Details of a Researcher - Ikaga, Toshiharu

Papers - Ikaga, Toshiharu

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Association between Indoor Temperature in Winter and Serum Cholesterol: A Cross-Sectional Analysis of the Smart Wellness Housing Survey in Japan.

Wataru Umishio, Toshiharu Ikaga, Kazuomi Kario, Yoshihisa Fujino, Masaru Suzuki, Tanji Hoshi, Shintaro Ando, Takesumi Yoshimura, Hiroshi Yoshino, Shuzo Murakami

Journal of atherosclerosis and thrombosis (Journal of Atherosclerosis and Thrombosis) 29 ( 12 ) 1791 - 1807 2022.05

Research paper (scientific journal), Joint Work, Corresponding author, Accepted, ISSN 13403478

AIM: Issuance of the WHO Housing and health guidelines has paralleled growing interest in the housing environment. Despite accumulating evidence of an association between outdoor temperature and serum cholesterol, indoor temperature has not been well investigated. This study examined the association between indoor temperature and serum cholesterol. METHODS: We collected valid health checkup data of 2004 participants (1333 households), measured the indoor temperature for 2 weeks in winter, and divided participants according to whether they lived in a warm (average bedroom temperature ≥ 18℃), slightly cold (12-18℃) or cold house (＜12˚C). The relationship between bedroom temperature and serum cholesterol was analyzed using multivariate logistic regression models, adjusting for demographics, lifestyle habits and the season in which the health checkup was conducted, with a random effect of climate areas in Japan. RESULTS: The sample sizes for warm, slightly cold, and cold houses were 206, 940, and 858, respectively. Compared to those in warm houses, the odds ratio of total cholesterol exceeding 220 mg/dL was 1.83 (95%CI: 1.23-2.71, p=0.003) for participants in slightly cold houses and 1.87 (95%CI: 1.25-2.80, p=0.002) in cold houses. Similarly, the odds ratio of LDL/non-HDL cholesterol exceeding the standard range was 1.49 (p=0.056)/1.67 (p=0.035) for those in slightly cold houses and 1.64 (p=0.020)/1.77 (p=0.021) in cold houses. HDL cholesterol and triglycerides were not significantly associated with bedroom temperature. CONCLUSION: Besides lifestyle modification, improving indoor thermal environment through strategies such as installing high thermal insulation and appropriate use of heating devices may contribute to better serum cholesterol condition.

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Frontotemporal EEG as potential biomarker for early MCI: a case-control study.

Yasue Mitsukura, Brian Sumali, Hideto Watanabe, Toshiharu Ikaga, Toshihiko Nishimura

BMC psychiatry (BMC) 22 ( 1 ) 289 - 289 2022.04

Research paper (scientific journal), Joint Work, Accepted

BACKGROUND: Previous studies using EEG (electroencephalography) as biomarker for dementia have attempted to research, but results have been inconsistent. Most of the studies have extremely small number of samples (average N = 15) and studies with large number of data do not have control group. We identified EEG features that may be biomarkers for dementia with 120 subjects (dementia 10, MCI 33, against control 77). METHODS: We recorded EEG from 120 patients with dementia as they stayed in relaxed state using a single-channel EEG device while conducting real-time noise reduction and compared them to healthy subjects. Differences in EEG between patients and controls, as well as differences in patients' severity, were examined using the ratio of power spectrum at each frequency. RESULTS: In comparing healthy controls and dementia patients, significant power spectrum differences were observed at 3 Hz, 4 Hz, and 10 Hz and higher frequencies. In patient group, differences in the power spectrum were observed between asymptomatic patients and healthy individuals, and between patients of each respective severity level and healthy individuals. CONCLUSIONS: A study with a larger sample size should be conducted to gauge reproducibility, but the results implied the effectiveness of EEG in clinical practice as a biomarker of MCI (mild cognitive impairment) and/or dementia.

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Quantitative Evaluation of the Contributions of Improved Housing Performances Toward Delivering Sustainable Development Goals by a Building Energy Simulation Tool

Mao Serikawa, Makoto Satoh, Wataru Umishio, Shun Kawakubo, Junta Nakano, Takashi Akimoto, Toshiharu Ikaga, Shuzo Murakami

Sustainable Cities and Society (ELSEVIER) 79 2022.04

Research paper (scientific journal), Joint Work, Accepted, ISSN 2210-6707

In 2015, the 2030 Agenda for Sustainable Development Goals (SDGs) was adopted by all United Nations Member States. The indoor environment of residences affects the health of occupants regarding SDG 3 (Good Health and Well-being). Meanwhile, a vast amount of energy is used to supply power to houses worldwide, which emit sufficient volumes of CO2 and affect climate change regarding SDG 7 (Affordable and Clean Energy) and SDG 13 (Climate Action). A key step to delivering on these SDGs is improving the thermal insulation of houses and housing equipment performance to reduce energy consumption and protect the health of the occupants by improving the indoor environment. This study presents an evaluation method for quantifying the contribution of improving housing performance toward delivering the SDGs. The proposed approach is primarily based on the results of heat load simulations. Meanwhile, blood pressure is predicted as an indicator of health by using the interior environment obtained by the simulation. A case study was performed, and the results demonstrated the effectiveness of improving the housing performance of newly constructed houses compared to heating and retrofit. The proposed method is versatile and can be adjusted for application to alternative locations, house designs, and lifestyles.

