Neighborhood-level socioeconomic factors moderate the association between physical activity and relative age effect: a cross-sectional survey study with Japanese adolescents.

BACKGROUND: Relative age effect is defined as a phenomenon where children born early generally perform better than children born later in the same cohort. Physical activity is an important factor that might be influenced by the relative age effect. Socioeconomic factors (e.g., parent's income, education level) are also associated with the adolescent's physical activity. However, no existing study has examined whether socioeconomic factors moderate the relative age effect on the adolescent's physical activity. This study aims to clarify whether and how birth month and socioeconomic factors relate to organized sports and physical activity among adolescents in Japan. METHODS: We conducted a questionnaire survey targeting 21,491 adolescents who live in a widespread neighborhood. We included 8102 adolescents (4087 males and 4015 females: mean age 13.1 ± 1.4) in the analysis. Based on the participants' birth months, we divided them into four groups (April to June, July to September, October to December, January to March). We asked participants to report their organized sports participation. Using the International Physical Activity Questionnaire for Japanese Early Adolescents, we identified their moderate to vigorous physical activity (MVPA). Neighborhood-level socioeconomic factors (areal deprivation, average annual income, education level) were analyzed based on national surveys, such as the population census. We performed multilevel logistic and linear regression analysis for organized sports participation and MVPA, respectively. Moreover, a simple slope analysis was implemented if the interaction between birth month and socioeconomic factor was significant in the multilevel linear regression analysis. RESULTS: Among males, relatively younger adolescents (adolescents who were born later in the same grade) were less likely to participate in organized sports activites (OR=0.90, 95% CI 0.82-0.97, p<0.05), while both males and females engaged in less MVPA (b=-0.54, b=-0.25, p< 0.01, respectively). We observed an interaction between birth month and socioeconomic factors. Among males in low-income neighborhoods, and females in more deprived neighborhoods, relatively younger adolescents engaged in less MVPA. CONCLUSIONS: Socioeconomic factors moderate the relative age effect on adolescents' physical activity. The relative age effect on adolescents' physical activity might be more likely to appear among adolescents from socioeconomically disadvantaged neighborhoods.

Incidence, clinical characteristics and long-term prognosis of postoperative symptomatic venous thromboembolism: a retrospective cohort study.

OBJECTIVES: The purpose of this study was to evaluate the incidence, clinical characteristics and prognosis of postoperative symptomatic venous thromboembolism (VTE) in Japan. DESIGN: Retrospective observational study. Two data sets, Contemporary ManageMent AND outcomes in patients with Venous ThromboEmbolism (COMMAND VTE) Registry and Japanese Society of Anesthesiologists (JSA) annual report, were used for current analyses. SETTING: Eighteen of 29 centres participated in the COMMAND VTE Registry. PARTICIPANTS: Acute symptomatic patients with VTE who had undergone surgery 2 months prior to the diagnosis at 18 centres from January 2010 to December 2013 were identified in the COMMAND VTE Registry. From each centre's JSA annual report, the overall population that had received anaesthetic management during this period was retrieved. INTERVENTIONS: None. PRIMARY AND SECONDARY OUTCOME MEASURES: The primary outcome was the incidences and clinical characteristics of postoperative symptomatic VTE. The secondary outcomes were recurrent VTE, major bleeding and all-cause death. RESULTS: We identified 137 patients with postoperative symptomatic VTE, including 57 patients with pulmonary embolism. The incidences of postoperative symptomatic VTE and pulmonary embolism were 0.067% and 0.028%, respectively, based on data from 2 03 943 patients who underwent surgery, managed by anaesthesiologists, during the study period. The incidences of postoperative symptomatic VTE varied widely, depending on surgical and anaesthetic characteristics. Postoperative symptomatic VTE occurred at a median of 8 days after surgery, with 58 patients (42%) diagnosed within 7 days. The cumulative incidence, 30 days after VTE, of recurrent VTE, major bleeding, and all-cause death was 3.0%, 5.2%, and 3.7%, respectively. CONCLUSION: This study, combining the large real-world VTE and anaesthesiology databases in Japan revealed the incidence, clinical features and prognosis of postoperative symptomatic VTE, providing useful insights for all healthcare providers involved in various surgeries. TRIAL REGISTRATION: Not applicable.

