Development of a Japanese version of the Epworth Sleepiness Scale (JESS) based on item response theory

Relationship between sleep variables and interoceptive awareness in daytime workers

Interoception refers to the sensation of internal and physiological bodily states, such as heart rate, and contributes to the maintenance of bodily internal homeostasis. Some studies showed that interoceptive awareness is related to experiencing nightmares and subjective sleep quality. Similarly to the perception of heart rate variability, sleepiness is thought to be mainly evoked by homeostatic processes and is based on the awareness and recognition of internal body signals. However, the relationship between subjective excessive daytime sleepiness and interoceptive awareness has not been addressed. Therefore, this study examined the relationship between interoceptive awareness and multiple sleep variables including subjective excessive sleepiness in daytime workers. A web questionnaire survey was conducted targeting daytime workers in Japan, and data from 461 participants were used for analyses. Multiple regression analyses showed weak but significant relationships between subjective excessive daytime sleepiness, insomnia symptoms, nightmare distress, and dream frequency and the components of interoception awareness measured by the Multidimensional Assessment of Interoceptive Awareness. However, no components of interoceptive awareness were related to workday sleep loss or social jetlag of day workers. The results of this study suggest that subjective sleepiness, in addition to nightmare distress and sleep quality, is associated with interoceptive awareness. To the best of our knowledge, this study is the first to analyze the relationship between subjective daytime excessive sleepiness and interoceptive awareness. Further investigation of this relationship is expected to lead to a better understanding of sleep disorders and to elucidate individual differences in the accuracy of subjective assessments of sleepiness.

Associations Between Cognitive Impairment, Depressive Symptoms, and Work Productivity Loss in Patients With Bipolar Disorder: A Cross-Sectional Analysis

AIM

To evaluate the relationship between cognitive impairment and work productivity loss in patients with bipolar disorder.

METHODS

We enrolled outpatients with bipolar disorder aged 18-59 years undergoing treatment and actively employed or on sick leave. Baseline demographic, medical resource use, and employment data were collected. We evaluated work productivity, cognitive impairment, quality of life (QOL), depressive symptoms (defined as a Patient Health Questionnaire-9 [PHQ-9] score of ≥ 10), and sleep disturbance. This interim analysis examined correlations among baseline symptom scores and correlations of each symptom score with work productivity loss and QOL.

RESULTS

Among 211 participants, cognitive impairment was moderately correlated with depressive symptoms (r = 0.595) and insomnia (r = 0.481), and depressive symptoms and insomnia were highly correlated (r = 0.719) (all p < 0.001). Work productivity loss (presenteeism) was moderately correlated with cognitive impairment (r = 0.474), depression (r = 0.577), and insomnia (r = 0.547) (all p < 0.001). Depression had the strongest influence on presenteeism (multiple regression analysis, regression coefficient: 22.98; p < 0.001). Among participants without severe depressive symptoms (PHQ-9 ≤ 19), cognitive impairment (13.91, p = 0.007) and insomnia (13.80, p = 0.016) strongly affected presenteeism. Among participants without moderately severe or severe depressive symptoms (PHQ-9 ≤ 14), insomnia affected presenteeism (23.14, p = 0.011). QOL was moderately negatively associated with cognitive impairment (r = -0.653), depression (r = -0.699), and insomnia (r = -0.559) (all p < 0.001). In multiple regression analysis, cognitive impairment (-0.12, p < 0.001), depression (-0.12, p = 0.010), and insomnia (-0.16, p < 0.001) were significantly associated with QOL.

CONCLUSIONS

Treatment should focus on improving the core symptoms of bipolar disorder, insomnia, and cognitive impairment.

TRIAL REGISTRATION

UMIN Clinical Trials Registry (UMIN000051519).

Validation of Bangla version of the epworth sleepiness scale: a tool for assessing daytime sleepiness

PURPOSE

This study aimed to evaluate the reliability and validity of the ESS Bangla version (ESS-B) for Bangla speaking population of Bangladesh.

METHODS

This cross-sectional study was conducted over a period of 12 months. A total of 148 Bangla-speaking individuals aged 12-65 years were participated in this study. The original ESS was translated into a Bangla ESS version through several stages including translation, backtranslation, expert review and pretesting. All participants were tested with this questionnaire and retested after two weeks of test. Psychometric properties of ESS-B including internal consistency, test-retest reliability, and validity, were assessed along with exploratory factor analysis.

