The value of circadian heart rate variability for the estimation of obstructive sleep apnea severity in adult males.

OBJECTIVES: Heart rate variability (HRV) is becoming more prevalent as a measurable parameter in wearable sleep-monitoring devices, which are simple and effective instruments for illness evaluation. Currently, most studies on investigating OSA severity and HRV have measured heart rates during wakefulness or sleep. Therefore, the objective of this study was to investigate the circadian rhythm of HRV in male patients with OSA and its value for the estimation of OSA severity using group-based trajectory modeling. METHODS: Patients with complaints of snoring were enrolled from the Sleep Center of Shandong Qianfoshan Hospital. Patients were divided into 3 groups according to apnea hypopnea index (AHI in events/h), as follows: (<15, 15≤AHI<30, and ≥30). HRV parameters were calculated using 24 h Holter monitoring, which included time-domain and frequency-domain indices. Circadian differences in the standard deviation of normal to normal (SDNN) were evaluated for OSA severity using analysis of variance, trajectory analysis, and multinomial logistic regression. RESULTS: A total of 228 patients were enrolled, 47 with mild OSA, 48 moderate, and 133 severe. Patients with severe OSA exhibited reduced triangular index and higher very low frequency than those in the other groups. Circadian HRV showed that nocturnal SDNN was considerably higher than daytime SDNN in patients with severe OSA. The difference among the OSA groups was significant at 23, 24, 2, and 3 o'clock sharp between the severe and moderate OSA groups (all P<0.05). The heterogeneity of circadian HRV trajectories in OSA was strongly associated with OSA severity, including sleep structure and hypoxia-related parameters. Among the low-to-low, low-to-high, high-to-low, and high-to-high groups, OSA severity in the low-to-high group was the most severe, especially compared with the low-to-low and high-to-low SDNN groups, respectively. CONCLUSIONS: Circadian HRV in patients with OSA emerged as low daytime and high nocturnal in SDNN, particularly in men with severe OSA. The heterogeneity of circadian HRV revealed that trajectories with low daytime and significantly high nighttime were more strongly associated with severe OSA. Thus, circadian HRV trajectories may be useful to identify the severity of OSA.

Beneficial effects of oral supplementation with ferulic acid, a plant phenolic compound, on the human skin barrier in healthy men.

Ferulic acid (FA) is a phytochemical compound with various physiologic functions. To clarify the effect of FA intake on skin barrier function (SBF), we conducted a placebo-controlled double-blind pilot trial. Sixteen healthy subjects were divided into 2 groups (n = 8) and ingested capsules containing either FA (200 mg) or placebo daily for 2 weeks. Two measures of SBF, transepidermal water loss and stratum corneum hydration, were assessed before and 2 weeks after the start of the study. Autonomic nervous activity, which is suggested to be related to SBF, was also measured. Compared with the values obtained before the start of the study, FA intake significantly reduced transepidermal water loss (from 6.1 ± 1.1 to 4.8 ± 1.0 g/m2/h, p = 0.005) and increased stratum corneum hydration (from 30.1 ± 7.6 to 32.3 ± 8.1 a.u., p = 0.027) after 2 weeks. In addition, the amount change in sympathetic nervous activity was significantly reduced after ingesting the FA capsules compared with the placebo capsules (-0.7 ± 1.6 vs. 1.1 ± 1.4, p = 0.035). These findings suggest that FA supplementation decreases sympathetic nervous activity and strengthens SBF in healthy men.

Analysis of effects of acute hypovolemia on arterial stiffness in rabbits monitored with cardio-ankle vascular index.

Although elasticity of the conduit arteries is known to be contribute effective peripheral circulation via Windkessel effects, the relationship between changes in intra-aortic blood volume and conduit artery elasticity remains unknown. Here we assessed the effects of change in intra-aortic blood volume induced by blood removal and subsequent blood transfusion on arterial stiffness and the involvement of autonomic nervous activity using our established rabbit model in the presence or absence of the ganglion blocker hexamethonium (100 mg/kg). Blood removal at a rate of 1 mL/min gradually decreased the blood pressure and blood flow of the common carotid artery but increased a stiffness indicator the cardio-ankle vascular index, which was equally observed in the presence of hexamethonium. These results suggest that arterial stiffness acutely responds to changes in intra-aortic blood volume independent of autonomic nervous system modification.

