「寝る前のスマホOK！？」「＋30分」で適切な睡眠時間を把握 寝不足解消は15～20分のパワーナップで（2026年05月29日）

(Broadcast May 28, 2026) "What's the deal?" - Unraveling intriguing questions and answering the "why?" behind news stories. On the 26th, the Ministry of Health, Labour and Welfare announced that it will add "sleep disorders" to the list of medical specialties displayed by medical institutions, such as "internal medicine" and "pediatrics." The Ministry of Health, Labour and Welfare states that prolonged sleep deprivation increases the risk of developing conditions such as high blood pressure and heart disease, and hopes that adding "sleep disorders" will lead to earlier detection and treatment of these diseases. The May 28th episode of "What's the deal?" is titled "Is using your smartphone before bed bad? Surprising new common sense about sleep." According to a survey on sleep and work conducted by Mynavi, 26.9% of 600 full-time employees aged 20-50 reported sleeping "less than 6 hours," or about one in four. Approximately 30% reported experiencing sleep deprivation "5-7 days a week." According to Professor Masashi Yanagisawa of the University of Tsukuba, who conducts world-leading sleep research, there is a way to determine your appropriate sleep duration. First, try sleeping 30 minutes longer than usual for 3-4 days. As a result, those who were previously sleep-deprived may experience effects such as reduced daytime sleepiness, improved morning wakefulness, and increased concentration. If you still feel sleep-deprived, try sleeping another 15-30 minutes longer, repeating this process until daytime sleepiness disappears—this is considered your "appropriate sleep duration." For those who find it difficult to add 30 minutes due to work, school, and family commitments, a method called "power nap" is recommended. At the "Nescafe Sleep Cafe" in Harajuku, Tokyo, a power nap is a short nap of about 15-20 minutes, and this cafe offers a "coffee nap" experience where you drink coffee before your nap. According to Professor Yanagisawa, drinking coffee before a nap allows the caffeine to kick in just as you wake up, resulting in a refreshing awakening. He emphasizes that this is merely a temporary measure to compensate for lost sleep. Similarly, another common image of things to avoid before bed is "don't use your smartphone." Professor Yanagisawa states that modern smartphones automatically dim screens based on ambient light and have settings to reduce the effects of blue light, so using your phone before bed is fine depending on how you use it; the key is what you look at. He suggests that movies are acceptable content to watch before bed. Professor Yanagisawa explains that short videos offer a constant stream of new stimuli as you swipe to see what's next. Also, he advises against using chat or social media, as these are interactive and require constant interaction. This can keep the brain awake and prevent sleepiness, so he says they should be "absolutely avoided." On the other hand, he says that movies that can be watched casually are fine, as long as they aren't overly stimulating or exciting. However, some people find it difficult to relax while using their smartphones, so it's important to find a method that suits you. And as we head into the rainy season, temperatures will rise, and there will likely be some uncomfortable nights. There are effective ways to get good sleep during such times. It's said that leaving the air conditioner on while you sleep is better for sleep quality than setting a timer to turn it off. The room temperature rises after the air conditioner turns off, making it uncomfortable to sleep, so keeping it on helps maintain a comfortable room temperature. Another important point is to use an extra blanket or towel. If you don't use anything because it's hot, your body won't be able to regulate its temperature while you sleep.