Intraoperative Diagnosis of Bronchovenous Fistula During Lung Transplantation Using Transesophageal Echocardiography.

Bronchovenous fistula (BVF) is a rare complication and can cause arterial gas embolism in vital organs, including the heart and the brain, resulting in a high mortality rate. A 51-year-old man developed a BVF during pneumonectomy for lung transplantation, which quickly was diagnosed by transesophageal echocardiography (TEE). He required highairway-pressure ventilation due to his severely restrictive ventilatory impairment and had severe left pleural adhesion due to a history of pleurodesis. Intraoperatively, he had a coronary air embolism and required temporary treatment with central venoarterial extracorporeal membrane oxygenation (VA-ECMO), but showed no postoperative cardiac or neurologic complications. BVF may be formed during lung transplantation because lung transplantation recipients often receive high-airway-pressure ventilation and are vulnerable to bronchi and pulmonary vessel injuries during surgery. Intraoperative TEE can contribute to the early detection of air bubbles in the left heart circulation and is helpful for the prevention of arterial gas embolism.

Association of Neighborhood Food Environment and Physical Activity Environment With Obesity: A Large-Scale Cross-Sectional Study of Fifth- to Ninth-Grade Children in Japan.

Objective: This study examined the relationship between neighborhood food and physical activity environment, and obesity among elementary and junior high school students in Japan. Methods: The participants were fifth- to ninth-grade children (n=7277), who were attending municipal schools in Japan. Percent overweight (POW) was calculated using their age, gender, height, and weight, which were collected through a questionnaire. A POW of < 20% was considered non-obese, while ≥ 20% was considered obese. Furthermore, using a geographic information system, we investigated the density of convenience stores, fast-food stores, casual restaurants, supermarkets and department stores, parks, sports facilities, stations, and intersections in the school district. Additionally, from the census, we obtained information regarding the population density of the municipality where the participants' schools were located. Multiple logistic regression analysis was used to examine the relationship between obesity and food environment (the food environment model), between obesity and physical activity environment (the physical activity environment model), and among obesity, food, and physical activity environment (the food and physical activity environment model). Results: In the food environment model and the food and physical activity environment model, the density of convenience stores showed a significant positive association. In the physical activity environment model, the density of stations showed a significant negative association. Conclusion: This study's findings can contribute to the development of appropriate community interventions for improving children's health in Japan and similar areas.

Effects of whole blood storage in a polyolefin blood bag on platelets for acute normovolemic hemodilution.

Acute normovolemic hemodilution (ANH) is a potential transfusion method for platelets, as well as for red blood cells. However, previous studies have shown that whole blood storage in ANH decreases platelet aggregability by 14.7-76.3% and that this decrease is not recovered by reinfusion. We investigated whether a new whole blood storage method for 6 h using a polyolefin bag, based on the platelet concentrates storage method, would maintain platelet function better than the conventional method using a polyvinyl chloride bag. We demonstrated that storage of whole blood in a polyolefin bag maintained ADP-induced aggregation rates at more than twofold higher than those in a polyvinyl chloride bag, and also significantly suppressed P-selectin expression, a platelet activation marker (ADP-induced aggregation rates: 24.6 ± 5.1% vs. 51.7 ± 11.5%, p = 0.002; P-selectin expression; 50.3 ± 8.4MFI vs. 31.6 ± 9.3MFI, p = 0.018). These results could be attributed to the high gas permeability of polyolefin, which lowered PCO2 and maintained a high pH with or without agitation. There were no significant changes in platelet count and red blood cell parameters due to the storage methods. Our results suggest that ANH using polyolefin bags is advantageous in improving hemostatic function compared to the conventional method.

