The rapid urbanization in Southeast Asia has resulted in an increase in vertical apartment buildings, bringing notable changes in residents’ lifestyles accompanied by Westernized cultures. Focusing on Indonesia, this study delves into how residents adapt their behaviors, especially traditional floor-sitting behavior, to living in the different types of apartments. The study also explores energy consumption and thermal comfort in relation to floor-usage behaviors. We conducted a comprehensive questionnaire survey of more than 3300 respondents in Indonesia, with 1841 Jabodetabek samples used for analysis. The findings indicate that approximately 80% of lower-income apartment residents (Rusunawa) predominantly engaged in floor-sitting behavior and relied on fans for cooling. In contrast, approximately 75% of higher-income apartment residents (condominiums) preferred chair-sitting and used air conditioning (AC). Cluster analysis of three key factors—primary posture, foot covering, and floor covering—revealed four distinct groups. The clusters with a lower preference for floor-sitting exhibited approximately 50% higher annual electricity consumption due to AC usage, whereas the clusters favoring floor-sitting consumed less electricity, relying more on fans. However, despite variations in energy use, over 85% of respondents across all clusters were mostly reported as comfortable, indicating that behavioral adaptations with floor-sitting remain viable in achieving thermal comfort. While an increase in income level changes behaviors and energy use, the results suggest that floor-sitting is a traditional practice that serves as an effective low-energy strategy in hot and humid climates.

Optimizing the thermal environment of a bedroom is desirable for good sleep. In moderate climatic conditions, natural ventilation is a viable method for enhancing the quality of sleep by improving indoor air conditions. This study examined the effects of air temperature and wind speed on sleep quality in naturally ventilated rooms with windows open and closed, during autumn. Thirteen young males in healthy conditions participated in this study. Two adjacent test rooms (for opened and closed conditions) were selected on a university campus, with standardized indoor conditions. Air temperature and wind speed were measured near the height of the participants’ heads. Sleep efficiency and wake after sleep onset (WASO) were calculated using physiological wearable sensors based on heart rate and body movement. The participants completed questionnaires on thermal sensation and comfort before and after sleep. The results showed that the lowest percentage of WASO was observed when the nocturnal mean temperature was 23–24°C with a quadratic regression curve regardless of the window opening conditions. Conversely, subjective sleep satisfaction and WASO did not show any significant differences between the conditions. The results revealed no significant impact of varying thermal and airflow conditions during autumn on thermal/airflow comfort, although significant differences were observed in the thermal/airflow sensation before and after sleep. Thus, these results suggest that natural ventilation through the opening of windows might not affect thermal/airflow comfort, while a nocturnal indoor air temperature of 23–24°C is recommended for good sleep and thermal comfort, regardless of window opening conditions under moderate climate conditions.

Sleep timing is an important output of the circadian system. The COVID-19-mandated social restrictions significantly altered commuting time and sleep duration regionally in Japan. This study aimed to elucidate sleep patterns, especially chronotype and social jetlag (SJL), due to changes in social time pressure through the social restrictions between the Metropolitan and Regional areas in Japan. As part of the Global Chrono Corona Survey 2020 (GCCS), the data were collected during social restrictions (SR), but pre-COVID-19 behaviours were also queried retrospectively. We analyzed a cohort of 729 respondents representing both the Metropolitan and the Regional areas separately for workdays and work-free days. While the areas showed no difference in SJL before SR, the differential decrease was larger in the Metropolitan area during SR, resulting in a significant difference in SJL between the areas. The outdoor light exposure before SR was 30 min longer in the Metropolitan areas than in the Regional; during SR both areas showed similarly low (below 1 h) outdoor light exposures. The variables associated with decreased SJL were the Metropolitan areas, work-from-home, a no-usage alarm clock on workdays, and chronotypes (mid-sleep time on free days corrected for sleep deficit accumulated over the workweek, MSFsc) during SR. The results suggest that relaxed social schedules, as reflected in the increased frequency of work-from-home and reduced alarm clock use, and moving towards earlier MSFsc during SR were linked to decreased SJL and were more prominent in the Metropolitan areas. This study provides insights into sleep patterns and the social time pressure markers, by comparison between residential groups in Japan.

In the tropical climates of Southeast Asia, the growing reliance on air conditioning (AC) for space cooling not only increases household energy consumption but may also diminish the role of culturally rooted adaptive behaviors such as floor-sitting. This study aims to explore the interaction between climatic factors, including regional and indoor climates, and thermally adaptive behaviors in Indonesian apartments, with a focus on floor-sitting. First, a large-scale questionnaire was conducted to analyze these interactions among different regional climates. Second, in-depth indoor climate measurements and a point-in-time questionnaire were conducted among the residents in the hotter regions. In the hotter regions like Jabodetabek (Jakarta metropolitan area) and Surabaya, floor-sitting was primarily conducted without using AC, often alongside fans in low-rise housing. In the cooler region of Bandung, floor-sitting was a common adaptive behavior with window openings in both high-rise and low-rise buildings. The in-depth measurement showed that low-rise buildings using higher thermal mass materials maintained stable indoor conditions for both air and floor temperatures even in the hotter region. The respondents could obtain coolness and remain thermally comfortable through a floor-sitting posture without using AC, especially when air and floor temperatures were both less than 31 °C. These results demonstrated that floor-sitting is a vital behavior that adapts to regional and indoor climatic conditions in the tropics while achieving thermal comfort and relying less on AC devices.

Modern societal factors frequently impede the attainment of good sleep quality by many healthy adults. We investigated the chronotype-specific predictors of changes in subjective sleep quality following the relaxation of social time pressure during COVID-19 pandemic social restrictions in Japan. One thousand two hundred and fifty-two Japanese participants were surveyed during the initial COVID-19 social restrictions. Logistic regression analyses were used to assess changes under modified social time pressure in sleep quality by chronotype group (early, intermediate, or late) from changes in patterns of daily behaviors. During social restrictions, subjective sleep quality deteriorated with delays in sleep timing across all chronotypes. Early and intermediate chronotypes' reduction in sleep quality was associated with decreased sleep duration, whereas improved subjective sleep quality was associated with increased sleep duration and minimal sleep timing delay in the early and intermediate chronotypes. In late chronotypes, improved sleep quality was also associated with longer outdoor light exposure. These findings indicate that the determinants of changes in subjective sleep quality under modified social time pressure are at least partially chronotype-specific. Maintaining sleep timing may universally enhance subjective sleep quality during perturbations of social schedules. Moreover, in late chronotypes, the exposure to daylight may improve sleep quality, regardless of changes in sleep behaviors. These insights may contribute to the development of effective strategies for promoting better sleep quality in modern societies where insufficient sleep is becoming increasingly widespread.