1. Estimation of Sleep Onset Latency Based on the Blood Pressure Regulatory Reflex Mechanism IEEE JOURNAL OF BIOMEDICAL AND HEALTH INFORMATICS Volume 17, Issue 3, Pages 539-544, May 2013 Da Woon Jung, Su Hwan Hwang, Gih Sung Chung, Yu-Jin Lee, Do-Un Jeong, and Kwang Suk Park 1 Reporter: Jie-Lin Huang

2. Outline Introduction Materials And Methods Results Conclusion Personal Remark 2

3. Introduction (1/2) 3 Sleep onset latency (SOL) provides an objective assessment of sleepiness. Blood pressure (BP) regulatory reflex mechanism using only the electrocardiogram (ECG) and ballistocardiogram (BCG). This strong activation of the arterial baroreflex suggests that it has a marked influence on heart beat interval (HBI) control from the time of sleep onset.

4. Introduction (2/2) 4 We measured the R–R and R–J intervals from the R peak on ECG and the J peak on BCG to represent HBI and systolic blood pressure (SBP).

5. Methods (1/8) 5 Subjects

6. Methods (2/8) 6 Experimental Protocol Because BP is dependent on environmental temperature and humidity, the sleep laboratory was maintained at a constant temperature (24 ± 1 °C)v and humidity (40–50%) during the experiment. Data Recording and Collecting Polysomnography (PSG) and BCG recordings were performed simultaneously using a bed equipped with load cells over an 8-h period

7. Methods (3/8) 7 PSG Recording EEG ： C3-A2 and O2-A1 EOG ： Bilateral EMG ： Chin and anterior tibialis muscles ECG ： Lead II Snoring ： Microphone Blood oxygen saturation

8. Methods (4/8) 8 BCG Recording IA refers to instrumentation amplifier, HPF refers to high-pass filter, MUX refers to multiplexer, and PC refers to personal computer.

9. Methods (5/8) 9 Time Series Analysis We obtained the time interval between successive R peaks of ECG, called the R–R interval, and the time interval between the R peak on the ECG and the J peak on the BCG, called the R–J interval.

10. Methods (6/8) 10

11. Methods (7/8) 11 SOL Estimation The arterial baroreflex would have a marked influence on the HBI control with the onset of sleep. We expected to find a negative correlation between fluctuations of the R–J interval and those of the subsequent R–R interval. Defined that sleep onset had occurred after 30 s from the start time of the first data subset having negative correlation coefficient and then we estimated that time as SOL.

12. Methods (8/8) 12 Statistical Analysis Shapiro–Wilk test Differences between the SOLs reported by PSG and those estimated using our method was examined by the paired samples t-test.

13. Results (1/4) 13 R-J and R-R intervals before and after sleep onset

14. Results (2/4) 14

15. Results (3/4) 15

16. Results (4/4) 16 Comparison of the SOLs determined by PSG and estimated using our method

17. Conclusion (1/2) 17 Comparison of the mean absolute error (MAE) between SOLs recorded by PSG and estimated by each method

18. Conclusion (2/2) 18 The limitations of our study include the relatively small sample size. It is necessary to conduct more experimental validations on subjects in the wide range of age groups.

19. Personal Remark 19 Correlation coefficients

20. Thanks for your attention 20