Japanese chilled tenugui offers a low‑tech solution for better sleep in extreme heat

As temperatures rise above 30 °C, many people struggle to fall asleep and stay comfortable at night. In Japan, where humid summers are common and electricity costs are high, a traditional cotton towel called a tenugui is being frozen for about thirty minutes and then placed on the neck, forehead, wrists or temples before bedtime. The chilled fabric cools the skin’s surface veins, helping the body lower its core temperature and facilitating deeper sleep without the need for air‑conditioning.

Scientific studies cited in PubMed Central indicate that head‑cooling can improve sleep parameters for heat‑sensitive individuals. The method is simple, low‑cost, and can be combined with other Japanese practices such as sleeping on a low futon, using a bamboo sudare screen, or creating cross‑ventilation with opposite windows.

Beyond the physical discomfort, the heatwave also exacerbates mental‑health challenges. Reports from the National Institute of Mental Health and the Cleveland Clinic describe a summer form of seasonal affective disorder, characterized by irritability, insomnia and fatigue, especially for introverted or highly sensitive people. Personal accounts, such as a German journalist’s description of “summer‑grinch” feelings, highlight the social pressure to stay outdoors during long, bright evenings, which can increase stress and disrupt circadian rhythms.

Together, these insights suggest that low‑tech cooling tools like a frozen tenugui, combined with mindful routines and attention to light exposure, can help mitigate both the physiological and psychological impacts of extreme summer heat.