Patent ID: 7699785
Filing Date: 2010-04-20
Classification: A61B,G08B

Abstract:
1. A method for determining sleep stages of an examinee, the method comprising: detecting signals of the examinee with a biosignal detector that is non-restraint, non-contact and non-invasive to the examinee; calculating a signal strength with a signal strength calculator obtained as a reciprocal of a coefficient obtained by gain-controlling the detected signals, the gain being set so that an amplitude of the output signals decreases when a peak value of the detected signals exceeds an upper limit threshold and the amplitude of the output signals increases when the peak value of the detected signals is below a lower limit threshold; calculating a signal strength variance value that indicates variation of the calculated signal strength; and determining a sleep stage by using the signal strength variance value or a value derived from the signal strength variance value as an indicator value.