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冬季における住宅内室温と外気温の実態とその関連　SWH横断調査

星旦二, 伊香賀俊治, 海塩渉, 藤野善久, 安藤真太朗, 吉村健清

日本公衆衛生雑誌 (日本公衆衛生学会) 69 ( 4 ) 297 - 306 2022.04

Research paper (scientific journal), Joint Work, Accepted, ISSN 0546-1766

目的本研究の目的は,我が国の冬期における戸建て住宅各室の室温と外気温の実態と共にその関連性について,国土交通省の定める省エネ地域区分別に明確にすることである。方法本研究の対象者は,日本全国に居住している3,781人である。調査は2014年度冬季より,国土交通省の支援を得て全国的に実施されている,SWH(Smart Wellness Housing)事業の一環として5年間実施した。各部屋別(居間・寝室・脱衣所)に測定された冬期二週間の床上1m室温と床近傍室温,それに気象庁が測定した外気温の実態とともに,その関連について共分散構造分析を用いて解析した。これらの関連は,同時分析により全国の省エネ地域区分別に解析した。分析ソフトは,SPSS22.0とAMOS22.0を用いた。結果冬季における住居内床近傍室温は床上1m室温よりも低く,時間帯でみると床近傍ないし室温共に朝が低い温度を示した。部屋別室温較差は,居間と脱衣所間で大きかった。室温を地域別にみると,省エネ地域2の室温が最も高く,省エネ地域4の室温が最も低いことが示された。冬期の外気温は各室温よりも床近傍室温と強い関連がみられた。結論我が国の住宅床近傍室温は,床上1m室温よりも低いことと,居間と脱衣所とでは大きな温度較差がみられた。省エネ地域区分4の住宅床近傍室温と床上1m室温が最も低いことが示された。室温が外気温から影響される度合いは,省エネ地域7を除き地域番号とともに大きくなることが示された。(著者抄録)

Proposal of net-zero energy house by introducing environmentally friendly PV/T solar panels

TERASHIMA Kohei, SATO Haruki, IKAGA Toshiharu

Journal of Japan Solar Energy Society (Japan Solar Energy Society) 48 ( 2 ) 61 - 70 2022.03

Research paper (scientific journal), Joint Work, Last author, Corresponding author, Accepted, ISSN 0388-9564

Solar energy would be the most important energy resource. The highest performance solar-energy receiver recorded utilizing 74.3 % of the solar energy in total of electricity and 40 °C hot water in summer, Yokohama, Japan, has already been reported in 2020 as a photovoltaic/Thermal (PV/T) solar panel. In this paper, the system design on introducing the PV/T solar panel to be a part of energy-supply system in a household and the simulation results are reported. Using a Monte Carlo simulation method, it can generate different energy demands at every 15 minutes through a year for various family members as the simulation calculation, while the results always follow the input existing statistics information. Not only solar-energy management in a household but also the environmental thermal load is evaluated. An example of the net-zero energy house having the best combination of the environmentally friendly PV/T and PV solar panels is presented in this paper.

Descriptive epidemiology of winter indoor and outdoor temperatures and their relationships based on SWH survey

HOSHI Tanji, IKAGA Toshiharu, UMISHIO Wataru, FUJINO Yoshihisa, ANDO Shintaro, YOSHIMURA Takesumi

Nihon Koshu Eisei Zasshi(JAPANESE JOURNAL OF PUBLIC HEALTH) (Japanese Society of Public Health) advpub ( 4 ) 297 - 306 2022

Research paper (scientific journal), Joint Work, Accepted, ISSN 0546-1766

Objectives The purpose of this study was to make clear the descriptive epidemiology and the relationship between the room temperature of living room, bedroom, dressing room, and outdoor during winter, based on the climate areas in Japan.

Methods This study targeted 3,781 people, survey for 5 years from 2014, based on the Smart Wellness Housing (SWH) project, which was carried out nationwide with the support of the Ministry of Land, Infrastructure, Transport and Tourism. During winter, we recorded the outdoor temperature and living room, bedroom, and dressing room temperatures at 1 m above the floor and near the floor for two weeks. Covariance structure analyses were used to clarify the relationship between room temperature and outdoor temperature based on six climate areas in Japan. The analyses were performed using SPSS22.0 and AMOS22.0 for Windows.

