EOG-based sleep staging method, computer program product with stored programs, computer readable medium with stored programs, and electronic apparatuses

An electrooculograppy(EOG)-based sleep staging method for a processor, the method comprising:

• a preparing step by a polysomnography, reading to-be-test data, wherein the to-be-test data comprises an EOG signal having a variation depending on time of the EOG signal generated by a user during a sleep process;
• an acquiring step by the processor, acquiring a plurality of eye movement characteristics according to the variation of the EOG signal during an epoch comprising a plurality of segments, wherein the eye movement characteristics comprise an eye movement ratio, a blink count, a low-frequency power ratio, a high-frequency power ratio, an alpha ratio, a spindle ratio, a delta ratio and a mean amplitude of the EOG signal, wherein the eye movement ratio is a ratio of a number of eye moving segments to a number of the segments in the epoch, the low-frequency power ratio is a ratio of a power of 0-4 hertz of a frequency-domain signal to 0-30 hertz of the frequency-domain signal in the epoch, the high-frequency power ratio is a ratio of a power of 13-22 hertz of the frequency-domain signal to 0-30 hertz of the frequency-domain signal in the epoch, the alpha ratio is a ratio of a number of alpha segments to the number of the segments in the epoch, the spindle ratio is a ratio of a number of spindle segments to the number of the segments in the epoch, and the delta ratio is a ratio of a number of slow-wave-sleep segments to the number of the segments in the epoch;
• a determining step by the processor, determining that a sleep state of the epoch is a WAKE stage, a rapid eye movement (REM) stage, a S1 stage, a S2 stage or a slow wave sleep (SWS) stage according to the plurality of eye movement characteristics by a decision tree comprising:
• a first node, determining whether the eye movement ratio is greater than a first threshold, and performing a second node if yes, and performing a third node if not;
• the second node, determining whether the delta ratio is greater than a second threshold and the high-frequency power ratio is less than a third threshold, and determining that the sleep state is the SWS stage if yes, and determining that the sleep state is the S2 stage if not;
• the third node, determining whether the eye movement ratio is greater than a fourth threshold, and performing a fourth node if yes, and performing a fifth node if not, wherein the fourth threshold is less than the first threshold;
• the fourth node, determining whether the spindle ratio is greater than a fifth threshold and the low-frequency power ratio is less than a sixth threshold, and performing a sixth node if yes, and determining that the sleep state is the REM stage if not;
• the fifth node, determining whether the alpha ratio is greater than a seventh threshold and the blink count is greater than an eighth threshold, and determining that the sleep state is the WAKE stage if yes, and performing a seventh node if not;
• the sixth node, determining whether the mean amplitude of the EOG signal is greater than a ninth threshold, and determining that the sleep state is the S1 stage if yes, and determining that the sleep state is the S2 stage if not;
• and
• the seventh node, determining whether the alpha ratio is greater than a tenth threshold, and determining that the sleep state is the S2 stage if yes, and determining that the sleep state is the REM stage if not, wherein the tenth threshold is less than the seventh threshold;
• and
• applying a plurality of smoothing rules to the EOG signal, wherein the smoothing rules comprise:
• each REM stage before a very first appearance of the S2 stage is replaced with the S1 stage;
• a sequence of the WAKE stage, the REM stage, and the S2 stage is replaced with a sequence of the WAKE stage, the S1 stage, and the S2 stage;
• a sequence of the S1 stage, the REM stage, and the S2 stage is replaced with a sequence of the S1 stage, the S1 stage, and the S2 stage;
• a sequence of the S2 stage, the S1 stage, and the S2 stage is replaced with a sequence of the S2 stage, the S2 stage, and the S2 stage;
• a sequence of the S2 stage, the SWS stage, and the S2 stage is replaced with a sequence of the S2 stage, the S2 stage, and the S2 stage;
• a sequence of the S2 stage, the REM stage, and the S2 stage is replaced with a sequence of the S2 stage, the S2 stage, and the S2 stage;
• a sequence of the SWS stage, the S2 stage, and the SWS stage is replaced with a sequence of the SWS stage, the SWS stage, and the SWS stage;
• a sequence of the REM stage, the WAKE stage, and the REM stage is replaced with a sequence of the REM stage, the REM stage, and the REM stage;
• a sequence of the REM stage, the S1 stage, and the REM stage is replaced with a sequence of the REM stage, the REM stage, and the REM stage;
• and
• a sequence of the REM stage, the S2 stage, and the REM stage is replaced with a sequence of the REM stage, the REM stage, and the REM stage.