Method, system and device for sleep stage determination using frontal electrodes
View Patent ↗The described embodiments relate generally to methods, systems and devices for sleep stage determination using frontal electrodes. Certain embodiments relate to a system for sleep stage determination comprising a sensing unit and a processing unit. The sensing unit is positioned over a forehead area of a patient and has first, second and third electrodes for positioning at locations on or adjacent the forehead area for detecting electrical potentials of a human head. The processing unit is coupled to the sensing unit for receiving biological signals corresponding to the detected electrical potentials and processing the biological signals to determine a sleep stage of the patient. The processing of the biological signals is based on a plurality of rules.
1. A method of sleep stage determination, comprising:
receiving electrical potentials corresponding to biological signals from an electrode assembly positioned over a head of a patient;
processing the biological signals to determine EEG signals, EOG signals and EMG signals;
calculating, with a processor, a pre-score based on the EEG signals, the EOG signals and the EMG signals and a plurality of rules;
using said processor for determining based on said plurality of rules and said pre-score whether the sleep stage can be categorized by the pre-score;
checking whether a sleep stage has been categorized based on said pre-score using said processor; and
when said checking step determines that the sleep stage could not be categorized based on said pre-score, determining the sleep stage based on at least one epoch.
2. The method of claim 1 , wherein the rules are based on empirically derived correlations of EEG, EOG and EMG signal activity with one or more stages of sleep.
3. The method of claim 1 , wherein the electrode assembly comprises first, second and third electrodes positioned at locations on or adjacent the forehead area, the first electrode being positioned adjacent a nasion area of the head and the second and third electrodes being positioned over respective laterally opposed forehead areas.
4. The method of claim 3 , wherein the second and third electrodes are positioned above and laterally beyond respective Fp 1 and Fp 2 positions.
5. The method of claim 1 , further comprising, prior to the step of receiving, positioning a sensing unit comprising the frontal electrode assembly over the forehead area, the sensing unit being configured to sense electrical potentials corresponding to the biological signals.
6. The method of claim 1 , wherein in said determining the sleep stage based on at least one epoch step, the sleep stage is determined on an epoch by epoch basis.
7. The method of claim 6 , wherein for an epoch, the step of determining includes evaluating the EEG signals, the EOG signals and the EMG signals received during the epoch according to the plurality of rules and assigning a sleep stage categorization to the epoch.
8. The method of claim 7 , wherein the step of determining includes evaluating the EEG signals, the EOG signals and the EMG signals received during a plurality of epochs according to the plurality of rules and assigning a sleep stage categorization to the epoch.
9. The method of claim 7 , wherein the step of determining is based on previous undecided epochs and last determined epochs and the plurality of rules.
10. The method of claim 1 , further comprising receiving further electrical potentials corresponding to body movement of the patient, wherein the determining is also based on the further electrical potentials.
11. The method of claim 10 , further comprising positioning one or more body movement sensors in relation to a body of the patient away from the head to provide the further electrical potentials.
12. The method of claim 11 , wherein the one or more sensors comprise one or more accelerometers.
13. The method of claim 11 , wherein the one or more sensors comprise one or more electromyographic sensors.