Results The temperature near the floor inside the house was lower than the room temperature at 1 m above the floor, and both the room and near the floor temperature in the morning tended to be the lowest. The temperature disparity between the dressing room and living room was the largest. Based on climate areas, the room temperature in the Area 2 was the highest, while the room temperature in the Area 4 was the lowest. The outdoor temperature was more closely associated with the room temperature near the floor than the room temperature at 1 m above the floor, especially in the southern Areas, except Area 7.

Conclusion The temperature near the floor inside the house was lower than room temperature at 1 m above the floor. The temperature disparity between dressing room and living room was the largest. The room temperature and near the floor temperature were lowest in the energy-saving Area 4. The outdoor temperature was more closely associated with the room temperature near the floor than the room temperature at 1 m above the floor, especially in the southern Areas, except Area 7.

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CASBEE-オフィス健康チェックリストを用いたWEBアンケートの追跡調査結果

森重優子, 白石靖幸, 安部祐子, 林立也, 伊香賀俊治, 藤野善久

空気調和・衛生工学会大会学術講演論文集 (公益社団法人空気調和・衛生工学会) 2022.8 93 - 96 2022

Research paper (scientific journal), Joint Work, Accepted, ISSN 1880-3806

近年、地域や職場等を通じた健康増進への働きかけが注目されている。この流れより執務環境の主観評価ツールであるCASBEE-OHCの開発とそのチェックリストを用いたWEBアンケート調査が行われた。しかし現在、オフィス環境やワーカーを取り巻く環境の変化が予想される。そこで本研究では、現在の環境について新たな知見を得るため、再度調査を実施した。結果として、現在、執務者の健康には住まいの環境や家での執務環境の影響が関係していることが確認された。

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Housing quality and behavior affect brain health and anxiety in healthy Japanese adults.

Juan Cesar D Pineda, Keisuke Kokubun, Toshiharu Ikaga, Yoshinori Yamakawa

Scientific reports (NATURE PORTFOLIO) 11 ( 1 ) 11999 - 11999 2021.12

Research paper (scientific journal), Joint Work, Accepted, ISSN 2045-2322

Countless studies in animals have shown how housing environments and behaviors can significantly affect anxiety and brain health, giving valuable insight as to whether this is applicable in the human context. The relationship between housing, behavior, brain health, and mental wellbeing in humans remains poorly understood. We therefore explored the interaction of housing quality, weekend/holiday sedentary behavior, brain structure, and anxiety in healthy Japanese adults. Whole-brain structural magnetic resonance imaging (MRI) methods based on gray matter volume and fractional anisotropy were used as markers for brain health. Correlation tests were conducted, and then adjusted for multiple comparisons using the False Discovery Rate method. Housing quality and weekend/holiday sedentary behavior were associated with fractional anisotropy, but not with gray matter volume. Fractional anisotropy showed significant associations with anxiety. Lastly, both weekend/holiday sedentary behavior and housing quality were indirectly associated with anxiety through fractional anisotropy. These results add to the limited evidence surrounding the relationship among housing, behavior, and the brain. Furthermore, these results show that behavior and housing qualities can have an indirect impact on anxiety through neurobiological markers such as fractional anisotropy.

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Electrocardiogram abnormalities in residents in cold homes: a cross-sectional analysis of the nationwide Smart Wellness Housing survey in Japan

Wataru Umishio, Toshiharu Ikaga, Kazuomi Kario, Yoshihisa Fujino, Masaru Suzuki, Shintaro Ando, Tanji Hoshi, Takesumi Yoshimura, Hiroshi Yoshino, Shuzo Murakami

Environmental Health and Preventive Medicine (SPRINGER) 26 ( 1 ) 104 - 104 2021.12

