIS mode); (2) 400 lx and 5000 K, kept constant from 9:00 to 18:00 (SE mode); and (3) 750 lx and 6000 K from 9:00 to 14:00, followed by the eco circadian light control program (ECLCP), in which light intensity and correlated color temperature were gradually lowered to 400 lx and 4000 K from 14:00 to 17:00 and then kept constant until 18:00. Participants stayed in the chamber for approximately 48 h. They performed simulated office tasks from 9:00 to 17:30 with the exception of short breaks for rest and lunch. Simulated office work comprised two parts: (1) performance of the contingent negative variation (CNV) paradigm, and (2) performance of the Cognitive Performance Test of Productivity (CPTOP). Four sequential measurements in each set were employed: (1) subjective evaluation of the environment on a rating scale (3 min), (2) CNV paradigm (15 min), (3) CPTOP (30 min), and (4) rest (15 min). Two sets were carried out in the morning and three sets in the afternoon. Participants were exposed to dim light from 19:30 to 25:00, and saliva samples were taken every 30 min from 20:00 to 25:00 to analyze melatonin concentration. Participants went to bed at 25:30 (< 3 lx) and got up at 7:30. Rectal temperature was recorded during sleep from 25:30 to 7:30. Sleep architecture was also evaluated during this time period on the second night. The experimental conditions on the second day were identical to those on the first day. Data obtained on the second day were used for analysis. Average CNV amplitude in SE mode (400 lx) was significantly smaller than that in JIS mode (750 lx) and ECLCP. The number of errors in the selective response in the CNV paradigm under SE mode was significantly greater than that under JIS mode and ECLCP. The increases and decreases in rectal temperature between bedtime, nadir, and waking time were smallest in SE mode, while the increase was greatest in ECLCP. ECLCP conditions significantly advanced the phase of circadian rhythm and were associated with greater increases in melatonin compared with the JIS and SE conditions before bedtime. Polysomnograms during the first half of sleep tended to show a lower score of stage 3 sleep in SE mode compared with JIS mode and ECLCP, but did not reach the level of significance (p < 0.1).How to cite this article: Akira Yasukouchi, Naohiro Toda, and Hiroki Noguchi, (2018) ICOHS 2017Results indicate that light intensities of less than 400 lx might affect not only alertness and productivity, but also the amplitude and phase of circadian rhythms including sleep composition. Light control conditions such as ECLCP appear to maintain appropriate circadian rhythms while retaining the work ...

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Section: Discussionsupporting

confidence: 71%

Optimal Lighting Conditions for Office Workers from the Perspective of Non-visual Effects

Yasukouchi¹,

Toda²,

Noguchi³

2018

KLS

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“…In the field of physiological anthropology, many studies have shown the effects of light on human physiological functions and health Higuchi et al, 2005;Hirota et al, 2010;Kohyama, 2011;Kozaki et al, 2011). Accumulation of scientific data will enable cultural adaptation, including behavioral and instrumental adaptation, to avoid unfavorable effects of artificial light.…”

Section: Discussionmentioning

confidence: 99%

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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“…It was shown to be effective in some clinical trials and animal models of IBD in ameliorating the condition . Bright light inhibits melatonin secretion . Further detailed examination of the mechanism of colitis including its relation with melatonin suppression by artificial light is necessary.…”

Section: Discussionmentioning

confidence: 99%

“…37,38 Bright light inhibits melatonin secretion. 39 Further detailed examination of the mechanism of colitis including its relation with melatonin suppression by artificial light is necessary. Recent discovery of E4BP4, the transcriptional factor for IL-10, 40 will lead to future exploration of how artificial light affects IL-10-producing cells through mechanisms such as transcription factors.…”

Section: Discussionmentioning

confidence: 99%

Phototherapy with artificial light suppresses dextran sulfate sodium‐induced colitis in a mouse model

Ito

Goto

Oyama

et al. 2014

J of Gastro and Hepatol

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Effects of Different Light Intensities in the Morning on Dim Light Melatonin Onset

Cited by 17 publications

References 43 publications

Optimal Lighting Conditions for Office Workers from the Perspective of Non-visual Effects

Optimal Lighting Conditions for Office Workers from the Perspective of Non-visual Effects

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

Phototherapy with artificial light suppresses dextran sulfate sodium‐induced colitis in a mouse model

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