BrainSleep Inc. (Head office: Chiyoda-ku, Tokyo; Representative Director: Atsushi Hirota; hereinafter "BrainSleep") conducted a one-year sleep data analysis (hereinafter "this analysis") in collaboration with the Stanford University Sleep & Circadian Neurobiology Laboratory (SCNL) with the aim of breaking the relationship between sleep and seasons.This analysis utilized one year's worth of sleep data from users of "BrainSleep Coin," a sleep measurement tool provided by BrainSleep, to analyze how sleep changes monthly. The results showed that July had the most significant change in sleep quality over the year, including a reduction in sleep duration and the duration of deep sleep, which is considered the most important part of sleep. Background According to a 2021 survey by the Organization for Economic Cooperation and Development (OECD), Japan has the shortest sleep duration in the world at 7 hours and 22 minutes, revealing a chronic lack of sleep. Furthermore, the increasing heat each year accelerates physical fatigue and also has a serious impact on sleep quality, such as difficulty falling asleep and increased awakenings during the night. Prior research conducted before this analysis reported a decrease in sleep duration and efficiency during summer compared to winter, suggesting that seasonal changes may affect sleep. Therefore, we collaboratively analyzed the relationship between sleep and seasonal changes as a first step to find a solution.This analysis utilized user data from "BrainSleep Coin," a sleep measurement tool developed and launched by BrainSleep in October 2022 as a product/service to quantify one's sleep with the aim of improving sleep quality. * 1 https://doi.org/10.11239/jsmbe.Annual60.122_1 Overview ＜Data＞365,722 nights of data (7,350 individuals) obtained from January 1 to December 31, 2024＜Analysis Method＞The sleep score, sleep duration, and deep sleep duration measured by "BrainSleep Coin" were analyzed. For sleep score, the monthly average was calculated and compared to the annual average for each user. For sleep duration and deep sleep duration, the monthly average was calculated and compared to the annual average, focusing on users with a difference of 12 points or more (top 20%) in their annual sleep score. The report points out months that showed an intentional difference compared to July. Results This analysis revealed that July had the lowest sleep score, and that "reduced sleep duration" and "decreased sleep quality" were the main factors for this decline.The main reason for the reduced sleep duration is strongly influenced by the extended daylight hours. As sunrise occurs earlier, people tend to get out of bed earlier, and the secretion of melatonin, the sleep hormone, also advances, making it difficult to fall asleep smoothly when trying to go to bed. Furthermore, indicators of decreased sleep quality such as "reduced deep sleep duration" and "delayed time to reach deep sleep" can be attributed to environmental factors such as indoor temperature and humidity affected by outside temperatures, which prevent the core body temperature from dropping smoothly.In summer, it is effective to take measures such as ensuring sufficient sleep duration regardless of daylight hours, taking baths correctly (e.g., bathing 90 minutes before sleep) to facilitate a drop in core body temperature, and using bedding to maintain appropriate bed temperature and humidity. Result ① Sleep score tends to decrease in summer Among the summer months, July showed the lowest sleep score, with a difference of approximately 1.7 points compared to December, which had the highest sleep score. This indicates a conscious decrease in sleep score during summer. Result ② Sleep duration tends to shorten in summer Sleep duration is shorter in summer, with July, the shortest month, showing a consciously shorter duration of approximately 12 minutes compared to December. Result ③ In summer, deep sleep decreases and the time to reach deep sleep tends to be delayed. In summer, the duration of deep sleep is shorter, with July, the shortest month, showing a consciously shorter duration of approximately 7.5 minutes compared to December. Furthermore, a delay in the time to reach deep sleep after falling asleep was also observed. Comment from BrainSleep Chief Research Advisor, Seiji Nishino It is well known that our lives and sleep change with the seasons. Chinese and Japanese proverbs such as "Spring sleep knows no dawn" and "Autumn nights are long" are typical examples.Therefore, we analyzed seasonal sleep fluctuations over one year using data from over 7,000 users of "BrainSleep Coin," a sleep measurement tool provided by BrainSleep. The results showed that in Japan's humid summer, not only did sleep duration shorten, but sleep quality also tended to decline, which became an issue. On the other hand, in autumn, as the Japanese proverb suggests, sleep tended to recover with the decrease in daylight hours.For spring, although there was a tendency for more deep sleep, we had already noticed signs of sleep deterioration in summer.From these results, it is considered important to ensure comfortable conditions during the hot and humid summer, and for this purpose, the use of bedding and pillows made of materials that do not trap heat and moisture is effective. Seiji Nishino Professor, Department of Psychiatry, Stanford University School of MedicineDirector, Stanford University Sleep & Circadian Neurobiology LaboratoryFounder and Chief Research Advisor, BrainSleep Inc.Physician, Doctor of MedicineCertified Qualifications: Designated Physician for Mental Health, Japanese Society of Sleep Research Certified Sleep Physician, Industrial Physician What is the Sleep Measurement Tool "BrainSleep Coin"? A sleep measurement tool that converts sleep into value, equipped with a proprietary measurement algorithm developed based on data researched by third parties through sleep research. It enables more personalized analysis based on human movement and supports improved sleep quality by proposing a positive cycle where sleep scores are converted into coins, leading to improved sleep habits.1. Measure: Developed based on sleep researchIt incorporates a proprietary algorithm developed based on sleep research and applies technologies used in sleep research.2. Improve: Personalized adviceIt identifies problems based on your sleep condition and provides advice to improve your sleep.It offers improvement suggestions tailored to your daily sleep condition, supporting better sleep.3. Sleep: Earn coins every time you sleepYour sleep condition and good sleep habits are converted into Sleep Coins. Accumulated Sleep Coins can be exchanged for discount coupons for BrainSleep products or for in-app music purchases. ＜Product Details＞Product Name: BrainSleep CoinPrice: Free app, device 8,800 yen (tax included)URL: https://brain-sleep.com/products/coin
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