The purpose of this study was to examine mattress comfort in terms of subjective handling of the material, sinkage, firmness, elasticity (resilience), warmth, turning over, and width (size), and proposed a causal model of overall sleeping comfort. A web-based survey was conducted with 360 participants (180 males and 180 females) aged 50 to 89 to investigate factors related to sleeping comfort. The results indicated that individuals with a lower BMI rated mattress width (size) more favorably, suggesting that physical characteristics may influence mattress selection. To examine the causal model of sleeping comfort, multiple regression analysis was performed with comfort as the dependent variable and subjective handling of the material, sinkage, firmness, elasticity (resilience), warmth, turning over, and width (size) as independent variables. Simultaneous multi-population analysis was conducted to further analyze the causal model of overall comfort. In the four-factor model related to overall comfort, sinkage, turning over, width (size), and warmth were significantly related. A comparison between the analysis results for the 20-49 and 50-89 age groups showed that sinkage, warmth, and width (size) were common influential factors. The primary difference was that elasticity (resilience) had a smaller effect for the 50-89 age group, while the influence of turning over increased. For turning over, the effect was particularly strong among older males, potentially due to physical changes (e.g., pain). Furthermore, by categorizing participants into mature (50-64 years), early elderly (65-74 years), late elderly (75-89 years), and by gender, changes in the influence of factors were observed. Meanwhile, in the six-factor model, sinkage, firmness, elasticity (resilience), warmth, turning over, and width (size) were significantly related. The findings suggest the need to consider physical information such as height, weight, body type, and physical condition, including factors like pain.

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The purpose of this study was to examine the relationships between singing lullabies at bedtime and sleep problems in infant/toddler. A web-based survey was conducted on 300 adults (164 male, 134 female, mean age 36.18 years, SD = 6.34 years) responsible for children aged 1–35 months old. The results showed that in 27.67% of all families, caregivers sing lullabies to their children at bedtime. Results of multivariate logistic regression analysis showed that singing lullabies at bedtime (AOR = 1.84, 95% CI: 1.03 - 3.38), attending a daycare or certified nursery school (AOR = 1.94, 95% CI: 1.17 - 3.26), NOT sleeping in a separate room from the caregiver (AOR = 0.34, 95% CI: 0.12 - 0.85) were significantly associated with sleep problems in children as assessed by caregivers. This finding suggests that singing lullabies at bedtime might not be beneficial for children’s sleep. However, as this is a cross-sectional study, the causal relationship remains unknown. Further examination of confounding variables, including through longitudinal studies and an analysis of the content and presentation of lullabies, is needed in the future.

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Daytime physical activity (PA) and nocturnal sleep influence each other, with daytime PA patterns potentially playing a key role in determining sleep quality. This study examined the association between daytime PA patterns, including their regularity and fragmentation, and sleep cycle stability, as a potential marker of sleep quality in healthy young male adults. Sleep cycle stability was defined as the stability of the rapid eye movement-non-rapid eye movement (REM-NREM) sleep cycle. Sixteen participants wore accelerometers for 6–8 days to measure daytime PA patterns and underwent polysomnography to assess sleep. The regularity (PAr) and fragmentation (PAf) of daytime PA patterns were calculated from accelerometer data, while sleep cycle stability (SCs) and other sleep parameters were derived from hypnograms. Pearson correlation analysis revealed a positive correlation between PAr and SCs, and a negative correlation between PAf and SCs. Furthermore, SCs showed a positive correlation with mean sleep efficiency, and negative correlations with the mean values of sleep latency and REM sleep latency (REM latency), as well as the standard deviations of these parameters. These findings suggest that more regular and less fragmented daytime PA patterns are associated with more stable sleep cycles, which in turn is linked to shorter sleep and REM latency, higher sleep efficiency, and greater day-to-day stability in these parameters. Interventions targeting daytime PA patterns may provide a potential new avenue for improving sleep quality.

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Sleepiness during activities impairs brain function and is a cause of reduced motivation, mood, and performance. It is also a major factor in causing human errors. Sleepiness can be categorized into subjective sleepiness, which is the feeling of being sleepy, and physiological sleepiness, which is the actual act of falling asleep. The factors that cause sleepiness during activities include the accumulation of sleep debt resulting from insufficient sleep, poor sleep quality, or sleep disorders. Sleep environment is one of the causes of sleep-loss and poor sleep quality. This article provides an overview of the effects of sleep deprivation on brain function, methods for evaluating subjective and physiological sleepiness, and human errors caused by sleepiness, including traffic accidents

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It is widely recognized that sleep duration among the Japanese population is relatively short, a phenomenon that is believed to be influenced by a range of cultural and social factors. Among these, long working hours are frequently cited as a potential contributing factor. However, the relationship between working hours and sleep duration has not been empirically examined in a systematic manner. In fact, it is inherently difficult to empirically establish a direct causal relationship between a social factor such as working hours and an individual behavioral outcome such as sleep duration. Given that sleep is influenced by numerous interrelated variables, it is virtually impossible to isolate and empirically examine the effect of working hours alone. What can be attempted is an inference based on data that appear to be relevant to this issue. The present study, therefore, aims to present empirical data that may help inform this issue. In recent years, a number of studies have investigated international comparisons and temporal changes in both sleep and working hours. Drawing upon these datasets, this paper seeks to explore the potential relationship between working hours and sleep duration in the context of Japan.

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Sleep is one of the most important physiological function in supporting mental and physical health. Recently published "Sleep guideline 2023" is an important tool in enhancing sleep health among the community. Many people is suffering for sleep problems including insomnia, but most of them do not seek for medical assistance. Recent advances in hypnotic medication may help these patients in receiving proper and safer treatment. In improving sleep health among the community and the patients suffering for sleep problems, not only the effort by the health care providers but also the involvement of industry is essential. Recent trends in sleep hygiene improvement and hypnotic medication is explained, putting emphasis on the importance of multi-disciplinary approach among the medical professionals and industry-academia collaboration.

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