Activation of the ß-adrenergic receptor exacerbates lipopolysaccharide-induced wasting of skeletal muscle cells by increasing interleukin-6 production.

The skeletal muscle mass has been shown to be affected by catecholamines, such as epinephrine (Epi), norepinephrine (NE), and isoproterenol (ISO). On the other hand, lipopolysaccharide (LPS), one of the causative substances of sepsis, induces muscle wasting via toll-like receptors expressed in skeletal muscle. Although catecholamines are frequently administered to critically ill patients, it is still incompletely understood how these drugs affect skeletal muscle during critical illness, including sepsis. Herein, we examined the direct effects of catecholamines on LPS-induced skeletal muscle wasting using the C2C12 myoblast cell line. Muscle wasting induced by catecholamines and/or LPS was analyzed by the use of the differentiated C2C12 myotubes, and its underlying mechanism was explored by immunoblotting analysis, quantitative reverse transcription polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA), and the TransAM kit for p-65 NF-κB. Epi augmented myosin heavy chain (MHC) protein loss and reduction of the myotube diameter induced by LPS. LPS induced C/EBPδ protein, Atrogin-1 and inteleukin-6 (IL-6), and these responses were potentiated by Epi. An IL-6 inhibitor, LMT28, suppressed the potentiating effect of Epi on the LPS-induced responses. NF-κB activity was induced by LPS, but was not affected by Epi and recombinant IL-6, and the NF-κB inhibitor, Bay 11-7082, abolished Atrogin-1 mRNA expression induced by LPS with or without Epi. NE and ISO also potentiated LPS-induced IL-6 and Atroign-1 mRNA expression. Carvedilol, a nonselective ß-adrenergic receptor antagonist, suppressed the facilitating effects of Epi on the Atrogin-1 mRNA induction by LPS, and abolished the effects of Epi on the MHC protein loss in the presence of LPS. It was concluded that Epi activates the ß-adrenergic receptors in C2C12 myotubes and the IL-6-STAT3 pathway, leading to the augmentation of LPS-induced activation of the NF-κB- C/EBPδ-Atrogin-1 pathway and to the exacerbation of myotube wasting.

A case of left ventricular free wall rupture after insertion of an IMPELLA® left ventricular assist device diagnosed by transesophageal echocardiography.

BACKGROUND: The IMPELLA® is a minimally invasive left ventricular assist device. We report a case in which transesophageal echocardiography (TEE) was useful in diagnosis of left ventricular rupture after IMPELLA® insertion. CASE PRESENTATION: A 75-year-old man presented to the emergency room with chest pain and underwent percutaneous coronary intervention for 100% stenosis of the left anterior descending branch #7. An IMPELLA® was inserted to stabilize the circulation, but hypotension persisted. Transthoracic echocardiography revealed increased pericardial effusion and suspicion of free wall left ventricular rupture, leading to emergency surgery. TEE revealed the IMPELLA® straying into the left ventricle apical wall and cardiac tamponade. Hemorrhage was observed from the thinning free wall and the tip of the IMPELLA® was palpable. The IMPELLA® was removed and the left ventricular wall was repaired. CONCLUSIONS: The IMPELLA® requires implantation of the tip in the left ventricle, but it should be noted that a fragile ventricular wall can be easily perforated.

Relationship between maternal healthy eating literacy and healthy meal provision in families in Japan.