RESULTS

The ESS-B demonstrated satisfactory internal consistency with a Cronbach's alpha of 0.73. The test-retest reliability of all items including the overall total scores were also satisfactory (τb ranged from 0.496 to 0.662). Convergent validity was supported by a moderately positive correlation with 'daytime dysfunction' of PSQI-B tool (τb = 0.309, p < 0.05), while divergent validity was indicated by a weak positive correlation with 'trouble to relax' component of GAD 7-B tool (τb = 0.175, p < 0.05). Exploratory factor analysis revealed two distinct factor structures corresponding to sedentary activity and active engagement.

CONCLUSION

The ESS-B exhibited satisfactory reliability and validity among the Bangla-speaking population of Bangladesh.

Characteristics of clinical descriptive variables and polysomnographic findings of catathrenia

STUDY OBJECTIVES

Catathrenia has been classified as a sleep-related breathing disorder variant in the third edition of the International Classification of Sleep Disorders, but its validity remains unverified. We analyzed the clinical descriptive variables and polysomnographic findings of catathrenia and discussed the similarities to and differences from those of obstructive sleep apnea, non-rapid eye movement parasomnias, and sleep bruxism (SB).

METHODS

A retrospective analysis was conducted on 47 patients diagnosed with nocturnal groaning through polysomnography. We examined sex, body mass index, age at symptom onset, weekly symptom frequency, and presence/absence of comorbidities, including obstructive sleep apnea, periodic limb movement disorder, non-rapid eye movement parasomnia, and SB. The groaning event index was calculated according to sleep position and sleep stage.

RESULTS

The distribution of patients with catathrenia did not show sex differences (male/female = 20:27), body mass index was 20.6 ± 3.0 kg/m2, and age of onset was 18.2 ± 7.4 years. The groaning event index was higher in stages N1 and R than in stage N3 and in the supine position than in the lateral position. There were no cases complicated with non-rapid eye movement parasomnia, but the complication of SB was observed in 30% of the participants, and SB events appeared immediately before or during the interictal period of the groaning event episodes in these cases.

CONCLUSIONS

Given the clinical background, posture- and sleep stage-dependent appearance of groaning events, and the relatively high complication rate of SB, catathrenia pathogenesis may be heterogeneous or comprise elements of different sleep disorders.

CITATION

Takei Y, Nakayama H, Inoue Y. Characteristics of clinical descriptive variables and polysomnographic findings of catathrenia. J Clin Sleep Med. 2025;21(2):377-381.

Associations Among Sleep Apnea, Objective or Subjective Sleep Duration, and Recurrence of Atrial Fibrillation in Patients Who Undergo Radiofrequency Catheter Ablation for Persistent Atrial Fibrillation - A Prospective Observational Study

BACKGROUND

Sleep apnea (SA), subjective sleep duration (SSD), and objective sleep duration (OSD) were reported as risk factors for atrial fibrillation (AF). However, the association between AF and the combination of SA and OSD has not been clarified. Nor has a mismatch between SSD and OSD been investigated.

METHODS AND RESULTS

We assessed SA with polysomnography, OSD with actigraphy, and SSD in patients who underwent radiofrequency catheter ablation for persistent AF. We investigated associations among SA, OSD, OSD×3% oxygen desaturation index (3%ODI), and AF recurrence, considering SSD-OSD (i.e., the difference between SSD and OSD) and OSD. Seventy of 94 (74.4%) participants had moderate-to-severe SA (apnea-hypopnea index [AHI] ≥15). Participants were classified into OSD tertiles. Participants in Tertile 3 (mean OSD: 7.3 h) had decreased SSD-OSD (0.0 h) with increased Stage N1 sleep. Over 27.6 months, 10 AF recurrences occurred in 51 participants without treatment for SA. AHI ≥20 and OSD Tertile 3 were associated with AF recurrence (hazard ratios 5.7 [95% confidence interval 1.1-24.7] and 10.3 [95% confidence interval 1.2-88.4], respectively). Participants with AF recurrence had a higher OSD×3%ODI.

