What is "totonoi"?
Oct 7, 2023
Abnormal sensation caused by rapid environmental changes
The time lag between nerves and blood substances is the key
When exposed to extreme environments like a sauna or cold bath, the human body needs to adapt. There are two main methods for this adaptation. First, there is regulation by the autonomic nervous system. This is based on electrical activity and can respond rapidly. However, because the autonomic nervous system relies on instructions from the brain one by one, it is not suitable for efficiently synchronizing the entire body. That is where hormones (substances in the blood) play an active role. Hormones are secreted in response to nerve activation and transported throughout the body via the bloodstream. This allows the entire body to align and adapt to environmental changes. Although hormones do not respond as quickly as nerves, they excel at synchronizing the entire body.
Entering the sauna and cold bath activates the sympathetic nervous system, and the subsequent rest significantly activates the parasympathetic nervous system, leading to deep relaxation.
When the sympathetic nervous system is activated, hormones (excitatory substances) such as adrenaline and noradrenaline are secreted. These hormones have a relatively slower response than nerves, and their effect is halved in about 2 minutes.
For two minutes immediately after exiting the cold bath, the nerves quickly switch to the parasympathetic nervous system, but excitatory substances remain in the blood, creating a state where you are deeply relaxed yet your mind is clear and sharp—in a sense, close to an athlete's 'zone'.
We believe this is one reason for the sensation of 'totonou'.
'totonou' and the Autonomic Nervous System
Everyone has their own way to totonou
When measuring the state of the autonomic nervous system for each Set of the sauna, we find that there are major individual differences. For some people, going up to 4 Sets can actually lower autonomic function, resulting in the opposite of the desired effect.
The body changes depending on the individual or their physical condition on that day. Surprisingly, it is difficult to perceive one's own state by oneself. This is similar to how someone who sees a growing child every day might find it hard to notice their growth, while someone who meets them occasionally notices it easily; because we live with ourselves every day, changes are hard to detect.
In other words, this means that the way you take a sauna also needs to be adjusted individually or according to your physical condition on that day.
By doing so, you can not only find a way to 'totonou' more deeply, but also prevent harming your health by overdoing it, leading to enjoying the sauna safely.
The Brain Science of 'totonou'
'totonou' is super unique from a brain science perspective, too!
When analyzing 'totonou' using an ultra-high precision electroencephalograph called MEG (Magnetoencephalography), we discovered something surprising.
In the post-sauna 'totonou' state, the brain is deeply relaxed, but not sleepy; instead, the mind is clear, and it can be described as a state where creative ideas are easily generated.