This study examined the effects of maternal healthy eating literacy (HEL) on healthy meal provision in Japanese families. We conducted an online cross-sectional survey with 1899 mothers of pre-school children. Participants were divided into two groups based on their median score of eating out and consuming convenience foods, and demographic variables were compared between these groups. We assessed associations between HEL and healthy meal provision using Pearson's correlation coefficient (r) and multiple linear regression with healthy meal provision as the dependent variable and HEL as the independent variable, adjusting for age, education, work styles, household income, number of children and whether participants lived with a partner. Mothers exhibiting high scores on eating out/consuming convenience foods were more likely to be employed (p = 0.004), have only one child (p = 0.034), have lower education (p=0.011) and exhibit lower healthy meal provision (p < 0.001) and HEL scores (p < 0.001). In addition, HEL was associated with healthy meal provision (ß = 0.34, p < 0.001). Among mothers with higher scores on eating out/consuming convenience foods, HEL was associated with healthy meal provision (ß = 0.32, p < 0.001). This study suggests that maternal HEL is associated with healthy meal provision regardless of the degree of eating out/consuming convenience food. Thus, interventions to improve maternal HEL can help mothers to provide healthy meals when they eat out or consume convenience foods as family meals.

Reliability and validity of a short Japanese version of the UPPS-P Impulsive Behavior Scale.

OBJECTIVE: This study aimed to verify the reliability and validity of a Japanese version of the S-UPPS-P Impulsive Behavior Scale. This is expected to facilitate comparisons of findings between international and Japanese samples in studies of impulsivity. METHODS: Two surveys were conducted. In the first survey, 632 participants, aged 20-44 years old, completed a translated version of the Japanese S-UPPS-P Impulsive Behavior Scale, the Motor Impulsiveness Scale, a short form of the Big-Five scale, the short Grit scale, and the brief version of the self-control scale. Two weeks later, the second survey containing the S-UPPS-P and the motor impulsiveness scale were completed by 450 participants who had completed the first survey to examine test-retest reliability. RESULTS: In the first survey, an exploratory factor analysis was performed on the S-UPPS-P responses. A four-factor solution was the most suitable solution, with the factors of "Lack of Perseverance," "Lack of Premeditation," "Sensation Seeking," and "Negative-Positive Urgency." Then, a confirmatory factor analysis was performed. The conformity index of the original five-factor model was slightly better than that of the four-factor model. We also compared the five-factor model's conformity index with three other models that had been examined in the original and other foreign language versions of the S-UPPS-P. The five-interrelated factor model had the best model fit. The reliability of the five scales was confirmed. The scales exhibited internal consistency with α coefficients ranging from 0.65 to 0.79, in addition to the test-retest reliability ranging from 0.74 to 0.80. The convergent validity of each S-UPPS-P scale was supported by high relationships with the four personality scales, with the highest correlation coefficients ranging from 0.37 to -0.67. CONCLUSION: The reliability and validity of the Japanese version of the S-UPPS-P were confirmed, despite the minor limitations of the exploratory factor analysis providing a four-factor solution instead of a five-factor solution, and the α reliability coefficients of two scales being acceptable but rather low. Thus, comparisons of findings between international and Japanese studies on impulsivity could be facilitated.

The relationship between sleep habits, lifestyle factors, and achieving guideline-recommended physical activity levels in ten-to-fourteen-year-old Japanese children: A cross-sectional study.

The current focus of meeting the physical activity guidelines for children and young people include preventing conditions such as high blood cholesterol, high blood pressure, metabolic syndrome, obesity, low bone density, depression, and injuries. However, the relationship between sleep habits and meeting physical activity guidelines is still unclear. This study aimed to assess this relationship among fifth- to eighth-grade (ages 10-14) Japanese children. This cross-sectional study included 3,123 children (boys: 1,558, girls: 1,565, mean age: 12.5 ± 1.2 years). Questionnaires were used to assess parameters such as moderate-to-vigorous physical activity per day, school and weekend night sleep durations, social jetlag, daytime sleepiness, napping, screen time, and breakfast intake. Participants were divided into an achievement and a non-achievement group depending on their physical activity guideline achievement status (i.e., whether they met the children's physical activity guideline of 60 min or more of moderate-to-vigorous physical activity per day). Then, to determine the sleep habits in relation to the children's achievement of guideline-recommended physical activity levels, multivariate logistic regression analyses were conducted. In fifth- and sixth-grade (ages 10-12) boys, an inverse association was observed between physical activity guideline achievement and daytime sleepiness. In seventh- and eighth-grade (ages 12-14) boys, physical activity guideline achievement was inversely associated with social jetlag and skipping breakfast. Additionally, in seventh- and eighth-grade girls, physical activity guideline achievement was inversely associated with inappropriate sleep duration on weekends and screen time. These results suggest that meeting the physical activity guideline is related to favorable sleep habits in Japanese children. However, their relevance may differ by school type and gender.