CONCLUSIONS

SA and long OSD were predictors of recurrent AF through long exposure to intermittent hypoxia during sleep. SSD-OSD was low in patients with long OSD, possibly because of decreased sleep quality.

Clinical impact of restless legs syndrome in patients with migraine: a 12-year, single-center, longitudinal study

Although many studies have indicated a significant association between migraine and restless legs syndrome (RLS), few long-term longitudinal studies have examined RLS in patients with migraine. We conducted a single-center, 12-year, longitudinal study of migraine patients and assessed whether RLS was present in 2010, 2017, or 2022 to evaluate its associations with clinical factors. Headache-related disability was assessed using the Migraine Disability Assessment (MIDAS). Sleep quality, daytime sleepiness, and depressive symptoms were assessed using the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS) and the Beck Depression Inventory-II (BDI-II), respectively. Of the 262 patients included at baseline (2010), 101 were available after 7 years (2017), and 74 were available after 12 years (2022). The RLS incidence rates were 13.7%, 20.8%, and 24.3% in 2010, 2017, and 2022, respectively. The RLS severity score did not significantly differ among the three time points. The persistent RLS group, defined as those who were positive for RLS at the last evaluation in addition to the first and/or second evaluations, had significantly higher MIDAS, BDI-II, PSQI and ESS scores than did the never RLS group, defined as those who did not exhibit RLS at any of the three time points. Our 12-year longitudinal study revealed significant impacts of RLS on the burden of patients with migraine.

Severe Atopic Dermatitis With Increasing Daytime Sleepiness Following Nemolizumab Administration: A Case Report

Atopic dermatitis (AD) often impairs daytime activities and quality of life (QOL) owing to intense pruritus, which disrupts sleep. Nemolizumab, an interleukin (IL)-31 receptor α inhibitor, has emerged as a promising treatment that can alleviate itching and enhance both nighttime rest and daytime functioning. We report the case of a 16-year-old boy with severe AD that was refractory to multiple therapies, including topical steroids, immunomodulators, topical Janus kinase (JAK) and phosphodiesterase 4 (PDE4) inhibitors, moisturizers, and oral antihistamines. Subcutaneous administration of nemolizumab was initiated, resulting in significant improvements in the Eczema Area and Severity Index (EASI), Patient-Oriented Eczema Measure (POEM), and Atopic Dermatitis Control Tool (ADCT) scores. However, he exhibited a marked increase in the Epworth Sleepiness Scale (ESS) the day after each injection, accompanied by pronounced daytime drowsiness lasting one to two weeks. Upon discontinuation of nemolizumab at the patient's request, daytime sleepiness resolved. Although nemolizumab is expected to reduce pruritus and improve daytime alertness, our patient exhibited paradoxical post-injection hypersomnolence. Possible contributors include shifts in the circadian rhythm or central nervous system effects related to IL-31 inhibition, although the precise mechanism is yet to be established. Therefore, careful monitoring of both dermatologic outcomes and daytime vigilance is essential. Clinicians should be aware of potential post-injection sleepiness when administering nemolizumab, given that it is an otherwise effective treatment for severe AD.

Association between iron intake and excessive daytime sleepiness in the community-dwelling Japanese: the Toon Health Study

PURPOSE

Brain iron deficiency is known to cause dopaminergic dysfunction in people with restless legs syndrome. Considering the role that dopamine plays in the wake-promoting system, we speculated that iron deficiency may contribute to the development of excessive daytime sleepiness (EDS). Therefore, we conducted the present study to examine the association between iron intake and EDS in the general population.

METHODS

We collected data from the participants of the Toon Health Study from 2009 to 2017 (N = 2405) and conducted a cross-sectional analysis. EDS was defined as an Epworth Sleepiness Scale score ≥ 11. Participants were divided into four groups according to quartiles of estimated iron intake from their responses to the Food Frequency Questionnaire. We used sex, age, body mass index, and sleep duration as adjustment variables.

RESULTS

The mean age of the participants was 57.9 years, and 64.2% were women. Compared to the highest quartile of iron intake, the multivariable-adjusted odds ratio for EDS of the lowest quartile was 1.38 (95% confidence interval [CI]: 1.04-1.83, p for trend = 0.03). When the analysis was restricted to participants with a Pittsburgh Sleep Quality Index (PSQI) score < 6, the odds ratio was 1.57 (95% CI: 1.06-2.31, p for trend = 0.04).

