Welcome to Okada Labo!

Welcome to  Okada Labo ! 
  We devoted biological and physiological engineering. We have four main themes, Development of biomedical sensors, Stress control, Healthcare monitoring, and Development of Sports instrumentation. Additionally,Dr. Shima Okada is an expert on sleep research.

Sleep Monitoring for...

  • Focus on the ambulatory, unconsciousness, noninvasive and long-term monitoring in daily life.
  • Apply our technologies for clinical and commercial producs.

 Many of our research area include sleep, but not be limited to only sleep research. Our research key words are Medical,  Welfare, Healthcare, Sports and so on.

Please join our Labo tour. We are always waiting for you!

Message from Dr.Okada

 Hello, I am Shima Okada (Ph.D).My research area is Biomedical Engineering. Especially, I
deal with sleep research. Our Labo Member is keen for research and very friendly! Please feel free to join our Labo tour! We are always waiting for your coming (*^_^*)!


共同研究をお考えの企業または大学関係者の方はFor collaborative researchをご覧ください.

Main Research Topics

 Videosomnography is a common way to monitor sleep conditions in non-contact and non-restrictive. In this way, the observer visually examines and notes the body movements from a recorded video. The patient’s sleep is evaluated for an entire night by this method. However, videosomnography analysis requires a lot of time because one data set extends up to 10 hours. Therefore, we propose the automatic videosomnography method using difference video image processing.

An approach for sleep assessment using Body Movement


In recent years, it is known that children’s behavioral disorders are related to sleep disorders. Thus it is important to assess the children's sleep. It is said that there is a tight relationship between sleep stage and body movements. This study focused on the relationship to assess the sleep quality . Hence, We  investigated the body movement measurement technique using video analysis. We can measure the body movements in noninvasive and non contact way by using this technique. We applied this technique for assessment of Obstructive Sleep Apnea Syndrome (OSAS) therapeutic efficacy. We calculated the amount of body movement by video analysis. And we compared the sum of body movement before OSAS treatment and after. As the result, the sum of body movement decreased significantly after OSAS treatment in patients whom OSAS was completely cured. However, the sum of body movement did not decrease after OSAS treatment in patients whom OSAS was not cured. This findings show the possibility that children’s sleep could be assessed by this technique.

The amount of movement in each sleep stage for the four subjects is shown in Figure 1. The body movement after treatment in subject A showed a remarkable decrease at every sleep stage compared with body movement before treatment. The body movement after treatment in subject B also showed a reduction in stages 2 and 3 comparing with body movement before treatment; however, there was little decline in stage 4. The body movement after

treatment in subject C showed a small reduction at the REM stage; however, the body movement after treatment showed an increase in all the other stages. As for the result of subject D, the body movement did not show any obvious trend before or after medical treatment. The results of subject A and B showed a clear reduction in the amount of body movement in all sleep stage. However, the results of subject C showed a significant increase in body movement after the treatment, especially in stages 2, 3 and 4. He had a severe form of the disease. His AHI indices were 50.8 and 28.3 before and after medical treatment, respectively. This subject was, therefore, not considered to have been sufficiently cured after medical treatment. For subject D, there was no significant reduction in the body movement. This can be explained by the factor: A mild form of the disease (the AHI was only 2.2 before medical treatment).


Figure1. The amount of body movement in each sleep stage for all subject

We investigated the body movement measurement technique using video analysis to assess the children’s sleep. And we applied this technique for assessment of OSAS therapeutic efficacy. As the result, we confirmed that it could be possible to assess the therapeutic efficacy of OSAS by using body movement measurement technique. However, more cases need to be assessed in order to provide a more definite conclusion. 



  • 工学の生体機能解明への応用
  • 工学の医療・福祉応用
  • 生体機能の工学応用




サブページ (2): Member Research Achievement