Rocuronium Has a Suppressive Effect on Platelet Function via the P2Y12 Receptor Pathway In Vitro That Is Not Reversed by Sugammadex.

Rocuronium is an aminosteroid nondepolarizing neuromuscular blocker that is widely used for anesthesia and intensive care. In this study, we investigated the effect of rocuronium on human platelet functions in vitro. The effects of rocuronium on platelet aggregation, P-selectin expression, and cyclic adenosine monophosphate (cAMP) levels in platelets were measured using an aggregometer, an enzyme immunoassay, and flow cytometry, respectively. Rocuronium inhibited ADP-induced platelet aggregation, P-selectin expression and suppression of cAMP production. These effects were not antagonized by equimolar sugammadex, a synthetic γ-cyclodextrin derivative that antagonizes rocuronium-induced muscle relaxation by encapsulating the rocuronium molecule. Morpholine, which constitutes a part of the rocuronium molecule but is not encapsulated by sugammadex, inhibited ADP-induced platelet aggregation. Vecuronium, which has a molecular structure similar to that of rocuronium but does not possess a morpholine ring, had no significant effect on ADP-induced platelet aggregation. These results indicate that rocuronium has a suppressive effect on platelet functions in vitro that is not reversed by sugammadex and suggest that this effect is mediated by blockade of the P2Y12 receptor signaling pathway via the morpholine ring of rocuronium.

Does upper-body elevation affect sleepiness and memories of hypnagogic images after short daytime naps?

The present study aimed to examine the effects of a somatosensory stimulus on sleepiness and memories of hypnagogic imagery during short daytime naps. Participants experienced two daytime nap conditions: (1) a somatosensory stimulus was created by raising the upper part of the bed 20 min after turning off the light and (2) a somatosensory stimulus was not created; the angle of the upper part of the bed remained flat. Approximately 20 min and 30 s after turning off the light, participants were awakened and questioned regarding their subjective sleepiness and the presence or absence of hypnagogic imagery. Results showed that subjective sleepiness following the nap was reduced only in the raised condition, and hypnagogic imagery in the raised condition was lower than that in the flat condition. These findings may provide insight on developing new techniques for improving subjective conditions after awakening.

Use of argatroban in combination with nafamostat mesilate in open-heart surgery for a pediatric patient with heparin-induced thrombocytopenia type II: a case report.

BACKGROUND: Heparin-induced thrombocytopenia type II (HIT II) is a rare, immune-mediated complication of heparin therapy and can cause life-threatening thromboembolism. However, perioperative anticoagulation therapy for patients with a complication of HIT II has not been established. CASE PRESENTATION: A 6-year-old boy with tetralogy of Fallot underwent radical intracardiac repair with administration of argatroban at 1 year old due to positive HIT antibody. Reoperation was scheduled for pulmonary valve insufficiency, using argatroban and nafamostat mesilate as anticoagulants. Argatroban has a long onset time and the activated coagulation time (ACT) requires 7-26 h to return to the preadministration level, making hemorrhage control difficult, while half-life of nafamostat mesilate is shorter than that of argatroban. Celite ACT reflects the effects of both argatroban and nafamostat mesilate, but kaolin ACT reflects only the effect of argatroban. Due to the early termination of argatroban administration based on Celite and kaolin ACTs, ACT recovered to ≤ 200 s at 5 h after the end of argatroban administration. CONCLUSION: Celite and kaolin ACTs can be used as markers to obtain close control of the required dose of argatroban in combination with nafamostat mesilate for the management of HIT II patients.

