In recent years, music has been attracting attention as a factor that improves the sleep environment. Most studies thus far have examined the effects of music on nighttime sleep or the effects of music therapy; however, the effects of music on napping have not yet been sufficiently examined. This study aimed to investigate the impact of listening to music with a known relaxing effect before napping on the subsequent nap, based on various indices (ex. physiological and biochemical indices). The study was designed as a within-participant experiment, with 13 participants (21.2 ± 0.6 years old) each in the control (silent) and music-listening conditions. In the music-listening condition, music was played over loudspeakers at 50 dB, followed by a 20-minute nap beginning at 14:00. Although the music used in the previous study was found to significantly decrease respiration and heart rate, no significant changes in subjective mood, autonomic nervous system activity, sleep variables, salivary cortisol levels, or performance on cognitive tasks after napping due to music listening were observed in the present study. Furthermore, the results of this study showed that, opposite to expectations, subjective sleepiness was significantly stronger after napping than before napping in the music-listening condition. However, it was suggested that this was not an effect of the music itself but instead the setting of the nap time. This study only examined the effect of a single piece of music on napping, and further validation is needed, considering the type of music presented, the participants' preferences, and the length and timing of the nap.

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The purpose of this study was to investigate that relationships between each factor of impression evaluation of a bedding environment and objective sleep states and subjective sleep feelings. 20 young male adults without problems of sleep took part in our sleep experiment which was conducted for multiple nights in a controlled environment, and the recordings of 15 participants, five nights per participant, were analyzed. We made the impression evaluation form consisting of 25 adjective pairs and conducted factor analysis. In addition, we performed correlation analysis using the factor scores and objective & subjective sleep states. Through the factor analysis, three factors “affinity”, “physical properties” and “visibility” were extracted. The correlation analysis showed that the “affinity” score and subjective sleep feelings after waking showed significant correlation. Moreover, there were significant correlations between the “physical properties” score and objective sleep states associated with Stage 3. On the other hand, there was no correlation for the “visibility” score. The present study is supposed to provide new insights into bedding impression evaluation with the different method from previous studies.

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This study aimed to examine the relationship between caffeine-containing nutritional drink consumption and rest through sleep for employees working in long-term care facilities based on their work type. A self-administered survey was administered to long-term care facility employees, and responses were obtained from 607 participants. The dependent variable was “I get enough rest from sleep,” and the independent variables were face sheet, work type (day-shift only/shift work), hours of sleep, lifestyle (consumption of nutritional drinks containing caffeine, etc.), stress check recommended by the Ministry of Health, Labor, and Welfare, and support from the surrounding community. The independent variables were used for logistic regression analysis, which revealed the relationship between the day-shift-only group and being well-rested in terms of sleep, less consumption of caffeine-containing nutritional drinks, longer average hours of sleep, physical and mental stress in the stress check, and less frequent drinking of alcohol. High caffeine-containing nutritional drink consumption and long average hours of sleep were associated with the shift work group. However, further research should clarify causal relationships because of the cross-sectional study design.

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The COVID-19 (coronavirus disease 2019) pandemic has profoundly changed our lives, affecting sleep and mental/physical health. This review outlines the relationship between COVID-19 and sleep, (1) the impact of COVID-19 and social restriction to prevent the outbreak of COVID-19 on sleep and (2) the impact of sleep on COVID-19 and vaccine effectiveness. Even if COVID-19 is successfully controlled by the development of vaccines and medications, new infectious diseases will appear one after another. In addition to infectious diseases, natural disasters such as earthquakes and floods may force people to live in shelters. We need to learn from this experience, strengthen our preparedness for pandemics, and consider how to maintain good sleep health during emergencies, as well as promote the knowledge about sleep health throughout society.

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