Research paper (scientific journal), Joint Work, Accepted, ISSN 1342078X

Background: Excess winter mortality caused by cardiovascular disease is particularly profound in cold houses. Consistent with this, accumulating evidence indicates that low indoor temperatures at home increase blood pressure. However, it remains unclear whether low indoor temperatures affect other cardiovascular biomarkers. In its latest list of priority medical devices for management of cardiovascular diseases, the World Health Organization (WHO) included electrocardiography systems as capital medical devices. We therefore examined the association between indoor temperature and electrocardiogram findings. Methods: We collected electrocardiogram data from 1480 participants during health checkups. We also measured the indoor temperature in the living room and bedroom for 2 weeks in winter, and divided participants into those living in warm houses (average exposure temperature ≥ 18 °C), slightly cold houses (12–18 °C), and cold houses (< 12 °C) in accordance with guidelines issued by the WHO and United Kingdom. The association between indoor temperature (warm vs. slightly cold vs. cold houses) and electrocardiogram findings was analyzed using multivariate logistic regression models, with adjustment for confounders such as demographics (e.g., age, sex, body mass index, household income), lifestyle (e.g., eating habit, exercise, smoking, alcohol drinking), and region. Results: The average temperature at home was 14.7 °C, and 238, 924, and 318 participants lived in warm, slightly cold, and cold houses, respectively. Electrocardiogram abnormalities were observed in 17.6%, 25.4%, and 30.2% of participants living in warm, slightly cold, and cold houses, respectively (p = 0.003, chi-squared test). Compared to participants living in warm houses, the odds ratio of having electrocardiogram abnormalities was 1.79 (95% confidence interval: 1.14–2.81, p = 0.011) for those living in slightly cold houses and 2.18 (95% confidence interval: 1.27–3.75, p = 0.005) for those living in cold houses. Conclusions: In addition to blood pressure, living in cold houses may have adverse effects on electrocardiogram. Conversely, keeping the indoor thermal environment within an appropriate range through a combination of living in highly thermal insulated houses and appropriate use of heating devices may contribute to good cardiovascular health. Trial registration: The trial was retrospectively registered on 27 Dec 2017 to the University hospital Medical Information Network Clinical Trials Registry (UMIN-CTR, https://www.umin.ac.jp/ctr/, registration identifier number UMIN000030601).

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Impact of indoor temperature instability on diurnal and day-by-day variability of home blood pressure in winter: a nationwide Smart Wellness Housing survey in Japan

Wataru Umishio, Toshiharu Ikaga, Kazuomi Kario, Yoshihisa Fujino, Masaru Suzuki, Shintaro Ando, Tanji Hoshi, Takesumi Yoshimura, Hiroshi Yoshino, Shuzo Murakami

Hypertension Research (Springer Science and Business Media LLC) 44 ( 11 ) 1406 - 1416 2021.11

Research paper (scientific journal), Joint Work, Accepted, ISSN 09169636

<title>Abstract</title>Home blood pressure (HBP) variability is an important factor for cardiovascular events. While several studies have examined the effects of individual attributes and lifestyle factors on reducing HBP variability, the effects of living environment remain unknown. We hypothesized that a stable home thermal environment contributes to reducing HBP variability. We conducted an epidemiological survey on HBP and indoor temperature in 3785 participants (2162 households) planning to have their houses retrofitted with insulation. HBP was measured twice in the morning and evening for 2 weeks in winter. Indoor temperature was recorded with each HBP observation. We calculated the morning-evening (ME) difference as an index of diurnal variability and the standard deviation (SD), coefficient of variation (CV), average real variability (ARV) and variability independent of the mean (VIM) as indices of day-by-day variability. The association between BP variability and temperature instability was analyzed using multiple linear regression models. The mean ME difference in indoor/outdoor temperature (a decrease in temperature overnight) was 3.2/1.5 °C, and the mean SD of indoor/outdoor temperature was 1.6/2.5 °C. Linear regression analyses showed that the ME difference in indoor temperature was closely correlated with the ME difference in systolic BP (0.85 mmHg/°C, <italic>p</italic> < 0.001). The SD of indoor temperature was also associated with the SD of systolic BP (0.61 mmHg/°C, <italic>p</italic> < 0.001). The CV, ARV, and VIM showed similar trends as the SD of BP. In contrast, outdoor temperature instability was not associated with either diurnal or day-by-day HBP variability. Therefore, residents should keep the indoor temperature stable to reduce BP variability.

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特集健康的な住まいが欲しい!-暮らしやすくて,寿命も延びる健康長寿に資する住まいと住まい方

伊香賀俊治

公衆衛生 (株式会社医学書院) 85 ( 7 ) 443 - 449 2021.07

Research paper (scientific journal), Joint Work, Accepted, ISSN 03685187

Prospective cohort study of bedroom heating and risk of common cold in children.

Ishimaru T, Mine Y, Odgerel CO, Miyake F, Kubo T, Ikaga T, Fujino Y

Pediatrics international : official journal of the Japan Pediatric Society (Wiley) 64 ( 1 ) e14755 2021.04

Research paper (scientific journal), Joint Work, Accepted, ISSN 1328-8067

BACKGROUND: In countries with mild winter climates and inadequate heating, the relationship between housing conditions and health outcomes in winter have not been well studied. The purpose of present study was to evaluate the relationship between heater type and temperature factors in the bedroom and incidence of the common cold among children in Japan. METHODS: In this prospective cohort study, we distributed baseline questionnaires and temperature loggers in December 2019 and administered follow-up questionnaires in March 2020. We recruited children under age 15 years. We performed Poisson regression analysis and logistic regression analysis. RESULTS: Of 297 participants, air conditioners were the most prevalent (n=105, 35%), followed by gas or kerosene heaters (n=50, 17%) and floor heaters (n=31, 10%). Air-conditioners were associated with higher incidence of all events related to the common cold, especially having a fever (adjusted incidence rate ratio (aIRR)=1.84, 95% confidence interval (CI): 1.41-2.40). Contrary, gas or kerosene and floor heaters showed a lower incidence rate of some events related to the common cold, such as school or nursery school absence (aIRR=0.55, 95% CI: 0.37-0.82 and aIRR=0.39, 95% CI: 0.23-0.67, respectively). Whereas bedroom temperature did not show a positive association, children who always felt cold showed a higher incidence of some events related to the common cold. CONCLUSIONS: Our findings imply that the heating approach and modal thermal comfort, such as location of heating appliances, humidity, airflow, and radiant heat, may be more important for the onset of common cold in children than bedroom temperature itself.