Listening to J.S. Bach's "Brandenburg Concerto No. 4 in G Major" May Suppress the Sympathetic Nervous Activity.

This study aimed to investigate the effects of listening to Wolfgang Amadeus Mozart's "Sonata for two pianos in D major, K448" and Johann Sebastian Bach's "Brandenburg concerto No. 4 in G major, BWV1049" on the heart rate, blood pressure, and autonomic nervous activity. Seventeen healthy young adults were recruited as participants. All participants underwent a 10-minute rest, a 10-minute load test, and a triplicate 8-minute music listening process. Electrocardiograms were continuously measured from the measurement onset to completion. Moreover, the high-frequency (HF) component was extracted from the heart rate variability analysis as a measure of the parasympathetic nervous activity and the ratio of low frequency (LF) to HF as a measure of the sympathetic nervous activity. Blood pressure was also measured. There was a significant decrease in the heart rate after listening to both K448 and BWV1049, as well as in the silence state. Blood pressure did not significantly change in either case. Further, the LF/HF ratio significantly decreased after listening to BWV1049. Nevertheless, HF did not change after listening to either music. In conclusion, this study suggests that listening to K448 does not affect the heart rate, blood pressure, or autonomic nervous activity, whereas listening to BWV1049 may suppress the sympathetic nervous activity in healthy adults.

Differential effects of remimazolam and propofol on heart rate variability during anesthesia induction.

PURPOSE: The effects of remimazolam on autonomic nervous activity have not been elucidated. We investigated the differential effects of remimazolam and propofol on autonomic nervous activity during anesthesia induction. METHODS: Thirty patients were randomly divided into a remimazolam group or a propofol group for anesthesia induction. Hemodynamics and indices of heart rate variability were recorded before and after anesthesia. Low frequency power (LF; 0.04-0.15 Hz, ms2) and high frequency power (HF; 0.15-0.4 Hz, ms2) were calculated from power spectral density of heart rate variability. LF reflects both sympathetic and parasympathetic activities and HF reflects parasympathetic activity. To investigate the balance between sympathetic and parasympathetic activities, the normalized unit (%) of LF (LF nu) and that of HF (HF nu) were calculated. Changes in LF nu (ΔLF nu) before and after anesthesia (ΔLF nu = LF nu at awake-LF nu after anesthesia) were compared between the groups. RESULTS: Remimazolam and propofol decreased blood pressure and power spectral density of heart rate variability. Remimazolam did not change LF nu and HF nu, while propofol increased LF nu and decreased HF nu (P = 0.020). ΔLF nu in the remimazolam group (1.4 ± 23.6%) were less than that in the propofol group (19.3 ± 22.4%, P = 0.0415). CONCLUSION: Remimazolam and propofol decreased autonomic nervous activity during anesthesia induction. Remimazolam preserved the balance of sympathetic and parasympathetic activities, while propofol modulated it to sympathetic dominance.

Effect of restraint inside the transport vehicle on heart rate and heart rate variability in Thoroughbred horses.

This study aimed to investigate the effect of transportation and restraint in a van on heart rate (HR) and HR variability in Thoroughbreds. Eight healthy Thoroughbreds were exposed to four conditions, each for a duration of 30 min: stall rest (REST), restraint inside a van (VAN), restraint inside a van with the engine running (V + E), and road transportation (TRANS). Electrocardiograms were recorded to determine HR, low-frequency (LF) power, high-frequency (HF) power, and LF/HF ratio. During TRANS, HR was significantly greater than during REST and V + E. There was a significant increase during VAN compared with REST. These results demonstrated that restraint inside the transport vehicle was one of the major stressors that may cause physiological changes during transportation.

Gender-Based Vegetarian and Nonvegetarian Dietary Impact on Cardiac Autonomic Function of Heart Rate Variability.

