Kawasaki, Japan
Kawasaki, Japan

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Shirouzu S.,Japanese Research Institute of Healthcare and Education | Seno Y.,Nazareth Kindergarten | Tobioka K.,Institute of Man and Science Inc. | Yagi T.,Ota Memorial Sleep Center | And 3 more authors.
3rd IEEE EMBS International Conference on Biomedical and Health Informatics, BHI 2016 | Year: 2016

We tried to improve the sleep assessment method from the accelerations (ACC) and RR interval variations (RRIV) thar were measured with newly developed small and light-weight wearable ECG and ACC measuring devices (M-BIT). We performed the simultaneous measurement of M-BIT and polygraph, and verified the validity of our ACC-based sleep/awake identification method, and studied the relationships among parameters obtained through the time frequency analysis of M-BIT ECG RRIV, para-sympathetic (PSNS) and sympathetic nervous system's activity (SNS), coefficients of variation of RR intervals (CVRR), RRIV based respiration frequency (RFRE), its variation width in an epoch (VRFRE), heart rate (HR), and polygraph sleep stages. © 2016 IEEE.


Hashizaki M.,Omron Corporation | Nakajima H.,Omron Corporation | Tsutsumi M.,Omron Healthcare Co. | Shiga T.,Omron Healthcare Co. | And 8 more authors.
Sleep and Biological Rhythms | Year: 2014

Due to the busy lifestyles of people in developed countries, insufficient sleep has emerged as a central health issue in the general population. Objective home sleep monitoring is preferable for identifying sleep problems and improving sleep quality. Several instruments, most notably wrist actigraphy, have been used for this purpose. However, various impediments, including economic and practical concerns, have continued to hamper the widespread use of self-sleep monitoring. In this study, we used the contactless biomotion sensor based on SleepMinderTM with a frequency band modified from 5.8 GHz to 10.525Hz to comply with Japanese Radio Law. The purpose of the study was to validate the accuracy of the sleep-wake algorithm for adult outpatients used by this new sensing system. We examined the data using simultaneous polysomnography and compared the results with previous contactless biomotion sensor and actigraphy studies. Data were collected at two institutions, the Ota Memorial Sleep Center and Kuwamizu Hospital. In total, 211 adult subjects participated in the study, and 148 (99 subjects with apnea-hypopnea index score>15) were used for the analysis. The overall accuracy of the new system was 84.1%, and its sensitivity and specificity were 91.8% and 37.6%, respectively. The automated algorithm slightly overestimated total sleep time (bias: +13min) and sleep efficiency (bias: +3%) compared with polysomnography. As for sleep onset latency and wake time after sleep onset, these were slightly underestimated. The results are comparable to previous contactless biomotion sensor and actigraphy studies, and indicate that this modified contactless biomotion sensor is sufficiently accurate for monitoring sleep-wake patterns in this population. © 2014 Japanese Society of Sleep Research.


Okada S.,Ritsumeikan University | Ohno Y.,Osaka University | Shimizu S.,Osaka University | Kato-Nishimura K.,Ota Memorial Sleep Center | And 3 more authors.
Biomedical Engineering Letters | Year: 2011

Purpose: Obtaining an adequate amount of sleep is a necessity for normal childhood development. Gross body movements (GMs) during sleep in normal children vary by sleep stage and developmental state, and abnormalities in GMs characterize specific developmental pathophysiologies. Therefore, GM monitoring in children is of great importance when tracking normal development. While videosomnography is a widely used technique for monitoring GMs, it is qualitative, and a quantitative method for assessing GMs is required. We developed a novel, simple noncontact method based on video analysis for the detection of GMs during sleep. Methods: Our method used image difference processing of videos to detect GMs. We conducted a preliminary evaluation of our technique by assessing the relationships between sleep stages determined by polysomnography and GMs assessed by the video images of 14 young children (3-7 years old). Results: Our experiments suggest that this method may be used to detect GMs during sleep in children. The rates of GMs during sleep in children significantly differed among wake, light sleep, and slow wave sleep stages. However, rapid eye movement sleep was difficult to distinguish, probably due to age-related changes in neurological development. Conclusions: Our novel method could detect GMs during sleep by difference processing of video images, and we demonstrated the possible utility of this technique for assessing sleep in children. Our proposed technique requires further evaluation, but we suggest that GM detection via video images may be more useful than the presently available qualitative methods. © 2011 Korean Society of Medical and Biological Engineering and Springer.