CONCLUSIONS

Significant inverse associations were observed between iron intake and EDS. This tendency was also observed in participants without substantial subjective sleep disturbance (i.e., PSQI score < 6), suggesting that iron deficiency may play a role in the wake-promoting system independently of sleep disturbances.

Daytime napping and depressive symptoms in bipolar disorder: A cross-sectional analysis of the APPLE cohort

BACKGROUND

The relationship between daytime napping and depression remains debatable. Thus, we investigated whether daytime napping is associated with depressive symptoms in patients with bipolar disorder.

METHODS

In a cross-sectional study, we enrolled 204 outpatients with bipolar disorder who were participants in the Association between Pathology of Bipolar Disorder and Light Exposure in Daily Life (APPLE) cohort study. Each participant's daytime napping was measured using an actigraph over 7 consecutive days. Depressive symptoms were evaluated using the Montgomery-Åsberg Depression Rating Scale, and scores of ≥8 points were considered indicative of a depressed state.

RESULTS

One-hundred and ten (53.9 %) participants were depressed. In multivariable logistic regression analysis, as the number of nap days, number of naps per day, and nap duration increased, the odds ratio (OR) for depressed state significantly increased. Additionally, compared to the participants who did not nap, the participants who napped on five or more days a week or who had an average nap duration over 60 min had more than three times higher ORs in the depressed state (number of nap days: OR, 3.66; 95 % confidence interval [CI], 1.32-10.17; nap duration: OR, 3.14; 95 % CI, 1.12-8.81).

CONCLUSIONS

We found a significant and independent association between daytime napping and depressive symptoms in patients with bipolar disorder. Further studies are warranted to identify the effect of short napping on depressive symptoms in patients with bipolar disorder.

Prevalence, dimensions, and correlates of excessive daytime sleepiness in community-dwelling older adults: the Yilan study, Taiwan

BACKGROUND

Daytime sleepiness is an important health problem. However, the dimensionality of the Epworth Sleepiness Scale (ESS) in older adults remains unclear. This study aimed to determine the prevalence of ESS-defined excessive daytime sleepiness in older adults. Furthermore, the dimensionality of ESS and its respective correlates were also compared.

MATERIALS AND METHODS

This is a community-based survey in which community-dwelling older adults aged ≥ 65 years participated. Excessive daytime sleepiness was assessed using the ESS and was defined as an ESS score of > 10. Exploratory factor analysis was performed to identify the ESS factors. Multiple logistic regression analysis was used to examine the independent correlates of the ESS-defined and factor-specific correlates of excessive daytime sleepiness.

RESULTS

In total, 3978 older adults participated in this study. The mean age was 76.6 ± 6.7 years, with 53.8% ≥ 75 years, and 57.1% were female. The prevalence of ESS-defined excessive daytime sleepiness was 16.0%. An exploratory factor analysis revealed two factors in the ESS, which were designated as 'passive' and 'active' according to the soporific levels of ESS items loaded in each factor. Multiple logistic regression showed that male, illiteracy, depression, disability, short sleep duration and no exposure to hypnotics were risk indicators for ESS-defined excessive daytime sleepiness. However, the correlates for passive and active factor-defined excessive daytime sleepiness differ in pattern, especially in variables related to education, exercise, mental health, and sleep.

CONCLUSIONS

The prevalence of ESS-defined excessive daytime sleepiness is high, and its correlates vary among older adults. This study also suggests a dual ESS structure in community-dwelling older adults.

Linguistic validation of the Epworth Sleep Scale among healthy individuals into Moroccan dialect

BACKGROUND/AIM

We performed a linguistic validation of the original version of the Epworth Sleep Scale (ESS) into the Moroccan dialect according to Guillemin's guidelines.

MATERIALS AND METHODS

After translating the English version of the ESS according to the standard guidelines, we asked 120 healthy subjects to complete the questionnaire twice with an interval of 10 days. We assess the acceptability and internal reliability by Cronbach's alpha coefficient, while for the test-retest reproducibility we use the interclass correlation coefficient (ICC) (95% confidence interval (CI)) and the kappa coefficient.