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成人における冬季の住宅内の暖房使用と座位行動および身体活動　スマートウェルネス住宅調査による横断研究

伊藤真紀, 伊香賀俊治, 小熊祐子, 齋藤義信, 藤野善久, 安藤真太朗, 村上周三, スマートウェルネス住宅調査グループ

運動疫学研究: Research in Exercise Epidemiology (日本運動疫学会) 23 ( 1 ) 45 - 56 2021.03

Research paper (scientific journal), Joint Work, Accepted, ISSN 1347-5827

目的:成人を対象に,冬季の暖房使用と住宅内の座位行動および身体活動の関連を検討すること。方法:本研究は横断研究である。調査は沖縄県を除く46都道府県の工務店等を通して募集した断熱改修工事予定のある住宅に居住する20歳以上の成人を対象に2014年度から2017年度までの冬季(11月〜4月)に実施し,3,874名から同意を得た。加速度計は連続14日間の装着を依頼した。行動日誌から覚醒在宅時間帯を特定し,住宅内の座位行動と身体活動を評価した。コタツおよび脱衣所暖房使用の有無と住宅内の座位行動,身体活動との関連は目的変数を対数変換したうえで,日レベル(室温,オフセット項として覚醒在宅時加速度計装着時間等),個人レベル(年齢,BM等),世帯レベル(世帯年収,同居人数等)で調整した線形混合モデル(ランダム切片モデル)を男女別に実施した。非標準化偏回帰係数は指数変換し,目的変数への関連の程度を算出した。結果:有効データは3,482名であった。多変量解析の結果,コタツを使用しない場合は住宅内の座位行動時間が約2%短く[男性:exp(B)=0.98,p=0.022,女性:exp(B)=0.98,p=0.020],その中断回数は約10%多く[男性:exp(B)=1.10,p=0.001,女性:exp(B)=1.11,p<0.001],身体活動も5〜7%多かった[男性:exp(B)=1.07,p=0.005,女性:exp(B)=1.05,p=0.012]。脱衣所を暖房する場合も同様の関連が確認された。結論:コタツを使用しない人,脱衣所を暖房する人は,住宅内の座位行動時間が短く,かつ頻繁に中断し,身体活動量も多かった。局所暖房を使用せず,非居室でも暖房を行い家を暖かく保つことは,住宅内の座位行動を抑制し身体活動を促進する可能性がある。(著者抄録)

ASSOCIATION BETWEEN FEELING COLD IN THE BEDROOM AND THE INCIDENCE OF UPPER RESPIRATORY INFECTION SYMPTOMS

Odgerel Chimed-Ochir, Yoshihisa Fujino, Yuko Mine, Toshiharu Ikaga, Tomohiro Ishimaru, Tatsuhiko Kubo

SOUTHEAST ASIAN JOURNAL OF TROPICAL MEDICINE AND PUBLIC HEALTH (SOUTHEAST ASIAN MINISTERS EDUC ORGANIZATION) 52 ( 1 ) 86 - 95 2021.02

Research paper (scientific journal), Joint Work, Accepted, ISSN 01251562

A cold ambient temperature in the house may be associated with risk of respiratory infection. In this study, we aimed to determine if there is a significant association between a perception of a cold bedroom and the presence of upper respiratory infection symptoms in order to inform efforts to reduce the incidence of upper respiratory infections in the study population. For this study, subjects were purposely selected from employees and their spouses of a single company in Kyushu, Japan. The study was conducted from December 2018 to March 2019. Each subject was asked to complete a self-administered questionnaire and which best classified how they felt at bedtime: never, sometimes or always. Each subject was also asked whether they had upper respiratory tract infection symptoms, whether they took over-the-counter medication or saw a physician for their symptoms. Between-group differences were examined for significance using the Chi square test. Logistic regression analysis was used to evaluate the potential association between the level of perceived coldness and the likelihood of having an upper respiratory tract infection and its consequences. A total of 1196 subjects were included in the study, 64% male (826 employees (89% male) and 370 spouses (8% male)). The mean age of study subjects was 44 (+/- 12) years. Of the total subjects, 44%, 44% and 12% never/rarely felt cold at bedtime, sometimes felt cold at bedtime and often/always felt cold at bedtime, respectively. Of the total subjects, 52% had upper respiratory tract infection symptoms. When compared with subjects who never/rarely felt cold, subjects who always/often felt cold had significantly greater odds of having upper respiratory tract infection symptoms (adjusted odds ratio (adjusted OR) = 2.56; 95% confidence interval (CI): 1.33-4.91; p = 0.005), having taken over-the-counter drugs for upper respiratory tract infection symptoms (adjusted OR = 1.90; 95% CI: 1.95-2.91; p = 0.003), having taken sick leave for an upper respiratory tract infection (adjusted OR = 3.54; 95% CI: 1.63-7.69; p = 0.001) and having visited a doctor for upper respiratory tract infection symptoms (adjusted OR = 3.22; 95% CI: 1.18-8.80; p = 0.022). In our study population, feeling cold in the bedroom at nighttime was significantly associated with having upper respiratory tract infection symptoms, visiting a doctor and taking sick leave. A change in the room temperature at nighttime should be considered for those who feel cold at nighttime. Further studies are needed to determine if changing the temperature of the bedroom so the person does not feel cold at nighttime will result in fewer episodes of upper respiratory tract infections or not.