Objective: Cardiovascular disease is one among the major mortality threats throughout the world. Autonomic activity of the nervous system can be examined by heart rate variability (HRV) analysis. Association of sympathetic and parasympathetic activities is directly related to HRV modulation. The aim of the study is to determine variations in HRV parameters among adult/adolescent male and female subjects due to vegetarian and nonvegetarian diet.Method: Ninety undergraduate students in each male and female group (N = 180) volunteered for the study. Based upon food habits, male and female subjects were categorized into four groups. Short-term (5-minute) heart rate recordings were measured from the subjects in a seated position before breakfast with minimum of 12 hours' fasting. Two-way analysis of variance was performed among the time and frequency domain variables.Results: Time domain variables are observed as significant (p < 0.05) between vegetarian males and females and also (p < 0.05) between male vegetarian and female nonvegetarians for standard deviation of NN intervals. Frequency domain HRV indices such as low frequency (LF; p = 0.01), high frequency (HF; p = 0.0001), and LF/HF (p < 0.001) resulted between male and female vegetarians. Significance of LF (p = 0.02), HF (p < 0.0001), and LF/HF (p < 0.01) was measured between male vegetarians and female nonvegetarians. LF (p = 0.02), HF (p = 0.04), and LF/HF (p = 0.002) resulted between nonvegetarian males and females. HF (p = 0.05) was enumerated between male vegetarians and nonvegetarians.Conclusions: Significant predominance of sympathetic cardiac activity was observed among male nonvegetarian consumers more than female vegetarians. Analysis demonstrates that the gender-based influence of vegetarian and nonvegetarian diet has significant correlation under HRV measurements.

Vascular Endothelial Dysfunction and Autonomic Nervous Hyperactivity among Premenopausal Women with Cold-Sensitivity Constitution (Hiesho).

The cold-sensitivity constitution (CSC), termed "Hiesho" in Japanese, is a woman-specific cold sense of peripheral sites. The etiology of and criteria for CSC are not yet well established. We defined CSC as temperature gradient > 6˚C between body surface and core, and investigated the autonomic nervous activity by measuring heart rate variability and the vascular endothelial function by determining reactive hyperemia index (RHI) in 43 healthy premenopausal women, aged 18-47 years. Twenty five women had CSC during both the follicular and luteal phases of their menstrual cycles (sustained-CSC group), 8 women did not show CSC during both phases (non-CSC group), and the remaining 10 women showed CSC in either menstrual phase (occasional CSC). To identify the pathophysiological bases of CSC, we compared the sympathetic nervous activity and vascular endothelial function between sustained-CSC and non-CSC. We thus found that sympathetic nervous activity was higher among the sustained-CSC group (p = 0.042) during the follicular phase, compared with the non-CSC group, while the RHI was similar in both groups. Furthermore, the sympathetic nervous activity was similar between the sustained-CSC women aged ≥ 40 years (n = 10) and those aged < 40 years (n = 15) during either menstrual phase, whereas the RHI of the women aged < 40 years was lower during the follicular phase (p = 0.045), compared with the women aged ≥ 40 years. In conclusion, CSC is associated with sympathetic nervous hyperactivity in premenopausal women, and vascular endothelial dysfunction is also involved in CSC among younger women.

The predictive value of heart rate variability indices tested in early period after radiofrequency catheter ablation for the recurrence of atrial fibrillation.

INTRODUCTION: To explore the relationship between recurrence of atrial fibrillation (AF) and the autonomic nervous activity evaluated by heart rate variability (HRV) indices after radiofrequency catheter ablation (RFCA) in the early period. METHODS: We enrolled 102 patients with paroxysmal AF and tested the HRV indices by the high-resolution Holter electrocardiogram the next morning after RFCA. The HRV indices were compared between the non-recurrence group (n = 85) and the recurrence group (n = 17). RESULTS: The HRV indices included standard deviation of normal to normal intervals (SDNN), SDNN index, root-mean square successive differences (RMSSD), the proportion of normal to normal intervals differing by >50 millisecond (ms) (pNN50), high-frequency components (HF), low-frequency components (LF) and very low-frequency components were significantly higher in recurrence group than that in non-recurrence group, while no such difference was found for LF/HF. Based on the median value of the recurrent time (9 months), RMSSD (P = .012), pNN50 (P < .0001) and HF (P = .033) were lower in late recurrence group than that in early recurrence group. The Cox regression analyses indicated that higher values of RMSSD (P = .01), pNN50 (P = .02) and HF (P = .02) were associated with a higher risk of recurrence after adjusted for covariates. The receiver operating characteristic curves showed higher rates of clinical recurrence of AF after RFCA in patients with RMSSD ≥27.5 ms, pNN50 ≥4.5%, and HF ≥178.25 ms2 . CONCLUSIONS: Values of RMSSD, pNN50, and HF tested in the early period after RFCA could independently predict the recurrence of AF.