RESULTS

11-13% of subjects reported excessive sleepiness. The translated version was acceptable. A Cronbach's alpha coefficient of 0.71 and 0.70 was obtained for the entire 8-item scale on test and retest, respectively. Intra-observer reproducibility (test-retest) was satisfactory for the ESS scale with an ICC (95% CI) of 0.71 (0.618; 0.779). The kappa coefficient was 0.88, indicating excellent agreement.

CONCLUSION

These results indicate that the psychometric properties are adequate compared to the original version. Therefore, this translated version should be used to assess sleep in the Moroccan population.

Sleep Awareness of Japanese Outpatients: A Survey at a Psychiatry Department of a University Hospital

Background: Insomnia is common in patients with psychiatric disorders. However, patients' awareness of sleep has seldom been examined in detail. In this study, we investigated sleep awareness in outpatients at the psychiatry department of a university hospital. Methods: The participants (n = 241) were recruited at the psychiatry department of Ehime University Hospital between 11 October and 5 November 2021. The following questionnaires were used: Clinical Global Impression Scale of Severity (CGI-S), Global Assessment of Functioning (GAF), General Health Questionnaire (GHQ-30), Athens Insomnia Scale (AIS), and Epworth Sleepiness Scale (ESS). Psychiatric disorders were diagnosed by certified psychiatrists using the International Statistical Classification of Diseases and Related Health Problems 10. Participants with an AIS score of ≥6 were allocated to the insomnia group for statistical analysis. A logistic regression analysis was conducted to identify which items of sleep hygiene the patients with insomnia practiced using the Sleep Guidelines for Health Promotion. Results: Of 241 participants, 133 (55.2%) were allocated to the insomnia group. The mean scores for the CGI were significantly higher and the GAF scores were significantly lower in the insomnia group than in the healthy sleep group (p < 0.01). Of the 12 sleep guidelines proposed by the Japanese Government, "Do not go to bed until you are sleepful, do not delay getting up", was the item that maximally influenced insomnia. Conclusions: The insomnia group had worse scores on various medical assessment scales compared to the healthy sleep group. Based on a survey of outpatients at the psychiatry department of the university hospital, appropriate stimulus control techniques may help clinicians to treat outpatients with insomnia.

Daridorexant in Japanese patients with insomnia disorder: A phase 3, randomized, double-blind, placebo-controlled study

OBJECTIVE

This Phase 3 double-blind, placebo-controlled study evaluated the efficacy and safety of daridorexant in Japanese patients with insomnia disorder.

PATIENTS/METHODS

490 patients with insomnia disorder from 95 sites in Japan were randomized to daridorexant 50 mg (n = 163), 25 mg (n = 163) or placebo (n = 164) for 4 weeks, followed by a 7-day placebo run-out and a 30-day safety follow-up. The primary efficacy endpoints, in hierarchical order, were change from baseline at Week 4 in subjective total sleep time (sTST) and subjective latency to sleep onset (sLSO), for daridorexant 50 mg vs placebo. sTST and sLSO were also evaluated (secondary endpoints) for daridorexant 25 mg vs placebo. Safety endpoints included adverse events and next-morning sleepiness (Visual Analog Scale, VAS).

RESULTS

Daridorexant 50 mg significantly increased sTST and decreased sLSO versus placebo at Week 4 (least-squares mean difference [LSMD]: sTST 20.3 min [95 % CI 11.4, 29.2] p < 0.001; sLSO -10.7 min [-15.8, -5.5] p < 0.001). Daridorexant 25 mg also significantly improved both endpoints versus placebo (LSMD: sTST 9.2 min [0.3, 18.1] p = 0.042; sLSO -7.2 min [-12.3, -2.0] p = 0.006). Overall incidence of adverse events was similar across groups (50 mg: 22 %; 25 mg: 18 %; placebo 23 %); somnolence, the most common event, increased with increasing dose (50 mg: 6.8 %; 25 mg: 3.7 %; placebo 1.8 %). However, daridorexant did not increase VAS next-morning sleepiness. No rebound or withdrawal-related symptoms were observed after treatment discontinuation.

CONCLUSIONS

In Japanese patients with insomnia disorder, daridorexant (25 and 50 mg) was well tolerated and significantly improved subjective sleep outcomes, with no evidence of residual effects.

