Daiwa House Industry and Nara Medical University Commence Joint Research on "Living Environments for Quality Sleep" (Newsletter)

Daiwa House Industry Co., Ltd. (Headquarters: Osaka; President: Hirotsugu Otomo; hereinafter "Daiwa House Industry") and Nara Medical University (President: Midori Shima; hereinafter "Nara Medical University") commenced joint research on living environments that achieve quality sleep on April 1, 2026.

This research will medically verify the impact of the living environment on sleep through a randomized controlled trial (※1) involving approximately 200 adults. Daiwa House Industry aims to realize a "living environment that improves sleep quality" based on medical evidence by integrating the evidence obtained from this research with technologies related to high insulation, whole-house air conditioning, soundproofing, and noise reduction.

※1. A clinical research method where subjects are randomly divided into groups, and results are compared based on the presence or absence of intervention with research elements. It is internationally recognized as a highly reliable method for medical evidence.

Ensuring quality sleep is essential for maintaining and promoting health. While the Ministry of Health, Labour and Welfare's "Sleep Guide for Health Promotion 2023" recommends at least 6 hours of sleep for adults, the proportion of people with an average daily sleep time of less than 6 hours accounts for over 40% among men in their 30s to 50s and women in their 40s to 50s. Ensuring sufficient sleep for each individual has become a significant health challenge for the nation.

Furthermore, previous medical research has shown that sleep environment factors such as temperature, light, and sound contribute to sleep quality, and the same guide recommends appropriately adjusting the sleep environment to obtain quality sleep. However, medical knowledge regarding optimal living environments for sleep is not sufficiently accumulated. In particular, there are only a few highly reliable studies based on Japan's climatic conditions and actual living environments. In the housing industry, efforts to verify living environment conditions suitable for health based on a medical framework and apply them to home building have been insufficient, often limited to referencing findings from prior research.

Therefore, Daiwa House Industry and Nara Medical University have decided to commence joint research aimed at developing housing products based on new medical evidence concerning quality sleep. They will explore how housing can enable individuals, even those who find it difficult to secure sufficient sleep due to work or family circumstances, to achieve healthy and high-quality sleep by optimizing their living environment without significantly altering their lifestyle.

Moving forward, both parties will continue to contribute to the realization of enriched living and sustainable societal development by advancing research into homes that promote healthy living.

1. Overview of the Joint Research

This research is jointly conducted by Daiwa House Industry's Comprehensive Technology Research Institute and Professor Keigo Saeki of Nara Medical University. Based on Japan's climatic conditions and actual living environments, it aims to medically verify the impact of living environment factors such as temperature, humidity, illuminance, and sound on sleep and health, and to acquire new evidence contributing to quality sleep.

Period	April 1, 2026 - March 31, 2029
Subjects	Approximately 200 healthy adult men and women aged 20-65 residing in Japan
Content	Research on the impact of living environment (temperature, humidity, illuminance, sound, etc.) on sleep
Method	Medical verification through a randomized controlled trial. Evaluation will be conducted from both objective sleep indicators using wearable devices in actual sleep environments and subjective indicators via questionnaires.

■ About Professor Keigo Saeki

After graduating from Jichi Medical University School of Medicine, he engaged in rural medical care in Soni Village and Totsukawa Village, Nara Prefecture. Currently, he presides over the Department of Epidemiology and Preventive Medicine at Nara Medical University. His specialty is environmental epidemiology. He conducts large-scale cohort studies (※2) on the impact of living environments on health, targeting general residents of Nara Prefecture. His research findings have been featured in guidelines by WHO and the Ministry of Health, Labour and Welfare.

● Key Career Highlights

2017 - Present: Professor, Department of Epidemiology and Preventive Medicine, Nara Medical University

March 2020 - Present: Board Member, Japanese Society for Hygiene

※2. An epidemiological research method that tracks a group with common characteristics (cohort) over a certain period to observe the relationship between factors and outcomes.

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