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Shigekazu HIGUCHI Last modified date:2024.04.30

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Field of Specialization
Physiological Anthropology, Ergonomics, Sleep and Circadian rhythm, Neuroscience, Knasei Science
ORCID(Open Researcher and Contributor ID)
Research Interests
  • A study of individual and ethnic differences in light sensitivity of circadian rhythms
    keyword : circadian rhythm, individual differences, ethnic differences, light sensitivity
  • Study on light and circadian rhythm in chldren
    keyword : Children, Sleep, Circadian rhythm, melatonin, lighting environment
  • Study on the effects of light on circadian rhythm and melatonin during night work
    keyword : night work, light, circadian rhythm, melatonin, performance, sleepiness
  • Study on human mirror neuron system
    keyword : neuroscience, mirror neuron system
Academic Activities
1. Nicholas Mascie-taylor(編集), Akira Yasukouchi(編集), Stanley Ulijaszek(編集), Human Variation: From the Laboratory to the Field, Crc Pr I Llc, 「Human adaptation to natural and artificial light -variation in circadian photosensitivity –」(pp69-84)を担当, 2010.03.
1. Ohashi, Michihiro, Taisuke Eto, Toaki Takasu, Yuki Motomura, Shigekazu Higuchi, Relationship between Circadian Phase Delay without Morning Light and Phase Advance by Bright Light Exposure the Following Morning, Clocks & Sleep, 10.3390/clockssleep5040041, 5, 4, 615-626, 2023.10.
2. Taisuke Eto, Shigekazu Higuchi, Review on age-related differences in non-visual effects of light: melatonin suppression, circadian phase shift and pupillary light reflex in children to older adults, Journal of Physiological Anthropology, 10.1186/s40101-023-00328-1, 42, 1, 2023.06.
3. Taisuke Eto, Shingo Kitamura, Kana Nishimura, Kota Takeoka, Yuki Nishimura, Sang-il Lee, Michihiro Ohashi, Akiko Shikano, Shingo Noi, Shigekazu Higuchi, Circadian phase advances in children during camping life according to the natural light-dark cycle, Journal of Physiological Anthropology, 10.1186/s40101-022-00316-x, 41, 1, 2022.12.
4. Michihiro Ohashi, Sang-il Lee, Taisuke Eto, Nobuo Uotsu, Chie Tarumizu, Sayuri Matsuoka, Shinobu Yasuo, Shigekazu Higuchi, Intake of l-serine before bedtime prevents the delay of the circadian phase in real life, Journal of Physiological Anthropology, 10.1186/s40101-022-00306-z, 41, 1, 2022.08, Background
It has been shown in laboratory experiments using human subjects that ingestion of the non-essential amino acid L-serine before bedtime enhances the advance of circadian phase induced by light exposure the next morning. In the present study, we tested the effect of ingestion of L-serine before bedtime on circadian phase in real life and whether its effect depends on the initial circadian phase.
The subjects were 33 healthy male and female university students and they were divided into an L-serine group (n = 16) and a placebo group (n = 17). This study was conducted in a double-blind manner in autumn and winter. After a baseline period for 1 week, the subjects took 3.0 g of L-serine or a placebo 30 min before bedtime for 2 weeks. Saliva was collected twice a week at home every hour under a dim light condition from 20:00 to 1 h after habitual bedtime. Dim light melatonin onset (DLMO) was used as an index of phase of the circadian rhythm.
DLMO after intervention was significantly delayed compared to the baseline DLMO in the placebo group (p = 0.02) but not in the L-serine group. There was a significant difference in the amount of changes in DLMO between the two groups (p = 0.04). There were no significant changes in sleeping habits after intervention in the two groups. There were significant positive correlations between advance of DLMO and DLMO before intervention in the L-serine group (r = 0.53, p Conclusions
Our findings suggest that intake of L-serine before bedtime for multiple days might attenuate the circadian phase delay in the real world and that this effect does not depend on the initial circadian phase..
5. Shigekazu Higuchi, Yandan Lin, Jingjing Qiu, Yichi Zhang, Michihiro Ohashi, Sang-il Lee, Shingo Kitamura, Akira Yasukouchi, Is the use of high correlated color temperature light at night related to delay of sleep timing in university students? A cross-country study in Japan and China, Journal of Physiological Anthropology, 10.1186/s40101-021-00257-x, 40, 1, 7-7, 2021.12, Abstract
Blue-enriched white light at night has the potential to delay the circadian rhythm in daily life. This study was conducted to determine whether the use of high correlated color temperature (CCT) light at home at night is associated with delay of sleep timing in university students.