Parasympathetic nervous activity is associated with oxytocin in multiparous, but not primiparous, women during the perinatal period.

Oxytocin (OXT) is thought to have antidepressant/anxiolytic effects in postpartum women. Primiparous women tend toward an attenuated lactation compared with multiparous women. However, so far, little is known about the relationship between OXT and autonomic nervous activity (ANA) in perinatal women and whether it may be different in primiparous and multiparous women. Therefore, the objective of this study was to answer this question by determining both ANA and salivary OXT levels in primiparous and multiparous perinatal women. In 18 primiparous and 18 multiparous women, who underwent a physical and physiological examination, ANA measurement by heart rate variability and saliva sampling were performed during the perinatal period. Saliva OXT concentration was determined by a highly sensitive ELISA. OXT release into saliva was obtained from multiplying saliva OXT concentration by saliva flow rate. In the postpartum period, multiparous women had higher parasympathetic nervous activity (PNA) and lower physical stress index (PSI) compared with primiparous women. Furthermore, multiparous postpartal women had higher OXT compared with primiparous or multiparous prepartal women. In addition, in multiparous perinatal women, OXT correlated positively with PNA, but negatively with PSI. These results suggest that after parturition, multiparous mothers may switch over to the "feed and breed" system more quickly due to increased OXT compared with primiparous mothers. Our findings support antidepressant/anxiolytic and anti-stress effects of OXT. In postpartal women exposed to synthetic OXT, ANA measurement may provide a clue to clarify the effects of exogenous OXT on postpartum psychiatric disorders.

Modulation of Autonomic Nervous Activity in the Termination of Paroxysmal Atrial Fibrillation.

BACKGROUND: Autonomic nervous activity plays a critical role in the genesis of paroxysmal atrial fibrillation (AF, PAF). However, the role of autonomic nervous activity on AF termination has not been elucidated. Heart rate variability (HRV) is widely used to evaluate autonomic nervous activity in humans. The purpose of this study was to assess whether autonomic nervous activity assessed by HRV contributes to AF termination. METHODS: Electrocardiograms (ECGs) and HRV were studied in patients with termination of sustained (>30 s) PAF by 24-hour ambulatory Holter monitoring. The 20-minute interval after termination of AF was divided into four segments of 5 minutes each, and a frequency analysis was applied to each 5-minute segment. RESULTS: In 52 AF episodes, the ultra-low-frequency power, very-low-frequency power, low-frequency power (LF), high-frequency power (HF), and total power significantly decreased with time after episodes of AF termination. The LF/HF (L/H) ratio, normalized LF (LFnu), and normalized HF (HFnu) significantly changed after AF termination. Eighteen (35%) episodes had decreased LFnu and increased HFnu (sympathetic withdrawal and vagal activation), which had slower average AF ventricular responses (92 ± 16 beats/min vs 105 ± 24 beats/min, P < 0.05) than the AF termination episodes (n = 34, 65%) with increased LFnu and decreased HFnu (sympathetic activation and vagal withdrawal). Moreover, older patients (aged >65 years) had a higher incidence (n = 27, 75%) of AF termination with increased LFnu and decreased HFnu than did younger patients (aged ≤65 years, n = 7, 44%, P < 0.05). CONCLUSION: Autonomic changes critically regulate termination of PAF, which is modulated by aging.

Effects and safety of mechanical bathing as a complementary therapy for terminal stage cancer patients from the physiological and psychological perspective: a pilot study.

