• Journal of The Korean Society of Integrative Medicine
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• v.10 no.3
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• pp.185-198
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• 2022

Purpose : We conducted a study to propose comparing subjective sleeping states data that was collected through scientifically measuring by using smartwatch and surveys for seafarers. In addition, we conducted a study to provide sleep though analysis of the environmental factors that influence the sleep efficiency of seafarers. Methods : For scientific measurement of seafarers' sleeping states, we measured the sleep hours and sleep efficiency for at least 3 days by using the healthcare function of smartwatches which are wearable devices. As for subjective sleeping states, we collected data on sleep hours and satisfaction rates on the quality of sleep through a survey. Lastly, as for the environmental factors that affect the sleep efficiency which is measured by smartwatches such as physical environment, bedroom space, bedroom furniture, bedding, a survey by self-evaluation method was conducted. Results : There were significant differences in the scientific sleep hours measurement values for all seafarers and the average sleep hours in the subjective survey. There were significant differences in the scientific sleep efficiency measurements of all the seafarers and the sleep satisfaction of the subjective survey, and there was no correlation between the scientific sleep efficiency and the subjective sleep satisfaction of all the seafarers. Among the environmental factors affecting the sleep efficiency of the seafarers, humidity variable had the most influence, and vibration and illuminance variables were also shown to have a very significant effect. Conclusion : We propose the measuring method that can analyze the quantitative and qualitative sleep states of the seafarers by using small activity recorders. In addition, it is very important to control humidity, vibration, and illuminance among ship environmental factors, and comfort, noise and bedroom size should also be reflected.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.3
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• pp.433-444
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• 2020

This study proposes a method to improve the sleep stage and efficiency estimation of sleep apnea patients using a UWB (Ultra-Wideband) radar. Motion and respiration extracted from the radar signal were used. Respiratory signal disturbances by motion artifacts and irregular respiration patterns of sleep apnea patients are compensated for in the preprocessing stage. Preprocessing calculates the standard deviation of the respiration signal for a shift window of 15 seconds to estimate thresholds for compensation and applies it to the breathing signal. The method for estimating the sleep stage is based on the difference in amplitude of two kinds of smoothed respirations signals. In smoothing, the window size is set to 10 seconds and 34 seconds, respectively. The estimated feature was processed by the k-nearest neighbor classifier and the feature filtering model to discriminate between the sleep periods of the rapid eye movement (REM) and non-rapid eye movement (NREM). The feature filtering model reflects the characteristics of the REM sleep that occur continuously and the characteristics that mainly occur in the latter part of this stage. The sleep efficiency is estimated by using the sleep onset time and motion events. Sleep onset time uses estimated features from the gradient changes of the breathing signal. A motion event was applied based on the estimated energy change in the UWB signal. Sleep efficiency and sleep stage accuracy were assessed with polysomnography. The average sleep efficiency and sleep stage accuracy were estimated respectively to be about 96.3% and 88.8% in 18 sleep apnea subjects.

• Journal of the Ergonomics Society of Korea
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• v.24 no.2
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• pp.79-83
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• 2005

In order to verify the effects of sleep efficiency and sleep latency depending on the sound, Polysomnography was carried for the different sound stimulations, such as Sound A(providing R bed Co.), Sound B(1/f fluctuation sound develope by KRISS), and no sound stimulation. In case of sleep efficiency and WASO(wake after sleep onset) ratio Sound B shows more affirmative effect than no sound stimulation or Sound B. It is the result that the effect is caused because 1/f fluctuation sound has the rule and unexpectation. This research results show the possibility of application and development of the sound for sleep.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.4
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• pp.307-312
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• 2007

This study was performed to evaluate sleep efficiencies and conditions for comfortable sleep based on the analysis of sleep efficiency and MST under four thermals conditions ($22^{\circ}C,\;24^{\circ}C,\;26^{\circ}C,\;30^{\circ}C$). Five female subjects who have similar life cycle and sleep patterns were participated for the sleep experiment. Their age was from 20 to 22 years old. They were healthy, and had regular sleep with consistent bed and wakeup time. It was checked whether they had a good sleep before the night of experiment. Experiments were performed in an environmental chamber using thermo-hygrostat. The physiological signal (EEG) for sleep stage were obtained from C3-A2 and C4-Al electrode sites. Sleep stages were classified, then SWS latency and SWS/TST were calculated for the evaluation for sleep efficiencies on thermal conditions. As results, mean skin temperature for comfort sleeping was $34.5{\sim}35.4^{\circ}C$. Considering sleep efficiency and mean skin temperature, indoor room temperature of upper limit was $28.1^{\circ}C$.

• Clinics in Shoulder and Elbow
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• v.26 no.2
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• pp.169-174
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• 2023

Background: Sleep quality, quantity, and efficiency have all been demonstrated to be adversely affected by rotator cuff pathology. Previous measures of assessing the impact of rotator cuff pathology on sleep have been largely subjective in nature. This study was undertaken to objectively analyze this relationship through the use of activity monitors. Methods: Patients with full-thickness rotator cuff tears at a single institution were prospectively enrolled between 2018 and 2020. Waist-worn accelerometers were provided for the patients to use each night for 14 days. Sleep efficiency was calculated using the ratio of the time spent sleeping to the total amount of time that was spent in bed. Retraction of the rotator cuff tear was classified using the Patte staging system. Results: This study included 36 patients: 18 with Patte stage 1 disease, 14 with Patte stage 2 disease, and 4 patients with Patte stage 3 disease. During the study, 25 participants wore the monitor on multiple nights, and ultimately their data was used for the analysis. No difference in the median sleep efficiency was appreciated amongst these groups (P>0.1), with each cohort of patients demonstrating a generally high sleep efficiency. Conclusions: The severity of retraction of the rotator cuff tear did not appear to correlate with changes in sleep efficiency for patients (P>0.1). These findings can better inform providers on how to counsel their patients who present with complaints of poor sleep in the setting of full-thickness rotator cuff tears.