Protein intake in inhabitants with regular exercise is associated with sleep quality: Results of the Shika study.

Fumihiko Suzuki, Emi Morita, Sakae Miyagi, Hiromasa Tsujiguchi, Akinori Hara, Thao Thi Thu Nguyen, Yukari Shimizu, Koichiro Hayashi, Keita Suzuki, Takayuki Kannon, Atsushi Tajima, Sumire Matsumoto, Asuka Ishihara, Daisuke Hori, Shotaro Doki, Yuichi Oi, Shinichiro Sasahara, Makoto Satoh, Ichiyo Matsuzaki, Masashi Yanagisawa, Toshiharu Ikaga, Hiroyuki Nakamura

PloS one (PUBLIC LIBRARY SCIENCE) 16 ( 2 February ) e0247926 2021.02

Research paper (scientific journal), Joint Work, Accepted, ISSN 1932-6203

STUDY OBJECTIVES: Although associations between sleep quality and environmental factors and nutrient intake have been reported, interactions between these factors have not been elucidated in detail. Therefore, this cross-sectional study examined the effects of regular exercise and nutrient intake on sleep quality using the Pittsburgh Sleep Quality Index (PSQI), which is the most frequently used index for sleep evaluation. METHODS: The participants included 378 individuals aged 40 years or older living in Shika Town, Ishikawa Prefecture. Of these individuals, 185 met the inclusion criteria. The participants completed a self-administered questionnaire assessing lifestyle habits and frequency and duration of exercise, the PSQI, and the brief-type self-administered diet history questionnaire (BDHQ) on nutrient intake. RESULTS: A two-way analysis of covariance on regular exercise and PSQI scores indicated that protein intake (17.13% of energy) was significantly higher in the regular exercise and PSQI ≤10 groups than in the non-regular exercise or PSQI ≥11 groups (p = 0.002). In a multiple logistic regression analysis with PSQI scores (≤10 and ≥11), protein intake was a significant independent variable in any of the models adjusted for confounding factors such as age, sex, body mass index, current smoker, and current drinker (OR: 1.357, 95% CI: 1.081, 1.704, p = 0.009) in the regular exercise group but not in the non-regular exercise group.Conclusions We identified a positive relationship between sleep quality and protein intake in the regular exercise group. These findings suggest that regular exercise at least twice a week for 30 minutes or longer combined with high protein intake contributes to good sleep quality.

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Heating use and sedentary behavior and physical activity at home among adults in winter: a cross-sectional analysis of the Nationwide Smart Wellness Housing Survey in Japan

Ito Maki, Ikaga Toshiharu, Oguma Yuko, Saito Yoshinobu, Fujino Yoshihisa, Ando Shintaro, Murakami Shuzo, the Smart Wellness Housing survey group

Research in Exercise Epidemiology (Japanese Association of Exercise Epidemiology) 23 ( 1 ) 45 - 56 2021

