The Onreiyoku: Japan's Ancient Hot-Cold Contrast Bathing Tradition

The Onreiyoku, a natural bathing method, has been practiced in Japan since the early Showa period. While its precise origins are debated, Japan has a long-standing cultural tradition of "Mizugori"—purifying the mind and body with water. This practice involved cold water bathing for health promotion and spiritual discipline.

During the Edo period, it became customary in public bathhouses (sento) to alternate between hot baths and cold plunges, a practice known as "Yuagari Mizuburo." Today, saunas, which originated in Northern Europe, are common in bathing facilities. However, we advocate for promoting The Onreiyoku, a bathing method inherited from ancient Japan.

Optimal Temperatures and Bathing Duration

Nihon Onreiyoku Association recommends alternating between hot water (43°C [109.4°F] or higher) and cold water (19°C [66.2°F] or lower) for an effective Onreiyoku experience. We suggest repeating this cycle, considered one set, for a total of 5 to 10 sets.

The bathing duration is flexible. Generally, it's recommended to immerse yourself in hot water for 1 to 3 minutes and cold water for 1 to 2 minutes. However, please find a comfortable duration that suits your mood, physical condition, and water temperature on any given day. Combining Onreiyoku with saunas, hot springs, or open-air bathing (Gaikiyoku) is also recommended. Explore the ways to enjoy Onreiyoku that best suit you.

Experiencing Water on Your Skin

Bathing facilities offer diverse water textures, varying in temperature, composition, and feel. The benefits of hot springs, natural spring water, natural underground water, and soft water are extensive, and the size and depth of the bathtub also influence how your body warms up. Discovering various ways to enjoy the benefits of each bathing facility is one of Onreiyoku's greatest pleasures.

Always Conclude Onreiyoku with Cold Water

Concluding Onreiyoku with a cold plunge helps "trap" the heat within your body. When peripheral blood vessels constrict in cold water, it's believed to prevent the heat gained during bathing from escaping, making you less susceptible to feeling cold afterward and allowing your body to retain warmth for longer.

Facilities and Environment

Ideally, Onreiyoku is practiced in bathing facilities equipped with separate hot and cold baths. However, it can also be performed at home by combining a bathtub with a cold shower.

A Different Enjoyment from Saunas

While saunas are sometimes referred to as "hot-cold alternating baths," the Onreiyoku we advocate is a bathing method of alternating between hot water and cold water. In contrast to the term "Totonou" often used by sauna enthusiasts, Nihon Onreiyoku Association describes the sensation derived from Onreiyoku as "Shiagaru" (finished or complete). This difference in sensation distinguishes the quality of the experience between the two. Conceptually, we view saunas as "taking out" (e.g., sweating out impurities) and Onreiyoku as "putting in" (e.g., infusing the body with beneficial elements). While saunas offer the "refreshing feeling" of sweating, Onreiyoku emphasizes "putting good things into the body."

Take Your Time and Be Gentle with Yourself

It's crucial to enjoy The Onreiyoku comfortably and without overexertion, incorporating breaks or open-air bathing as needed. This bathing method is adaptable to individual preferences, making it accessible for beginners or those who are not accustomed to cold plunges, and it can be a valuable tool for health management. When practicing, it's essential to consult with your physical condition and avoid overexertion. If you have pre-existing conditions such as heart disease or high blood pressure, we highly recommend consulting a doctor beforehand. (Absolutely refrain from Onreiyoku if you are intoxicated or have recently consumed alcohol.)

Relaxation and Improved Blood Circulation

Immersing yourself in hot water dilates blood vessels, promoting the dominance of the parasympathetic nervous system, which induces relaxation. Conversely, entering cold water constricts blood vessels, stimulating the sympathetic nervous system, which activates the body. By repeatedly subjecting the body to these hot and cold stimuli, it's believed that the autonomic nervous system can switch more smoothly, leading to better balance. This is expected to alleviate autonomic nervous system dysfunctions. Furthermore, the repeated expansion and contraction of blood vessels enhance blood flow like a pump, particularly improving circulation in the extremities.

Fatigue Recovery Hailed by Professional Athletes

Onreiyoku is effective for post-exercise recovery. Numerous studies have shown its efficacy in reducing post-exercise muscle soreness and suppressing muscle strength decline compared to passive rest. Additionally, improved blood circulation is thought to facilitate the expulsion of fatigue-inducing substances, contributing to overall fatigue reduction. University sports medicine departments, among others, have acknowledged its effectiveness in managing athletes' physical condition. Currently, professional sports teams both domestically and internationally are actively incorporating Onreiyoku for athlete conditioning.

Pore Cleansing

Engaging in Onreiyoku causes the pores across the entire body to repeatedly open and close, or contract. As a result, sebum buildup and old dead skin cells that cannot be removed by regular soap are thoroughly cleared away.

Skin Beautification Effects

Through Onreiyoku, blood vessels repeatedly expand and contract. This improves blood circulation, ensuring that nutrients and oxygen are properly delivered to skin cells, normalizing skin metabolism, and thus promoting healthier and more beautiful skin.

Improvement of Cold Sensitivity

The repeated contraction and expansion of blood vessels are believed to enhance the body's temperature regulation function. This allows warm blood to be efficiently delivered to the extremities even in cold environments, contributing to the improvement of cold sensitivity (poor circulation).

Weight Management Benefits

When the body attempts to adapt to sudden temperature changes, it expends more energy to maintain body temperature, which activates metabolism. Additionally, cold stimulation invigorates "brown fat cells," which are fat-burning cells, thereby promoting fat combustion. Improved blood circulation also facilitates the expulsion of excess bodily fluid (edema), which can lead to a more toned appearance.

Enhanced Sleep Quality

A decrease in body temperature is crucial for good sleep. Alternating between hot and cold water temporarily raises body temperature, then lowers it, sending a sleep signal to the brain and promoting sleep onset. Furthermore, hot and cold stimuli encourage serotonin secretion, which converts to melatonin at night, making it easier to sleep. (It's advisable to finish Onreiyoku at least two hours before bedtime, as immediate pre-sleep practice might have an awakening effect and disrupt sleep.)

Stress Reduction and Invigoration

When the autonomic nervous system is balanced through Onreiyoku, the body becomes less prone to overreacting to stress. The intense stimuli from hot and cold water are thought to promote the secretion of pleasure-inducing substances like endorphins in the brain, leading to feelings of happiness and invigoration.

Please note that the effects of Onreiyoku vary individually and are based on personal experiences derived from typical bathing practices. If you have pre-existing conditions such as heart disease or high blood pressure, always consult a doctor and obtain their permission before engaging in Onreiyoku.