The survey was conducted in 2014–2015 in 447 university students in Japan and 327 students in China. Habitual sleep timing and type of CCT light at home were investigated by using a self-administered questionnaire. The Japanese students were significantly later than the Chinese students in bedtime, wake time, and midpoint of sleep. They were asked whether the lighting in the room where they spend most of their time at night was closer to warm color (low CCT) or daylight color (high CCT). The amount of light exposure level during daily life was measured for at least 1 week by the use of a light sensor in 60 students in each country.

The percentages of participants who used high CCT lighting at night were 61.6% for Japanese students and 80.8% for Chinese students. Bedtime and sleep onset time on school days and free days were significantly later in the high CCT group than in the low CCT group in Japan. The midpoint of sleep in the high CCT group was significantly later than that in the low CCT group on free days but not on school days. On the other hand, none of the sleep measurements on school days and free days were significantly different between the high CCT and low CCT groups in China. Illuminance level of light exposure during the night was significantly higher in Japanese than in Chinese, but that in the morning was significantly higher in China than in Japan.

The use of high CCT light at night is associated with delay of sleep timing in Japanese university students but not in Chinese university students. The effects of light at night on sleep timing and circadian rhythm may be complicated by other lifestyle factors depending on the country.

6. Taisuke Eto, Michihiro Ohashi, Kotaro Nagata, Nakyeong Shin, Yuki Motomura, Shigekazu Higuchi, Crystalline lens transmittance spectra and pupil sizes as factors affecting light-induced melatonin suppression in children and adults, OPHTHALMIC AND PHYSIOLOGICAL OPTICS, 10.1111/opo.12809, 2021.07.
7. Eto T,Petteri Teikari,Raymond P. Najjar,Nishimura Y,Motomura Y,Kuze M Higuchi S, A Purkinje image-based system for an assessment of the density and transmittance spectra of the human crystalline lens in vivo, scientific reports, 10.1038/s41598-020-73541-y, 2020.10, A method for rapid and objective assessment of ocular lens density and transmittance is needed for research and clinical practice. The aim of this study was to determine whether the Purkinje image-based technique can be used for objective and accurate quantification of spectral density and transmittance of ocular media (the mainly crystalline lens) in visible light. Twenty-six individuals (10 young, 9 middle-aged and 7 older individuals) participated in this study. Spectral lens density was evaluated by detecting the intensity of the IVth Purkinje image for different wavelengths. Subsequently, optical density index (ODI), the area under the curve in the lens density spectrum, was calculated and ODIs were compared with clinical lens opacification scales assessed subjectively using a slit lamp. Spectral lens transmittance was estimated from the lens density spectrum. Lens densities were higher in the short wavelength region of the visible spectrum across all age groups. ODI was highly correlated with the clinical opacification scale, while lens transmittance decreased with aging. Our results showed that spectral transmittance of the human crystalline lens can be easily estimated from optical density spectra evaluated objectively and rapidly using the Purkinje image-based technique. Our results provide clinicians and scientists with an accurate, rapid and objective technique for quantification of lens transmittance..