Research paper (scientific journal), Joint Work, Accepted, ISSN 1347-5827

Objective: This study examined the association between use of heating and sedentary behavior (SB) and physical activity (PA) at home among Japanese adults in winter. Methods: This cross-sectional study was conducted from November to April from 2014 to 2017. Participants (N=3,874) who intended to conduct insulation retrofitting were recruited by construction companies from 46 prefectures excluding Okinawa Prefecture and wore an accelerometer on their waist for 2 weeks. The association between heating use and log-transformed SB and PA at home was analyzed using a sex-stratified multilevel model (random-intercept model) with 3 levels; day-level variables (e.g., indoor temperature and log-transformed accelerometer wear time as an offset), nested within individual-level (e.g., age and body mass index), and nested within household-level (e.g., household income, number of housemates). The degree of association with the dependent variable was given by exponential transforming the unstandardized regression coefficient. Results: Data from 3,482 participants were analyzed. In the multilevel model, not using a kotatsu was associated with about 2% shorter SB time [men: exp(B)=0.98, p=0.022; women: exp(B)=0.98, p=0.020], an about 10% greater number of breaks in SB time [men: exp(B)=1.10, p=0.001; women: exp(B)=1.11, p<0.001], and 5-7% greater PA [men: exp(B)=1.07, p=0.005; women: exp(B)=1.05, p=0.012] than using a kotatsu. Heating the changing room was also related to shorter SB time, a greater number of breaks in SB time and greater PA in men and women. Conclusions: Not using a kotatsu and heating the changing room were associated with shorter SB and greater PA at home. Warming by heating the entire home, rather than partially heating just the living room, may decrease SB and increase PA in winter.

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STUDY ON DIFFERENT OFFICE COOLING SYSTEMS ON WORKERS BY SUBJECT EXPERIMENT (PART 1): EFFECTS OF INDOOR ENVIRONMENT DIFFERENCE DUE TO OFFICE COOLING SYSTEMS ON SKIN TEMPERATURE, PSYCHOLOGICAL QUANTITY, AND WORKPLACE PRODUCTIVITY

YANASE Tomoki, IKAGA Toshiharu, SATOU Noriaki, SHIMIZU Hiroshi, ITO Sei, KAWAKAMI Risa

Journal of Environmental Engineering (Transactions of AIJ) (Architectural Institute of Japan) 86 ( 781 ) 205 - 214 2021

Research paper (scientific journal), Joint Work, Accepted, ISSN 1348-0685

Increasing the workplace productivity of workers has great economic value and is essential for achieving a sustainable society and economic progress. One way to increase workplace productivity is to improve the work environment, which is important because of its strong influence on workers. The work environment can be improved by using air conditioning to change the thermal environment. In Japan, radiant air-conditioning has received attention as a means to realize energy-saving buildings. However, the difference between the effects of radiant air-conditioning vs. convective air-conditioning on the human body is not clear. Therefore, in this study, we examined these effects on the physiology, psychology, and workplace productivity of workers. In February 2019, we conducted a 5-day experiment with 24 university students (12 males, 12 females). Rooms simulating office conditions were equipped with either a radiant or convection unified air-conditioning system (unified SET*, 27.2°C). In the rooms, the students simulated work such as typing, performing calculations, and creating mind maps between 9:00 and 17:00, changing rooms each day. Physiological measurements such as skin temperature were taken to evaluate stress levels, and a questionnaire was completed by the students to determine perceived comfort. Workplace productivity was evaluated based on the results of the simulated work and questionnaires. The following findings were obtained by this experiment. 1. The skin temperature difference between hands and face (hand-face) was significantly greater in convection air conditioning than in radiant air conditioning for both male and female. It was confirmed that the decrease in the skin surface temperature of the hand with respect to the face had a correlation with psychological quantities such as a decrease in thermal environment satisfaction, a decrease in air flow comfort, and an increase in subjective symptoms. 2. Thermal environment satisfaction was significantly improved in male during convection air conditioning and in female during radiant air conditioning. 3. Thermal environment satisfaction had the strongest correlation with airflow velocity. Focusing on the correlation between thermal environment satisfaction and air velocity during convection air conditioning, positive correlations were found for male and negative correlations for female, confirming different trends for male and female. 4. Focusing on airflow speed and airflow comfort, male tended to improve airflow comfort slightly when airflow speed was high, whereas female showed a marked decrease in airflow comfort when airflow speed was high. The preference for airflow was different between male and female. 5. The more comfortable the air flow was, the less fatigue was felt. 6. For female, comparing radiant air conditioning with convection air conditioning, convection air conditioning increased the rate of "yawning" subjective symptoms by 17.6% and "sleeping" by 8.3%. Other complaints regarding fatigue were also increasing, and it is considered that the unpleasant airflow led to drowsiness and fatigue. 7. Regarding work performance, we performed a multi-level logistic regression analysis with fatigue as an explanatory variable. The ratio of work scores "individual deviation value of 50 or more" is 2.0 to 2.9 times significantly higher when not feeling fatigued than when feeling fatigued in calculation, typing, mind map and all simulated work.