Presentation of familiar odor induces negative dream emotions during rapid eye movement (REM) sleep in healthy adolescents.

OBJECTIVE: Odor presentation is a crucial tool in the experimental investigation of dreaming since odors rarely cause arousal, and are processed in the brain during sleep. Our previous study demonstrated that the presentation of a preferred odor during rapid eye movement (REM) sleep-induced negative dream emotions. However, preference and familiarity of an odor are known to be strongly related to each other in olfactory perception. Consequently, the above result might have been due to the confounding effects of familiarity. Therefore, the present study was designed to clarify the effects of an individual's degree of familiarity with an odor on negative emotions experienced when dreaming. METHODS: The airflow with phenylethyl alcohol (PEA: rose-like smell) was presented as a stimulus of experimental condition, and odorless airflow was presented as the control. Participants who were familiar (n = 7) and unfamiliar (n = 7) with the odor of PEA experienced both conditions during REM sleep in the second and later sleep cycle. Then, they were awakened, and they rated the characteristics of their dream using a questionnaire. RESULTS AND CONCLUSIONS: Participants who were familiar with the odor of PEA rated their dreams more negatively in the experimental condition relative to the control condition. It is concluded based on these results that a familiar odor may induce negative emotion in dreams, possibly because familiar odors tend to be perceived more strongly, and the olfactory pathway has direct connections to the amygdala, which is primarily involved in processing negative emotions.

Preschool children's eating and sleeping habits: late rising and brunch on weekends is related to several physical and mental symptoms.

OBJECTIVE: As the relationships of sleep-wake schedule and mealtime with children's behaviors have not often been studied together, we investigated the relationships of these lifestyles variables with preschool children's well-being. METHODS: Using a network survey, we investigated several lifestyle variables of 1000 families with preschool children. RESULTS: Our previous articles reported that preschool children's bedtime was delayed by the compulsory nap routine in Japanese nursery schools. The present study revealed similar results. We conducted a cluster analysis with children's meal and sleep time data, which yielded five different lifestyle groups. Cluster 1 was characterized by "extremely late and irregular" meal and sleep times; similar to Cluster 1, Cluster 2 was a "late and irregular" lifestyle group. Cluster 3 was a "mildly late" lifestyle group. Cluster 4 was an "early bird and regular lifestyle" group, and Cluster 5 resembled the "early bird and regular lifestyle" group on weekdays, but was "late and irregular on weekends." It was found that the later and more irregular the children's meal and sleep times, the worse their physical and mental condition. Even for Cluster 5, the children who had early and regular meal and sleep times on weekdays, getting up and having breakfast late and irregularly on weekends showed worse physical and mental conditions. These problematic symptoms observed in children with late meal and sleep times on weekends might be partly associated with the irregularity of their habits and partly associated with delayed mealtime, especially for breakfast (brunch). CONCLUSION: A stable lifestyle, including a regular sleep and wake schedule and mealtime, is important for preschool children's mental and physical health.

[Kanashibari Phenomenon as a Sleep Disorder: Recurrent Idiopathic Sleep Paralysis].