Morning headache caused by obstructive sleep apnea misdiagnosed as temporomandibular disorders-related headache: A case report

PATIENT

A 67-year-old woman presented to our clinic with chief complaints of headache and mandibular heaviness. Physical examination revealed bilateral tenderness in the temporalis and masseter muscles, corresponding to the patient's chief complaint. Thus, a diagnosis of temporomandibular disorders (TMDs)-related headache was made. However, sleep disorders were identified after further consultation. Hence, sleep apnea-related headache was suspected due to a snoring habit with a Mallampati classification of Class IV. Out-of-center sleep testing (OCST) revealed a respiratory event index (REI) of 10.1/h and a low peripheral oxygen saturation (SpO2) of 76%. Consequently, a diagnosis of obstructive sleep apnea (OSA) was made, and treatment using the mandibular advancement device (MAD) was recommended. Following MAD treatment, the patient's sleep quality improved, and morning headaches ceased. Subsequent OCST performed while wearing the MAD showed a significant reduction in the REI to 1.6/h and an increase in the SpO2 to 86%, indicating the therapeutic efficacy of the MAD in treating OSA.

DISCUSSION

MAD treatment effectively alleviated the patient's morning headaches, suggesting that sleep bruxism should not be considered the only cause of headaches. OSA should also be considered and addressed when investigating the potential causes of morning headaches in patients.

CONCLUSIONS

In patients experiencing TMDs symptoms and morning headaches, TMDs should not be presumed as the sole cause. Dentists should discuss the likelihood of sleep disorders during consultations. If sleep disorders are suspected, the possibility of OSA should be considered, and sleep tests should be conducted when necessary.

Plasma biomarkers of neurodegeneration in patients and high risk subjects with Lewy body disease

Comorbid Alzheimer's disease (AD) neuropathology is common in Lewy body disease (LBD); however, AD comorbidity in the prodromal phase of LBD remains unclear. This study investigated AD comorbidity in the prodromal and symptomatic phases of LBD by analyzing plasma biomarkers in patients with Parkinson's disease (PD) and dementia with Lewy bodies (DLB) and individuals at risk of LBD (NaT-PROBE cohort). Patients with PD (PD group, n = 84) and DLB (DLB group, n = 16) and individuals with LBD with ≥ 2 (high-risk group, n = 82) and without (low-risk group, n = 37) prodromal symptoms were enrolled. Plasma amyloid-beta (Aβ) composite was measured using immunoprecipitation-mass spectrometry assays. Plasma phosphorylated tau 181 (p-tau181), neurofilament light chain (NfL), and alpha-synuclein (aSyn) were measured using a single-molecule array. Plasma p-tau181 levels were higher in the PD and DLB groups than in the low-risk group. Aβ composite level was higher in the DLB group than in the high-risk group. AD-related biomarker levels were not elevated in the high-risk group. NfL levels were higher in the high-risk, PD, and DLB groups than in the low-risk group. In the PD group, Aβ composite was associated with cognitive function, p-tau181 with motor function and non-motor symptoms, and NfL with cognitive and motor functions and non-motor symptoms. In the high-risk group, NfL was associated with metaiodobenzylguanidine scintigraphy abnormalities. The PD and DLB groups exhibited comorbid AD neuropathology, though not in the prodromal phase. Elevated plasma NfL levels, even without elevated AD-related plasma biomarker levels, may indicate aSyn-induced neurodegeneration in the LBD prodromal phase.

Predicting physical and mental health status through interview-based evaluation of work stress: initial attempts to standardize the interviewing method

This study conducted an interview-based stress evaluation that considered the psychosocial models of work stress and verified the evaluation's predictive validity. A four-stage assessment comprising a pre-survey, pre-interview questionnaire, stress assessment interview, and post-survey after one month was conducted with 50 Japanese workers. Additionally, 16 occupational health professionals provided stress evaluations based on recorded interview videos. Variables based on intraclass correlation coefficients (ICCs) were computed in multiple ways to compare the agreement among the evaluators. The generalized estimating equation (GEE) was conducted to evaluate the prediction models. The overall ICC among the evaluators was 0.58. The GEE revealed that the mean score of the evaluators in the interview-based stress evaluation significantly predicted psychological symptoms (β =2.02, p=0.019), burnout (β =0.77, p<0.001), and well-being (β =-0.64, p=0.007) one month later, even after adjusting for the self-reported stress levels measured in the pre-survey. The predictive validity of the proposed interview-based stress evaluation was confirmed. Although there are several challenges in standardizing this evaluation, semi-structured interviews are an effective tool for understanding work stress.