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Effect of housing condition on quality of life

Odgerel Chimed‐Ochir, Toshiharu Ikaga, Shintaro Ando, Tomohiro Ishimaru, Tatsuhiko Kubo, Shuzo Murakami, Yoshihisa Fujino

Indoor Air (Wiley) 31 ( 4 ) 1029 - 1037 2021

Research paper (scientific journal), Joint Work, Accepted, ISSN 09056947

This study examined the housing effect on quality of life among Japanese people. In the current cross-sectional study, we analyzed the 1-year of data (November 2015-March 2016) with 2533 participants. We used the Short Form-8 questionnaire, an 8-item instrument that measures general aspects of health-related QOL. Comprehensive Assessment System for Built Environment Efficiency housing checklist which was developed by Ministry of Land, Infrastructure, Transport and Tourism was used to assess the housing aspects. This checklist has six health elements including thermal comfort, acoustic environment, lighting environment, hygiene, safety, and security for 8 distinctive rooms/places of home. Multilevel analysis was done to identify the relationship between the perceived level of housing problem and PCS and MCS by clustering by sex. Compared to those who always felt unsafe at home due to interior design problem, participants who never felt unsafe showed an average of 10.51 (95% CI = 7.69-13.34, p < 0.0001) and 5.78 (95% CI = 2.90-8.65, p < 0.0001) higher physical and mental component score (better quality of life), respectively. Those who never had thermal, acoustic, lighting, hygiene, and security problems of housing also exhibited significantly better quality of life compared to participants who felt these problems.

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A Prospective Cohort Study of Bedroom Warming With a Heating System and Its Association With Common Infectious Diseases in Children During Winter in Japan

Fuyu Miyake, Chimed-Ochir Odgerel, Yuko Mine, Tatsuhiko Kubo, Toshiharu Ikaga, Yoshihisa Fujino

Journal of Epidemiology (Japan Epidemiological Association) 31 ( 3 ) 165 - 171 2021

Research paper (scientific journal), Joint Work, Accepted, ISSN 09175040

BACKGROUND: Customarily, bedrooms in Japan are left unheated. Although several studies have reported that the use of a heating system has positive outcomes on respiratory infection and asthma, the preventive effect of heating systems against infectious diseases in children is not well known. METHODS: We conducted a cohort study using two questionnaire surveys, one before the winter season in November, 2018 and the second after winter in March, 2019. Participants were 155 children who did not use a heating system in the bedroom and 156 children who did. RESULTS: Having a heated bedroom with a heating system was associated with decreased odds for the frequency of cold (≥3 times) (adjust odds ratio [AOR] 0.35; 95% confidence interval [CI], 0.19-0.65), duration of fever (≥3 days) (AOR 0.38; 95% CI, 0.22-0.66), duration of medicine for a cold (≥3 days) (AOR 0.91; 95% CI, 0.87-0.95), hospital visit due to cold (≥3 days) (AOR 0.54; 95% CI, 0.31-0.94), absence from school or nursery (≥3 days) (AOR 0.43; 95% CI, 0.27-0.70), influenza infection (AOR 0.43; 95% CI, 0.26-0.71), and gastroenteritis (AOR 0.39; 95% CI, 0.21-0.72). Influenza vaccination reduced the odds of influenza infection (AOR 0.36; 95% CI, 0.22-0.59) and absence from school or nursery (≥3 days) (AOR 0.62; 95% CI, 0.39-0.99). CONCLUSION: This study implies that the heating of bedrooms may have a preventive effect against infections among children. Broader dissemination of this knowledge in Japan will require cultural change through public health awareness.

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Perception of feeling cold in the bedroom and sleep quality.

Odgerel Chimed-Ochir, Shintaro Ando, Shuzo Murakami, Tatsuhiko Kubo, Tomohiro Ishimaru, Yoshihisa Fujino, Toshiharu Ikaga

Nagoya journal of medical science (NAGOYA UNIV, SCH MED) 83 ( 4 ) 705 - 714 2021

Research paper (scientific journal), Joint Work, Accepted, ISSN 00277622

Sleep disorders are drawing the attention of both medical and public health concern worldwide. In Japan, research suggests that one fifth of adults do not receive appropriate sleep and 40% of adults sleep less than 6 hours a day, and sleep rates are decreasing further year by year. Many studies show that cold indoor environments negatively affect sleep comfort and quality. Whereas these studies have focused on the effects of low bedroom temperature, few studies have focused on the effect of perception of coldness. Indoor temperature is typically much lower in Japan than in other countries. Therefore, the current study aimed to identify the effect of perception of bedroom coldness on sleep quality among Japanese adults. After controlling for covariates of age, presence of current disease and pain, smoking and consumption of alcohol (Model 1), participants who sometimes, often or always felt cold in the bedroom exhibited 0.57 (95% CI=0.32-0.83, p=<.0001), 1.08 (95% CI=0.82-1.35, p<.0001) or 2.25 (95% CI=1.83-2.67, p<.0001) higher PSQI scores compared to the group which didn't feel cold in bedroom. Our findings suggest keeping the bedroom thermal environment above a minimum limit as recommended by the World Health Organization or other organization during colder, winter nights when feeling cold during sleep. Additional deficiencies in the housing infrastructure, air quality issues due to the use of a heater, and micro bed environment need to be holistically addressed. Sleep quality can be improved by certain level via providing thermally comfortable sleeping environment.

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