Method and apparatus for monitoring and estimating the awakeness of a person

An apparatus for monitoring and estimating a person's wakefulness and, thereby, drowsiness, comprising

• at least one stationary pressure sensitive means (2, 3, 4) which is adapted to contact at least a portion of said person's (1) body, and to generate an electric signal on its output terminal in response to said person's body movements relative to same,
• a detector/filter circuit (5), connected to the output terminal of said at least one stationary pressure sensitive means (2, 3, 4), and adapted to separate, from said electric signal, signals corresponding to the duration and magnitude of true body movements, to the amplitude of heartbeat-related body movements as a function of rate, and to the amplitude of respiration-related body movements as a function of rate, and output these separated signals on corresponding output terminals,
• a first calculation and comparison circuit (8, 11) which is adapted to receive, on its input terminal, said signal corresponding to true body movements, to calculate the duration and magnitude of the true body movements as well as the time interval between same, and to compare these calculated values with previously calculated corresponding values to determine possible changes,
• a second and a third calculation and comparison circuit (6, 9 and 7, 10, respectively) which are adapted to receive, on their input terminals, said signal corresponding to heartbeat-related and respiration-related body movements, respectively, to calculate the amplitude of every heartbeat-related and every respiration-related body movement, respectively, as well as the time interval between at least two successive heartbeats and respirations, respectively, and to compare these calculated values with previously calculated corresponding values to determine possible changes,
• a correlator (12), connected to the the output terminals of said three calculation and comparison circuits (6, 9;
• 7, 10;
• 8, 11), and adapted to correlate heartbeat-related and respiration-related changes with true body movement changes,
• a threshold detector circuit (13), connected to the output terminal of the correlator (12), and adapted to compare the resulting change with a preset wakefulness threshold, and
• an alarm device (14), connected to the output terminal of the threshold detector circuit (13), and adapted to trigger alarm when the preset threshold is reached as an indication of a reduced degree of wakefulness.