8. Sang‐il Lee,Kouhei Matsumori,Kana Nishimura,Yuki Nishimura,Yuki Ikeda,Taisuke Eto,Shigekazu Higuchi, Melatonin suppression and sleepiness in children exposed to blue‐enriched white LED lighting at night, Physiological Reports, 2018.12, Light‐induced melatonin suppression in children is reported to be more sensitive to white light at night than that in adults; however, it is unclear whether it depends on spectral distribution of lighting. In this study, we investigated the effects of different color temperatures of LED lighting on children's melatonin secretion during the night. Twenty‐two healthy children (8.9 ± 2.2 years old) and 20 adults (41.7 ± 4.4 years old) participated in this study. A between‐subjects design with four combinations, including two age groups (adults and children) and the two color temperature conditions (3000 K and 6200 K), was used. The experiment was conducted for two consecutive nights. On the first night, saliva samples were collected every hour under a dim light condition (
9. Shinobu Yasuo, Ayaka Iwamoto, Sang Il Lee, Shotaro Ochiai, Rina Hitachi, Satomi Shibata, Nobuo Uotsu, Chie Tarumizu, Sayuri Matsuoka, Mitsuhiro Furuse, Shigekazu Higuchi, L-serine enhances light-induced circadian phase resetting in mice and humans, Journal of Nutrition, 10.3945/jn.117.255380, 147, 12, 2347-2355, 2017.12, Background: The circadian clock is modulated by the timing of ingestion or food composition, but the effects of specific nutrients are poorly understood. Objective: We aimed to identify the amino acids that modulate the circadian clock and reset the light-induced circadian phase in mice and humans. Methods: Male CBA/N mice were orally administered 1 of 20 L-amino acids, and the circadian and light-induced phase shifts of wheel-running activity were analyzed. Antagonists of several neurotransmitter pathways were injected before L-serine administration, and light-induced phase shifts were analyzed. In addition, the effect of L-serine on the light-induced phase advance was investigated in healthy male students (mean ± SD age 22.2 ± 1.8 y) by using dim-light melatonin onset (DLMO) determined by saliva samples as an index of the circadian phase. Results: L-Serine administration enhanced light-induced phase shifts inmice (1.86-fold; P
10. Tokiho Akiyama, Takafumi Katsumura, Shigeki Nakagome, Sang Il Lee, Keiichiro Joh, Hidenobu Soejima, Kazuma Fujimoto, Ryosuke Kimura, Hajime Ishida, Tsunehiko Hanihara, Akira Yasukouchi, Yoko Satta, Shigekazu Higuchi, Hiroki Oota, An ancestral haplotype of the human PERIOD2 gene associates with reduced sensitivity to light-induced melatonin suppression, PLoS One, 10.1371/journal.pone.0178373, 12, 6, 2017.06, Humans show various responses to the environmental stimulus in individual levels as physiological variations. However, it has been unclear if these are caused by genetic variations. In this study, we examined the association between the physiological variation of response to light-stimulus and genetic polymorphisms. We collected physiological data from 43 subjects, including light-induced melatonin suppression, and performed haplotype analyses on the clock genes, PER2 and PER3, exhibiting geographical differentiation of allele frequencies. Among the haplotypes of PER3, no significant difference in light sensitivity was found. However, three common haplotypes of PER2 accounted for more than 96% of the chromosomes in subjects, and 1 of those 3 had a significantly low-sensitive response to light-stimulus (P
11. Kazuo Isoda, Kana Sueyoshi, Yuki Ikeda, Yuki Nishimura, Ichiro Hisanaga, Stéphanie Orlic, Yeon Kyu Kim, Shigekazu Higuchi, Effect of the hand-omitted tool motion on mu rhythm suppression, Frontiers in Human Neuroscience, 10.3389/fnhum.2016.00266, 10, 2016.06, In the present study, we investigated the effect of the image of hands on mu rhythm suppression invoked by the observation of a series of tool-based actions in a goal-directed activity. The participants were 11 university students. As a source of visual stimuli to be used in the test, a video animation of the porcelain making process for museums was used. In order to elucidate the effect of hand imagery, the image of hands was omitted from the original (“hand image included”) version of the animation to prepare another (“hand image omitted”) version. The present study has demonstrated that, an individual watching an instructive animation on the porcelain making process, the image of the porcelain maker’s hands can activate the mirror neuron system (MNS). In observations of “tool included” clips, even the “hand image omitted” clip induced significant mu rhythm suppression in the right central area. These results suggest that the visual observation of a tool-based action may be able to activate the MNS even in the absence of hand imagery..