OBJECTIVE: In palliative care hospitals in Japan, mechanical bathing is conducted to maintain cleanliness. However, the physiological and psychological influence of mechanical bathing on patients has not been sufficiently studied. The objective of this study was to assess, using physiological and psychological indices, the effects of mechanical bathing care for patients in the terminal stage of cancer. METHODS: Mechanical bathing was performed using a Marine Court SB7000 in a supine or semi-seated position. The heart rate variability analysis method was used to measure autonomic nervous system function. The patients' state of anxiety was assessed using the State-Trait Anxiety Inventory (STAI), a psychological index, and patients' verbal responses were also collected after mechanical bathing. RESULTS: Twenty-four patients were enrolled in this study. Their sympathetic and parasympathetic nervous activity did not differ before and after bathing. A significant difference was found between pre- and post-bathing anxiety, as evaluated by STAI (P < 0.0001). In the patient's verbal responses that was collected, the most frequently mentioned descriptors were 'comfortable' and 'relaxed'. Patients were more relaxed after mechanical bathing according to STAI evaluation and their verbal responses. CONCLUSIONS: The findings suggest that the method of bathing used in this study is safe and pain-relieving for terminal stage cancer patients. It is thus possible to provide safe and comfortable care for terminal stage cancer patients using mechanical baths.

Quantification of autonomic nervous activity by heart rate variability and approximate entropy in high ultrafiltration rate during hemodialysis.

BACKGROUND: Few studies have focused on the imbalance of the autonomic nervous system in ultrafiltration rate (UFR) subjects without blood pressure variation during maintenance hemodialysis (HD), although the role of autonomic nervous system activation during HD has been proposed to be an important factor for the maintenance of blood pressure. METHODS: Variations over time in autonomic nervous activity due to differences in UFR were evaluated by measuring heart rate variability (HRV) and approximate entropy (ApEn) in 35 HD patients without blood pressure variations during HD session. The subjects were divided into 3 groups, those with UFR <10 ml/h/kg; ≥10 ml/h/kg but ≤15 ml/h/kg; and >15 ml/h/kg, and Holter ECG was recorded continuously during HD session using frequency analysis of RR intervals. High frequency (HF) and low frequency (LF) spectral components are found to be representative of the parasympathetic nervous system and sympathovagal balance, respectively, with the ratio of LF to HF of HRV providing a measure of sympathetic nervous system. RESULTS: In subjects with UFR >15 ml/h/kg, HF components were significantly lower, and LF/HF and ApEn values were significantly higher, in the latter half of an HD session than before starting HD. CONCLUSION: Removing water from these subjects would promote sustained sympathetic nervous overactivity. These findings indicate that the UFR during HD needs to be set at ≤15 ml/h/kg.

Relationships between transepidermal water loss, cutaneous microcirculatory function and autonomic nervous activity.

OBJECTIVE: Several studies have shown that a deterioration of skin properties, an impaired cutaneous microcirculatory function and an imbalance of autonomic nervous activity are observed in smokers and in patients with diabetes mellitus or Raynaud's phenomenon. These observations suggest that skin properties are associated with cutaneous microcirculatory function and autonomic nervous activity in pathological conditions. However, there is no published evidence to support the concept that these two functions have any relationship with skin properties even in healthy subjects. To investigate the hypothesis that these properties are related, we conducted a survey of healthy adult subjects to investigate the relationships between cutaneous microcirculatory function and autonomic nervous activity and skin properties. METHODS: The hydration of the stratum corneum and transepidermal water loss (TEWL) were investigated as skin properties, and the responsiveness of skin blood flow (SkBF) to local warming was examined as an index of cutaneous microcirculatory function in 19 healthy adult male subjects. Electrocardiograms were monitored for 24 h and heart rate variability was analysed considering low-frequency power (LF: 0.04-0.15 Hz), high-frequency power (HF: 0.15-0.40 Hz) and a ratio of low- to high-frequency power (LF/HF) as indices of autonomic nervous activity; HF is an index of parasympathetic activity, whereas LF/HF is an index of sympathovagal balance. The relationships between those indices were then analysed. RESULTS: A moderate negative correlation was found between TEWL and the relative maximum rate of increases in the responsiveness of SkBF on local warming. A moderate positive and a moderate negative correlation were observed between TEWL and LF/HF or HF, respectively. Moreover, a moderate negative and a moderate positive correlation were shown between the responsiveness of SkBF and LF/HF or HF, respectively. The hydration of the stratum corneum showed no correlations with any indices of microcirculation or autonomic nervous activity. CONCLUSION: These results indicate that skin barrier function, cutaneous microcirculatory function and autonomic nervous activity are mutually associated in healthy adults.

