Patent US8755879 Consumer Sleep Technology

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Patent US8755879

Issued 2014-06-17

Sleep Tracking And Waking Optimization System And Method Therefor

Analog electrical and pressure data obtained by an EEG/pressure sensor matrix from the subject are sent to a signal processing module that derives digital EEG data from the electrical signal and pressure data without using sensors attached to a subject's head. The pressure data are used as a secondary signal to measure the physical orientation of the subject's head. The physical orientation is used to transform the derived EEG signal to a known coordinate axis (the orientation of the subject's head) to obtain useful, consistent, and accurate EEG data. The EEG may be used to determine a sleep state of a subject and to awaken the subject while in a particular state.

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4 Independent Claims

1. A system for acquiring an EEG signal suitable for use in electroencephalography from a subject, the system comprising: a sensor matrix comprising a plurality of EEG electrodes configured to receive electrical signals from the brain of the subject and a plurality of pressure sensors configured to receive pressure signals indicative of the placement of the head of the subject on the sensor matrix; a processing control unit configured to perform operations comprising: obtaining EEG electrode data from the electrical signals received by the sensor matrix; determining a scalar EEG voltage for each EEG electrode; obtaining pressure data from the pressure signals received by the sensor matrix; determining a pressure normal unit vector for each EEG electrode from the pressure data; summing the product of the pressure normal unit vector and the scalar EEG voltage for each EEG electrode to obtain a relative mean EEG vector; and obtaining an absolute scalar EEG vector from a dot product of a unit orientation vector and the relative mean EEG vector.
6. A method for acquiring an EEG signal suitable for use in electroencephalography from a subject, the method comprising: receiving by a processor EEG electrode data from a plurality of EEG electrodes residing on a sensor matrix, wherein EEG electrode data are obtained from electrical signals from the brain of the subject; determining by the processor a scalar EEG voltage for each EEG electrode; receiving by the processor pressure data from a plurality of pressure sensors residing on the sensor matrix, wherein the pressure data are obtained from pressure signals indicative of the placement of the head of the subject on the sensor matrix; determining by the processor a pressure normal unit vector for each EEG electrode from the pressure data; summing by the processor the product of the pressure normal unit vector and the scalar EEG voltage for each EEG electrode to obtain a relative mean EEG vector; and obtaining by the processor an absolute scalar EEG vector from a dot product of a unit orientation vector and the relative mean EEG vector.
11. A system for awakening a subject, the system comprising: a pillow comprising: a sensor matrix, wherein the sensor matrix comprises a plurality of EEG electrodes configured to receive electrical signals from the brain of the subject and a plurality of pressure sensors configured to receive pressure signals indicative of the placement of the head of the subject on the sensor matrix; a memory for receiving EEG electrode data derived from the electrical signals and receiving pressure data derived from the pressure signals; and an alerting device; and a processing control unit configured to perform operations comprising: obtaining the EEG electrode data from the memory; determining a scalar EEG voltage for each EEG electrode; obtaining pressure data from the memory; determining a pressure normal unit vector for each EEG electrode from the pressure data; summing the product of the pressure normal unit vector and the scalar EEG voltage for each EEG electrode to obtain a relative mean EEG vector; obtaining an absolute scalar EEG vector from a dot product of a unit orientation vector and the relative mean EEG vector; determining a sleep state of the subject from the absolute scalar EEG vector; and issuing a command to power on the alerting device to awaken the subject while the subject is in or is approaching a light sleep state.
20. A method for awakening a subject, the method comprising: receiving by a processor EEG electrode data from a plurality of EEG electrodes residing on a sensor matrix, wherein EEG electrode data are obtained from electrical signals from the brain of the subject; determining by the processor a scalar EEG voltage for each EEG electrode; receiving by the processor pressure data from a plurality of pressure sensors residing on the sensor matrix, wherein the pressure data are obtained from pressure signals indicative of the placement of the head of the subject on the sensor matrix; determining by the processor a pressure normal unit vector for each EEG electrode from the pressure data; summing by the processor the product of the pressure normal unit vector and the scalar EEG voltage for each EEG electrode to obtain a relative mean EEG vector; and obtaining by the processor an absolute scalar EEG vector from a dot product of a unit orientation vector and the relative mean EEG vector determining a sleep state of the subject from the absolute scalar EEG vector; and issuing a command to power on an alerting device to awaken the subject while the subject is in or is approaching a light sleep state.