12. Shigekazu Higuchi, Sang Il Lee, Tomoaki Kozaki, Tetsuo Harada, Ikuo Tanaka, Late circadian phase in adults and children is correlated with use of high color temperature light at home at night, Chronobiology International, 10.3109/07420528.2016.1152978, 33, 4, 448-452, 2016.04, Light is the strongest synchronizer of human circadian rhythms, and exposure to residential light at night reportedly causes a delay of circadian rhythms. The present study was conducted to investigate the association between color temperature of light at home and circadian phase of salivary melatonin in adults and children. Twenty healthy children (mean age: 9.7 year) and 17 of their parents (mean age: 41.9 years) participated in the experiment. Circadian phase assessments were made with dim light melatonin onset (DLMO). There were large individual variations in DLMO both in adults and children. The average DLMO in adults and in children were 21:50 ± 1:12 and 20:55 ± 0:44, respectively. The average illuminance and color temperature of light at eye level were 139.6 ± 82.7 lx and 3862.0 ± 965.6 K, respectively. There were significant correlations between color temperature of light and DLMO in adults (r = 0.735, p
13. Shigekazu Higuchi, Yuki Nagafuchi, Sang Il Lee, Tetsuo Harada, Influence of light at night on melatonin suppression in children, Journal of Clinical Endocrinology and Metabolism, 10.1210/jc.2014-1629, 99, 9, 3298-3303, 2014.09, Context: The sensitivity of melatonin to light suppression is expected to be higher in children because children have large pupilsandpure crystal lenses. However, melatonin suppression by light in children remains unclear. Copyright
Objective: We investigated whether light-induced melatonin suppression in children is larger than that in adults.
Methods: Thirty-three healthy primary school children(meanage, 9.2±1.5 y)and29 healthy adults (meanage, 41.6±4.7 y) participated intwoexperiments. In the first experiment, salivary melatonin concentrations in 13 children and 13 adults were measured at night under a dim light (Results: In experiment 1, the melatonin concentration was significantly decreased by exposure to moderately bright light in both adults and children. Melatonin suppression was significantly larger in children (88.2%; n = 5) than in adults (46.3%; n = 6; P Conclusion: We found that the percentage of melatonin suppression by light in children was almost twice that in adults, suggesting that melatonin is more sensitive to light in children than in adults at night..
14. Shigekazu Higuchi, Akiko Hida, Sei Ichi Tsujimura, Kazuo Mishima, Akira Yasukouchi, Sang Il Lee, Youhei Kinjyo, Manabu Miyahira, Melanopsin Gene Polymorphism I394T Is Associated with Pupillary Light Responses in a Dose-Dependent Manner, PLoS One, 10.1371/journal.pone.0060310, 8, 3, 2013.03, Background: Melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs) play an important role in non-image forming responses to light, such as circadian photoentrainment, light-induced melatonin suppression, and pupillary light response. Although it is known that there are some single nucleotide polymorphisms (SNPs) in the melanopsin (OPN4) gene in humans, the associations of the SNPs with non-image forming responses to light remains unclear. In the present study, we examined the associations of melanopsin gene polymorphisms with pupillary light response. Methods: Japanese university students (mean age: 21.0±1.7 years) with the genotypes of TT (n = 38), TC (n = 28) and CC (n = 7) at rs1079610 (I394T) located in the coding region participated in the present study. They were matched by age and sex ratio. Dark-adapted pupil size (
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16. Shigekazu Higuchi, Yutaka Motohashi, Keita Ishibashi, Takafumi Maeda, Influence of eye colors of Caucasians and Asians on suppression of melatonin secretion by light, American Journal of Physiology - Heart and Circulatory Physiology, 10.1152/ajpregu.00355.2006, 292, 6, 2007.06, This experiment tested effects of human eye pigmentation depending on the ethnicity on suppression of nocturnal melatonin secretion by light. Ten healthy Caucasian males with blue, green, or light brown irises (light-eyed Caucasians) and 11 Asian males with dark brown irises (dark-eyed Asians) volunteered to participate in the study. The mean ages of the light-eyed Caucasians and dark-eyed Asians were 26.4 ± 3.2 and 25.3 ± 5.7 years, respectively. The subjects were exposed to light (1,000 lux) for 2 h at night. The starting time of exposure was set to 2 h before the time of peak salivary melatonin concentration of each subject, which was determined in a preliminary experiment. Salivary melatonin concentration and pupil size were measured before exposure to light and during exposure to light. The percentage of suppression of melatonin secretion by light was calculated. The percentage of suppression of melatonin secretion 2 h after the start of light exposure was significantly larger in light-eyed Caucasians (88.9 ± 4.2%) than in dark-eyed Asians (73.4 ± 20.0%) (P
17. Shigekazu Higuchi, Yutaka Motohashi, Yang Liu, Akira Maeda, Effects of playing a computer game using a bright display on presleep physiological variables, sleep latency, slow wave sleep and REM sleep, Journal of Sleep Research, 10.1111/j.1365-2869.2005.00463.x, 14, 3, 267-273, 2005.09, Epidemiological studies have shown that playing a computer game at night delays bedtime and shortens sleeping hours, but the effects on sleep architecture and quality have remained unclear. In the present study, the effects of playing a computer game and using a bright display on nocturnal sleep were examined in a laboratory. Seven male adults (24.7 ± 5.6 years old) played exciting computer games with a bright display (game-BD) and a dark display (game-DD) and performed simple tasks with low mental load as a control condition in front of a BD (control-BD) and DD (control-DD) between 23:00 and 1:45 hours in randomized order and then went to bed at 2:00 hours and slept until 8:00 hours. Rectal temperature, electroencephalogram (EEG), heart rate and subjective sleepiness were recorded before sleep and a polysomnogram was recorded during sleep. Heart rate was significantly higher after playing games than after the control conditions, and it was also significantly higher after using the BD than after using the DD. Subjective sleepiness and relative theta power of EEG were significantly lower after playing games than after the control conditions. Sleep latency was significantly longer after playing games than after the control conditions. REM sleep was significantly shorter after the playing games than after the control conditions. No significant effects of either computer games or BD were found on slow-wave sleep. These results suggest that playing an exciting computer game affects sleep latency and REM sleep but that a bright display does not affect sleep variables..
