Abstract: A sleep state monitoring system is provided a pressure sensor, an optical sensor, and a controller. The pressure sensor detects a change in pressure of a pulse wave propagating through a blood vessel to measure a voltage value as a first voltage value of arterial pressure, and the optical sensor detects a change in pressure of a pulse wave propagating through the blood vessel by use of an optical signal to measure a voltage value as a second voltage value of a vascular pulse wave signal. The controller determines a sleep state of the human body, based on the first voltage value and the second voltage value.

Abstract: A vessel pulse wave measurement system performs vessel pulse wave measurement using an optical probe circuit provided with an optical probe including a light emitting element and a light receiving element, a drive circuit, and a detection circuit. A measurement device directly and synchronously feeds back an electrical signal from the optical probe to the drive circuit as a drive signal to generate a self-oscillation signal from the detection circuit, and measures the self-oscillation signal as a vessel pulse wave signal. A controller controls an operating point of at least one of the detection circuit and the drive circuit such that the self-oscillation signal substantially reaches a maximum level thereof.

Abstract: A vessel pulse wave measurement system performs vessel pulse wave measurement using an optical probe circuit provided with an optical probe including a light emitting element and a light receiving element, a drive circuit, and a detection circuit. A measurement device directly and synchronously feeds back an electrical signal from the optical probe to the drive circuit as a drive signal to generate a self-oscillation signal from the detection circuit, and measures the self-oscillation signal as a vessel pulse wave signal. A controller controls an operating point of at least one of the detection circuit and the drive circuit such that the self-oscillation signal substantially reaches a maximum level thereof.

Abstract: A vessel pulse wave measurement system performs vessel pulse wave measurement using an optical probe circuit provided with an optical probe including a light emitting element and a light receiving element, a drive circuit, and a detection circuit. A measurement device directly and synchronously feeds back an electrical signal from the optical probe to the drive circuit as a drive signal to generate a self-oscillation signal from the detection circuit, and measures the self-oscillation signal as a vessel pulse wave signal. A controller controls an operating point of at least one of the detection circuit and the drive circuit such that the self-oscillation signal substantially reaches a maximum level thereof.