Kimura A.,Jikei University School of Medicine | Chiba S.,Jikei University School of Medicine | Capasso R.,Stanford University | Yagi T.,Ota Memorial Sleep Center | And 3 more authors.
Laryngoscope | Year: 2013

Background and Objectives The phenomena of periodic cycles of vascular engorgement on the nasal cavity mucosa that alternate between right and left sides are termed the "nasal cycle." The physiologic mechanisms underlying this cycle have not been entirely clarified, even more so during sleep. In this study, we measured the periodic patterns of the normal nasal cycle, not only during wakefulness but also during sleep. Study Design: Case Series Methods Our team utilized a method for functional rhinologic assessment, the portable rhinoflowmeter (Rhinocycle, Rhinometrics, Lynge, Denmark), measuring airflow independently through each nostril during 24 hours on 20 healthy subjects aged 20 to 56 years, and without any nasal pathology or diagnosed medical, psychiatric, or sleep disorders. In addition, a nocturnal polysomnogram was simultaneously performed during sleep. Results Nineteen of 20 subjects showed a detectable nasal cycle, and 16 of 19 subjects presented a change of the cyclic phase during sleep. The mean nasal cycle duration was 234.2±282.4 minutes (median, 164.1 minutes), although variation was considerable. The mean cycle duration time during sleep was significantly longer than that in wakefulness (P <0.005). The reversal of cyclic phase during sleep tended to be associated with REM sleep (68.8%) and postural changes (18.8%). It never occurred in slow-wave sleep. Conclusions Nasal cycle duration during sleep is longer than in wakefulness. Changes in laterality of nasal cycle frequently coincide with switches in posture, tend to occur in REM sleep, never occur in slow-wave sleep, and may be absent in subjects with severe nasal septal deviations. Level of Evidence 4. Laryngoscope, 123:2050-2055, 2013 © 2012 The American Laryngological, Rhinological and Otological Society, Inc.


Tachibana M.,Osaka University | Kato T.,Osaka University | Kato-Nishimura K.,Osaka University | Kato-Nishimura K.,Ota Memorial Sleep Center | And 3 more authors.
Oral Diseases | Year: 2016

Objectives: The aims of this study were to investigate the prevalence of sleep bruxism in children in Japan, and its relationships with sleep-related factors and daytime problematic behavior. Subjects and Methods: Guardians of 6023 children aged 2–12 years completed the Japanese Sleep Questionnaire. Multiple regression analysis and structural equation modeling were performed. Results: Sleep bruxism was reported in 21.0% children (n = 1263): the prevalence was highest in the age group of 5–7 years (27.4%). Multiple regression analysis showed that sleep bruxism had significant correlations with age 5–7 years (OR: 1.72; P < 0.0001), ‘Moves a lot during sleep’ (OR: 1.47; P < 0.0001), ‘sleeps with mouth open’ (OR: 1.56; P < 0.0001), and ‘snores loudly’ (OR: 1.80; P < 0.0001). In structural equation modeling, sleep bruxism had a significant but weak direct effect on daytime problematic behavior, while sleep bruxism significantly correlated with obstructive sleep apnea, which had a higher direct effect on daytime problematic behavior. Conclusions: Sleep bruxism was reported in 21.0% of Japanese children and had independent relationships with age, movements during sleep, and snoring. A comorbidity of sleep-disordered breathing might be related to daytime problematic behavior in children with sleep bruxism. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd

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