Multiparameter Sleep Monitoring Using a Depth Camera - Biomedical Engineering Systems and Technologies - page 296

detection was 89.3% (SD = 0.014) in the side-lying position and it was 89.3% (SD =
0.0003) in the supine position. Besides, in the circumstance of sleeping with a thin
quilt, the measurement accuracy of head detection was 99.9% (SD = 0.007) in the
side-lying position and it was 98.8% (SD = 0.17) in the supine position. Moreover,
the measurement accuracy of torso detection is 99.4% (SD = 0.0003) in the side-lying
position and it is 99.9% (SD = 0.003) in the supine position. The experimental results
of head and torso detection are shown in Fig. 9. Overall, the average accurate rate of
head detection was 96.7% (SD = 0.073), and the average accurate rate of torso detec-
tion was 96.8% (SD = 0.031).

Fig. 8. A Realistic Overnight-Sleep Monitoring. Red color indicates the ground truth measured
by RIP and actigraphy, and the blue color indicates the results of our system. (a) The results of
breathing rate and sleep positions. (b) The movement level detected by an actigraphy. (c) The
movement level detected by our system.

Head Detection Torso Detection

100%

80%

99.9%

99.9%

98.8%

60%

89.4%

89.3%

89.3% 99.4%

40%

99.9%

20%

0%

Side lying Supine Side lying Supine

Sleep without quilt Sleep with a thin quilt

Fig. 9. Measurement results of head and torso detection in experiment II

For body movement, the times of the movement events in our method and actigra-
phy were compared. According to the observation, we observed that big body move-
ment can be measured both in our system and actigraphy, such as the event of turning