Method and apparatus for measuring autonomic-nervous index and apparatus for detecting biological information

1. An apparatus for measuring an autonomic-nervous index, comprising:

a detection-rate calculating unit that calculates a detection rate representing a ratio of number of interval data generated within a predetermined reference time to a sum of the number of the interval data and number of error data generated within the reference time, the interval data representing a time interval of one cycle of a waveform of at least one of a pulse and a heart rate, the error data representing a content of an error that occurred within the reference time; and

an index calculating unit that calculates an autonomic-nervous index representing an autonomic-nervous activity state, based on the interval data generated within the reference time, when the detection rate is larger than a first threshold.

2. The apparatus according to claim 1 , further comprising a receiving unit that receives the interval data and the error data from a detecting device, the detecting device detecting the waveform of at least one of the pulse and the heart rate of a user and generating the interval data and the error data based on the waveform of the at least one of the pulse and the heart rate, wherein

the detection-rate calculating unit calculates the number of the interval data and the number of the error data received within the reference time and calculates a ratio of calculated number of the interval data to a sum of the calculated number of the interval data and calculated number of the error data as the detection rate.

3. The apparatus according to claim 1 , further comprising:

a receiving unit that receives the waveform of at least one of the pulse and the heart rate of a user detected by a detecting device, the detecting device detecting the waveform of at least one of the pulse and the heart rate of the user; and

an analyzing unit that analyzes the waveform of the at least one of the pulse and the heart rate received by the receiving unit for generating the interval data and the error data.

4. The apparatus according to claim 1 , wherein the error data includes an out-of-range error representing either that the interval data is smaller than a predetermined second threshold or that the interval data is larger than a predetermined third threshold that is larger than the second threshold.

5. The apparatus according to claim 1 , wherein the error data includes a body-movement detected error representing that a body movement of a user is detected when the interval data is generated.

6. The apparatus according to claim 1 , wherein the index calculating unit further compares number of body movements of a user detected within the reference time with a predetermined fourth threshold, and calculates the autonomic-nervous index when the number of the body movements is smaller than the fourth threshold.

7. The apparatus according to claim 1 , wherein the index calculating unit further compares an average value of an amplitude of the waveform of the interval data in the reference time with a predetermined fifth threshold, and calculates the autonomic-nervous index when the average value is larger than the fifth threshold.

8. The apparatus according to claim 1 , wherein the index calculating unit does not calculate the autonomic-nervous index when the detection rate is equal to or smaller than the first threshold.

9. The apparatus according to claim 1 , wherein when the detection rate is equal to or smaller than the first threshold, the index calculating unit calculates a first autonomic-nervous index of a first time period in which the detection rate is equal to or smaller than the first threshold by interpolating between a second autonomic-nervous index of a second time period that is right before the first time period and a third autonomic-nervous index of a third time period that is right after the first time period.

10. The apparatus according to claim 1 , further comprising a sleep-state determining unit that determines a sleep state of a user including a rapid-eye-movement sleep state, a light sleep state, and a deep sleep, based on a calculated autonomic-nervous index.

11. The apparatus according to claim 10 , wherein when the detection rate is equal to or smaller than the first threshold, the sleep-state determining unit determines a first sleep state of a first time period in which the detection rate is equal to or smaller than the first threshold by interpolating between a second sleep state of a second time period that is right before the first time period and a third sleep state of a third time period that is right after the first time period.

12. The apparatus according to claim 11 , wherein the sleep-state determining unit compares the first time period with a predetermined sixth threshold, and determines a fourth sleep state of a fourth time period that is obtained by removing predetermined time periods from both sides of the first time period as the light sleep state when the first time period is larger than the sixth time period.

13. A method of measuring an autonomic-nervous index, comprising:

calculating, using a processor, a detection rate representing a ratio of number of interval data generated within a predetermined reference time to a sum of the number of the interval data and number of error data generated within the reference time, the interval data representing a time interval of one cycle of a waveform of at least one of a pulse and a heart rate, the error data representing a content of an error that occurred within the reference time; and

calculating, using the processor, including

comparing the detection rate with a predetermined first threshold, and

calculating, when the detection rate is larger than the first threshold, an autonomic-nervous index representing an autonomic-nervous activity state, based on the interval data generated within the reference time.

14. A detecting device configured to communicate with an apparatus that measures an autonomic-nervous index representing an autonomic-nerve activity state, the detecting device comprising:

a detecting unit that detects a waveform of at least one of a pulse and a heart rate of a user;

an analyzing unit that analyzes the at least one of the pulse and the heart rate of the user detected by the detecting unit, and generates an interval data representing a time interval of one cycle of the waveform of the at least one of the pulse and the heart rate and an error data representing a content of an error occurred when the interval data is generated; and

a transmission unit that transmits the interval data and the error data to the apparatus.