Sleep state monitoring system based on pulse wave measurement

A sleep state monitoring system comprising:

• a first sensor that is one of a pressure sensor and an optical sensor, the first sensor of the pressure sensor being provided via a skin on a blood vessel of an aortic portion of a human body and detecting a change in pressure of a pulse wave propagating through the blood vessel to measure a voltage value as a first voltage value of arterial pressure, the first sensor of the optical sensor being provided via the skin on the blood vessel of the aortic portion of the human body and detecting a pulse wave propagating through the blood vessel to measure a voltage value as a first voltage value of blood vessel pressure;
• a second sensor that is an optical sensor, the second sensor being provided via a skin on a peripheral blood vessel of the human body and detecting 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;
• and
• a controller configured to determine a sleep state of the human body, based on the first voltage value and the second voltage value,
• wherein the controller
• (A) determines that the human body is in non-wakefulness when the first voltage value increase and decrease within a first increase and decrease amount and the second voltage value increase and decrease within a second increase and decrease amount for a predetermined time interval, and
• (B) determines that the human body is in wakefulness when the first voltage value increases by an amount of increase equal or larger than a predetermined first threshold and the second voltage value decreases by an amount of decrease equal to or smaller than a predetermined second threshold for the time interval.