The phenomenon called kanashibari in Japan is otherwise known as sleep paralysis and, is an established symptom of narcolepsy. Its physiological correlate is an unusual occurrence of rapid eye movement (REM) sleep, i.e., sleep onset REM periods (SOREMPs). Various symptoms of the phenomenon are explained by the mechanisms of REM sleep. SOREMPs can be observed in various situations, which indicate a lower amplitude of circadian rhythms, such as during interupted sleep, acute reversal of sleep and wakefulness cycle, and disrupted sleep of depressive patients and in newborn babies. The lifetime prevalence of the phenomenon in the general population is as high about 40%. The phenomenon can be a mysterious and frightening experience far affected people and called as various names according to the folklore beliefs of local communities, e.g., nightmare in Europe, hexendrücken in Germany, cauchemar in France, and old hag in Newfoundland. Japanese college students are known for their very short sleep length and disturbed sleep wake rhythms. Many students claim to have experienced daytime sleepiness. Some of them meet the criterion concerning sleep latencies and frequency of SOREMPs for multiple sleep latency test (MSLT) as narcolepsy. SOREMPs are frequently seen in healthy college students with certain lifestyles. Practitioners should be cautious to diagnose narcolepsy if the student shows disturbed sleep wake schedules.

A ß1-tubulin-based megakaryocyte maturation reporter system identifies novel drugs that promote platelet production.

During maturation, megakaryocytes (MKs) express ß1-tubulin (TUBB1) and rearrange their microtubule components to enlarge, form proplatelets, and eventually release platelets. The development of a platform to identify in vitro conditions that would efficiently promote MK development could potentially enable large-scale platelet production. Here, we show that an immortalized MK cell line (imMKCL) genetically modified to express the ß1-tubulin-Venus reporter provides a practical system to efficiently monitor the in vitro production of platelet-like particles (PLPs). The Venus transgene was inserted downstream of the TUBB1 locus in imMKCLs using CRISPR/Cas9, and the expression was visualized by Venus fluorescence intensity. This imMKCL reporter line was then used for high-throughput drug screening. We identified several compounds that significantly improved the efficiency of PLP production in vitro under feeder-free conditions and showed a significant tendency to recover platelets in vivo in a mouse thrombocytopenia model induced by anti-GPIbα antibody administration. Interestingly, most of these compounds, including a WNT signaling pathway inhibitor, Wnt-C59, antagonized the aryl hydrocarbon receptor (AhR) to increase PLP production, confirming the crucial role of AhR inhibition in MK maturation. Consistently, small interfering RNA treatment against AhR increased the Venus intensity and PLP production. TCS 359, an FLT3 inhibitor, significantly increased PLP production independently of FLT3 or AhR. This study highlights the usefulness of the ß1-tubulin reporter MK line as a useful tool to study the mechanisms underlying thrombopoiesis and to identify novel inducers of ex vivo platelet production.

Favorite odor induces negative dream emotion during rapid eye movement sleep.

OBJECTIVE: As connections between nightmares and various psychiatric disorders have been reported, the clinical significance of studying dream emotionality is now growing in importance. Because the olfactory bulb connects directly to the amygdala odor presentation may be a crucial tool to study dream emotions. Previous studies have demonstrated that presentation of positive/negative odors during rapid eye movement (REM) sleep affects various aspects of dreaming. Although olfactory perception can be influenced by personal experiences, the role of individual preferences in the effects of olfactory stimuli on dreaming has not yet been clarified. The purpose of the current study was to clarify the effects of odor on dreaming during REM sleep, taking individual preferences into account. METHODS: Phenyl ethyl alcohol (rose-like smell) airflow was presented as an experimental stimulus, and odorless airflow was presented as the control. Participants who like (n = 7) and dislike (n = 8) the odor of phenyl ethyl alcohol were presented air with and without the odor of phenyl ethyl alcohol, respectively, during REM sleep and then awakened to report and rate their dream contents. Thereafter, the transcribed dream reports were rated by independent raters. RESULTS AND CONCLUSIONS: Participants who liked the odor of phenyl ethyl alcohol reported more emotionally negative dreams when they were presented with phenyl ethyl alcohol airflow than that with odorless airflow. In other words, the participant's favorite odor was associated with emotionally negative dreams. These findings could be attributed to the nature of odor perception and the characteristics of brain activities during REM sleep.