1. Shigekazu Higuchi, Light and Circadian Rhythm in Children, 第14回国際生理人類学会議, 2019.09.
2. 樋口 重和, Circadian Responses to Spectrum of Light in Primary School Children, 第33回米国睡眠学会(Sleep 2019), 2019.06.
3. Experimental approaches how to prevent light-induced melatonin suppression and circadian rhythm disturbance in shift workers.
4. Higuchi S, Light and Circadian Rhythms, The 11th Joint Workshop on Machine Perception and Robotics (MPR2015), 2015.11.
5. Higuchi S, Effects of Light at Night on Melatonin Suppression and Circadian Phase in Children., The 12th International Congress of Physiological Anthropology, 2015.10.
6. Nishimura Y, Suematsu A, Ikeda Y, Isoda K, Hisanaga I, Kim Y, Higuchi S, Effects of Imitating Experience on Brain Activities while Observing Images with Implied Motions, The 12th International Congress of Physiological Anthropology, 2015.10.
7. Higuchi S, Ota H, Phenotypic variations in non-visual effects of light associated with melanopsin and clock gene polymorphism in human, International Symposium on Human Adaptation to Environment and Whole-body Coordination, 2015.03.
8. Higuchi S, Effects of light before bed time on melatonin suppression and circadian phase in children , 光生物・光化学応用研究フォーラム, 2014.10.
10. Higuchi S, Lee Si, Nagafuchi Y, Harada T, Comparison of light -induced melatonin suppression in children and adults., SLTBR 26th Annual Meeting, 2014.06.
11. Lee Si, Higuchi S, Association between genetic polymorphism of melanopsin photoreceptor and sleep/wake timing, 国際人類学民族科学連合(IUAES), 2014.05, The human sleep/wake cycle is adjusted by circadian rhythms that adapt to a 24-hour light/dark cycle. The melanopsin photoreceptor in the retina plays an important role in circadian photoentrainment in the natural environment. However, artificial light at night has adverse effects on human sleep and circadian rhythm in modern society. We have already found that melanopsin gene polymorphism is associated with pupillary light response, but the association with sleep/wake timing has remained unclear. A total of 348 healthy Japanese university students participated in this study. The genotypes of rs1079610 (I394T) located in the coding region were analyzed. Bedtime, wake time and midpoint of sleep on weekdays of CC subjects were significantly later than those of TT and TC subjects. We have already found that pupilloconstriction in subjects with the C allele is highly responsive to light. The delayed sleep/wake timing of CC subjects might be a consequence of the high responsiveness to light at night since exposure to light at night induces phase delay. C allele frequency of I394T in the European population is larger than that in the Asian-Japanese and Sub-saharan African populations. High responsiveness to light may be an adaptive trait for a short photoperiod in European people living in high latitude areas. However, our results suggest that high responsiveness to light is a cause of delayed sleep timing in adolescents living under artificial light at night in modern society..
12. Shigekazu HIGUCHI, Association between melanopsin gene polymorphism and non-visual response to light, SLTBR Annual Meetings, 2012.06.