Changes in heart rate and heart rate variability as a function of age in Thoroughbred horses.

We investigated changes in heart rate (HR) and HR variability as a function of age in newborn foals to old Thoroughbred horses. Experiments were performed on a total of 83 healthy and clinically normal Thoroughbred horses. Resting HR decreased with age from birth. The relationship between age and HR fit the equation Y=48.2X-0.129(R2=0.705); the relationship between age and HR for horses 0-7 years old fit the equation Y=44.1X-0.179(R2=0.882). Seven-day-old horses had the highest HR values (106 ± 10.3 beat/min). The low frequency (LF) and high frequency (HF) powers increased with age in newborn to old horses. These changes in HR and HR variability appear to result from the effects of ageing. Three- to seven-year-old race horses had the lowest HR values (32.9 ± 3.5 beat/min) and the highest LF and HF powers except for the HF powers in the oldest horses. Race training may have contributed to these changes. Horses of ages greater than 25 years old had the highest HF powers and the lowest LF/HF ratios. In individual horses, 8 of the 15 horses over 25 years old had LF/HF ratios of less than 1.0; their HR variability appears to be unique, and they may have a different autonomic balance than horses of younger age.

Relation between circadian blood pressure rhythm and serum albumin level in non-diabetic patients with proteinuria.

It remains unclear whether the abnormal circadian blood pressure (BP) rhythm in non-diabetic chronic kidney disease (CKD) is related to hypoalbuminemia. We evaluated relationships between circadian BP rhythm and serum albumin concentration (SAC) and also examined autonomic nervous activities. Non-diabetic CKD patients with proteinuria (n = 197; 105 men, 92 women; aged 47.0 ± 13.3 years; estimated glomerular filtration rate ≥30 ml/min) were divided into nephrotic syndrome (NS: n = 46, SAC ≤ 30 g/l), hypoalbuminemia (n = 65, 30 < SAC < 40 g/l) and normoalbuminemia (n = 86, SAC ≥ 40 g/l) groups. Non-proteinuria subjects (n = 97, urinary protein/creatinine ratio < 30 mg/g creatinine) were enrolled as the non-proteinuria group. Ambulatory 24 h BP monitoring was conducted in all subjects. Simultaneously, power spectral analysis of heart rate was performed to evaluate the sympathovagal balance. Waking BP was lower in the hypoalbuminemia and NS groups than the other groups. Sleeping/waking mean BP ratio was not different between non-proteinuria (0.87 ± 0.07) and normoalbuminemia (0.89 ± 0.08) groups, but increased significantly (p < 0.05) in the hypoalbuminemia (0.92 ± 0.08) and NS groups (0.96 ± 0.08). Significant reverse correlations were observed between SAC and sleeping/waking mean BP ratio (r = -0.274, p < 0.001) in all patients. Multivariate regression analysis identified SAC and sympathovagal balance as predictors of increased sleeping/waking BP ratios as the dependent variable. In non-diabetic CKD patients with proteinuria, disturbed circadian BP rhythms were related to SAC and 24 h sympathovagal imbalance.

The effect of fast eating on the thermic effect of food in young Japanese women.

The relationship between eating speed and the thermic effect of food (TEF) remains unclear. We investigated the difference in the TEF when meals containing the same amount of energy were eaten in 5 min (fast eating) or 15 min (regular eating). Subjects were nine non-obese young women. Following a 350 kcal (1464 kJ) meal, energy expenditure and autonomic nervous system activity were measured. The frequency of mastication was also calculated. The TEF for the 15-min period after the start of eating with fast eating was significantly lower than with regular eating (p < 0.01). There was a significant positive correlation between the low-frequency/high-frequency ratio and TEF at 5-min intervals up to 20 min after the start of eating and between total mastication frequency and TEF during ingestion. Fast eating may reduce the TEF, potentially because a decrease in mastication frequency decreases sympathetic nervous system activity.

Neuroregulatory Effects of Microcone Patch Stimulation on the Auricular Branch of the Vagus Nerve and the Prefrontal Cortex: A Feasibility Study.

