Self-monitoring by wearable biosensors is thought to be a form of biofeedback during daily activity. Analysis of heart rate variability (HRV) from ambulatory electrocardiogram or pulse wave is widely used for this purpose, i.e., the self-control of autonomic functions under various conditions such as sleep, relaxation, exercise, and stress. However, there is a question whether the principle of autonomic assessment by HRV that was developed on short-term HRV under controlled conditions can be directly applied to HRV under uncontrolled daylily activities. Many recent studies have reported results that do not support this. More attention needs to be paid to the application, analysis, and interpretation of HRV in daily life. Conversely, the long-term monitoring of HRV during daily life also has advantages over short-term HRV. That is the evaluation of the reflex autonomic functions using the heart rate responses to accidentally occurring biological phenomena during daily life, such as ventricular ectopic beats and sleep apnea episode. This paper describes the limitations and usefulness of long-term monitoring of biological functions, focusing on heart rate and HRV.

  The history of neurofeedback goes back to the 1960s. Although it has made remarkable progress overseas, it is very rarely used as a medical treatment in Japan. Neurofeedback generally refers to biofeedback using electroencephalograms. In a broad sense, it is biofeedback of various brain activities (DC potentials and cerebral blood flow). Although recent advances in computer technology and equipment have enabled highly complex feedback, EEG feedback using 1-2 electrodes is common. Unlike normal biofeedback, this technology feeds information from the brain back to the brain function itself, not to consciousness. It allows the brain to learn certain response patterns autonomously. The goal is to cause functional expansion of the brain by feeding back information that the person cannot recognize. Since 2007, our hospital has applied neurofeedback as a psychosomatic treatment to various pathological conditions. The progress of neurofeedback has been remarkable, and personal experience does not provide a full picture. Based on my experience, I introduce the effects, limitations and future prospects of neurofeedback.