• Safety and Health at Work
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• v.10 no.3
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• pp.254-259
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• 2019

Background: This cross-sectional study assessed the sleep quality using the ActiGraph and investigated the relationship between the parameters of sleep assessment and the type of shift work in Korean firefighters. Methods: The participants were 359 firefighters: 65 day workers (control group) and 294 shift workers (shift work group: 77 firefighters with 3-day shift, 72 firefighters with 6-day shift, 65 firefighters with 9-day shift, and 80 firefighters with 21-day shift). Sleep assessments were performed using the ActiGraph (wGT3X-BT) for 24 hours during day shift (control and shift work group) and night shift and rest day (shift work group). The participants recorded bed time and sleep hours during the measurement period. Results: Sleep efficiency, total sleep time, and percentage of wake after sleep onset during night work were lower in the shift work group than control group (p < 0.05). Sleep efficiency decreased in night shift and increased in rest day, whereas wake after sleep onset increased in night shift and decreased in rest day (p < 0.05). Among shift work groups, sleep efficiency of 6-day shift was higher in day shift, and sleep efficiency of 21-day shift was lower in night shift than other shift groups (p < 0.05). Conclusion: We found that the sleep quality in night shift of the shift work group was poorer than the control group. As to the type of shift work, sleep quality was good in 6-day shift and poor in 21-day shift. Thus, fast rotating shift such as 6-day shift may be recommended to improve the sleep quality of the firefighters.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2002.05a
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• pp.181-185
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• 2002

The purpose of this study was to find out the relationship between sleep physiological signals data and subjective feeling of sleep quality. Sixteen subjective were investigated and they slept on both comfortable mattress and uncomfortable mattress. Information of sleep stage is one of the most important clues for sleep quality. Polysomnography is basically the recording of sleep. The several channels of brain waves (EEG), eyes (EOG), chin movements (EMG) and heart (ECG) were monitored. Sixteen subjects spent 6 days and nights in the laboratory and the data of sleeping 7h for each of 3 nights was analyzed. Percentage of deep sleep (III and IV, sleep efficiency, WASO, stage 1 and subjective feeling of sleep quality were significantly affected with mattress types (comfortable and uncomfortable mattress). When subjects slept on comfortable beds, percentage of deep sleep and sleep efficiency were higher than those of uncomfortable bed. The percentages of wake after sleep onset and stage 1 were lower when subject slept in a comfortable bed. The subjective feeling of sleep quality agreed with the recorded sleep data also.

• Sleep Medicine and Psychophysiology
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• v.3 no.1
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• pp.79-84
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• 1996

Kleine-Levin syndrome is a disorder characterized by recurrent episodes of hypersomnia, hyperphagia and hypersexuality that typically occur weeks or months apart. A 17-years-old male showed these episodes and took nocturnal polysomnography(NPSG) and multiple sleep latency test(MSLT). As results of NPSG, sleep latency was 82.5min, sleep efficiency was 82.5min, sleep efficiency was 82.5%, latency and percentage of REM sleep were 106.5min and 14.6% and percentage of slow wave sleep was 12.7%. In 4 times MLST, average of sleep latency and REM latency were 8min 7sec and 5min 20sec with 3 times sleep onset REM period(SOREMP). These findings are consistent with these of Keine-Levin syndrome. And the possible causes and classification of this syndrome were discussed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.1
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• pp.214-217
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• 2017

In this paper, we propose a sleep efficiency measurement algorithm based on IR-UWB radar sensor in distance. Among the vital signs which can be measured by the IR-UWB radar sensor such as breathing rate, heartbeat rate, and movement, we analyzed correlation between the movement and the sleep efficiency, and based on the result, we propose a sleep efficiency measurement algorithm. In order to verify the performance of the proposed algorithm, we applied the algorithm to three polysomnography patients in hospitals and obtained the performance of an average absolute error within 3.9%.

• Journal of Sasang Constitutional Medicine
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• v.33 no.1
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• pp.102-108
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• 2021

Objectives The purpose of this study was to identify differences in sleep by Sasang constitutional type using Pittsburgh Sleep Quality Index(PSQI). Methods The subjects of this study were 3,578 people who had information on Sasang constitutional type and PSQI among the data established at the Korean Medicine Data Center. We compared each item score in PSQI (subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbance, use of sleep medication, daytime dysfunction) and PSQI global scores by Sasang constitutional type using analysis of variance. Logistic regression was conducted to calculate the odds ratio of poor sleep by Sasang constitutional type. Results & Conclusions The SE type showed statistically significantly higher scores than the TE type and SY type in subjective sleep quality, sleep latency, habitual sleep efficiency, sleep disturbance, and PSQI global score, indicating poor sleep compared to other constitutional types. The odds ratio for poor sleep also shows that even after adjusting sex, age, height, and weight, the SE type was significantly higher than other constitutional types, indicating that the SE type could be a risk factor for poor sleep.