Background: The primary purpose of this study was to preliminarily examine the effects of autonomic nervous system activity on the dorsolateral prefrontal cortex. Recent studies have examined approaches to modulating autonomic activity using invasive and non-invasive methods, but the effects of changes in autonomic activity during cognitive tasks on the dorsolateral prefrontal cortex have not been fully investigated. The purpose of this preliminary investigation was to examine changes in autonomic activity and blood oxygen saturation in the dorsolateral prefrontal cortex during reading tasks induced by vagus nerve stimulation using a microcone patch. Methods: A cohort of 40 typically developing adults was enrolled in this study. We carefully examined changes in autonomic nervous system activity and blood oxygen saturation in the dorsolateral prefrontal cortex during a reading task in two conditions: with and without microcone patch stimulation. Results: Significant changes in brain activation in the dorsolateral prefrontal cortext due to microcone patch stimulation were confirmed. In addition, hierarchical multiple regression analysis revealed specific changes in reading task-related blood oxygen saturation in the dorsolateral prefrontal region during microcone patch stimulation. Conclusions: It should be recognized that this study is a preliminary investigation and does not have immediate clinical applications. However, our results suggest that changes in autonomic nervous system activity induced by external vagal stimulation may affect activity in specific reading-related regions of the dorsolateral prefrontal cortex. Further research and evaluation are needed to fully understand the implications and potential applications of these findings.

Assessment of Well-Being Across Menstrual Phases in Female Students.

Purpose: In this study, we determined female nursing students' physical and mental state involvement by measuring heart rate variability and salivary α-amylase activity (αAMY). Methods: The study included 108 students aged 20-21 with regular menstrual cycles. The basal body temperature method was used to determine the menstrual phases. Five indices were used: low and high frequency components, and their ratio, total power, and physical stress index. In addition, αAMY was measured using a salivary amylase monitor. A six-point scale was used for subjective mood evaluation. Repeated measures analysis of variance was performed for differences between groups, and the Tukey-Kramer method was used for multiple comparisons. A p-value of <0.05 was considered statistically significant. Results: The results suggested that the physical fatigue of the luteal phase is carried over into the menstrual phase, and the symptoms concomitant with the menstrual phase may manifest as poor mood. Furthermore, parasympathetic activity and stress coping skills tended to be higher, and sympathetic activity was lower during the menstrual phase, suggesting that students are more relaxed during the menstrual period. Conclusion: Though the results were statistically not significant, the students were in a considerably better mood during the follicular phase than the menstrual phase, suggesting that the physical and mental states may differ between the early and late follicular phases. It may be possible to evaluate the mental and physical condition of female students by obtaining more values.

Peripheral blood flow estimated by laser doppler flowmetry provides additional information about sleep state beyond that provided by pulse rate variability.

Pulse rate variability (PRV), derived from Laser Doppler flowmetry (LDF) or photoplethysmography, has recently become widely used for sleep state assessment, although it cannot identify all the sleep stages. Peripheral blood flow (BF), also estimated by LDF, may be modulated by sleep stages; however, few studies have explored its potential for assessing sleep state. Thus, we aimed to investigate whether peripheral BF could provide information about sleep stages, and thus improve sleep state assessment. We performed electrocardiography and simultaneously recorded BF signals by LDF from the right-index finger and ear concha of 45 healthy participants (13 women; mean age, 22.5 ± 3.4 years) during one night of polysomnographic recording. Time- and frequency-domain parameters of peripheral BF, and time-domain, frequency-domain, and non-linear indices of PRV and heart rate variability (HRV) were calculated. Finger-BF parameters in the time and frequency domains provided information about different sleep stages, some of which (such as the difference between N1 and rapid eye movement sleep) were not revealed by finger-PRV. In addition, finger-PRV patterns and HRV patterns were similar for most parameters. Further, both finger- and ear-BF results showed 0.2-0.3 Hz oscillations that varied with sleep stages, with a significant increase in N3, suggesting a modulation of respiration within this frequency band. These results showed that peripheral BF could provide information for different sleep stages, some of which was complementary to the information provided by PRV. Furthermore, the combination of peripheral BF and PRV may be more advantageous than HRV alone in assessing sleep states and related autonomic nervous activity.