Effect of shift work on excessive daytime sleepiness in female nurses: results from the Japan Nurses' Health Study

We investigated the relationship between shift work and excessive daytime sleepiness (EDS) among participants in the Japan Nurses' Health Study (JNHS). Responses of 9,728 female nurses to the 6th follow-up questionnaire were cross-sectionally analyzed. EDS was defined as an Epworth Sleepiness Scale score ≥11. EDS-associated factors were evaluated using Poisson regression analysis after adjustment for multiple confounders. Of the participants (mean age, 52.2 ± 8.0 yr), 28.7% were engaged in shift work, and the overall prevalence of EDS was 24.6%. EDS-associated factors were investigated separately in women aged <40 yr (n=250), 40-59 yr (n=7,467), and ≥60 yr (n=2,011). Current engagement in shift work (prevalence ratio: 1.92 [95% confidence interval: 1.20-3.06], compared with no experience of shift work) and obesity (2.08 [1.11-3.88] for BMI ≥30 and 1.39 [1.02-1.90] for BMI of 25.0-30.0, compared with BMI of 18.5-25.0) showed an independent association with EDS in women aged ≥60 yr. The effect of shift work on EDS in female nurses differed by age, as shift work and obesity contributed to EDS only in older participants. Shift work should be assigned after full consideration of age, sleep, and health status to minimize medical errors.

Effects of vibratory feedback stimuli through an oral appliance on sleep bruxism: A 14-week intervention trial

Background/purpose

Various biofeedback stimulation techniques for managing sleep bruxism (SB) have recently emerged; however, the effect of the successive application of vibratory feedback stimulation has not been clarified. This study aimed to elucidate the effect of vibration feedback stimulation via an oral appliance (OA) on SB.

Materials and methods

This prospective, single-arm, open-label intervention study included 20 participants diagnosed with "definite" SB who wore a specially designed OA for 98 nights at home. A force-based SB detection system triggered a vibrator attached to the OA. Vibratory stimulation was withheld during the first 3-week adaptation period (weeks 1-3), applied during the 9-week stimulation period (weeks 4-12), and withheld again during the post-stimulation period (weeks 13-14). The number and duration of SB events per hour of sleep were calculated based on piezoelectric signals recorded with the OA-based vibration feedback device and compared between weeks 3 and 4, 8, 12, and 14 and between weeks 12 and 14 using the Friedman test (post-hoc test with Bonferroni correction).

Results

The duration of SB events significantly decreased after vibratory stimulation (weeks 3 versus 4, 8, and 12: P < 0.001, P = 0.026, and P = 0.033, respectively) and then significantly increased upon cessation of vibratory stimulation after the stimulation period (weeks 12 versus 14: P < 0.001).

Conclusion

Contingent vibratory stimulation through an OA-based vibration feedback device may suppress SB-related masticatory muscle activity continuously for 9 weeks and may be an effective alternative for managing SB.

Bifidobacterium adolescentis SBT2786 Improves Sleep Quality in Japanese Adults with Relatively High Levels of Stress: A Randomized, Double-Blind, Placebo-Controlled Study

Sleep disorders associated with lifestyle changes and unhealthy habits are major public health concerns. Our previous study showed that Bifidobacterium adolescentis SBT2786 has a potent sleep-promoting effect on fruit flies. Fruit flies share many similarities with mammals, making them suitable model organisms for studying sleep. Thus, in the present study, we conducted a randomized, double-blind, placebo-controlled clinical trial to test whether SBT2786 has sleep-enhancing effects in humans. In this study, 61 participants in the SBT2786 group and 65 participants in the placebo group were analyzed. The results showed that SBT2786 increased sleep time; however, it predominantly increased light sleep and did not improve subjective sleep quality. Interestingly, mood improvement was observed. A subgroup analysis was conducted on participants with high stress levels, and results showed that these participants experienced an increase in sleep duration and an improvement in sleepiness upon waking up and reported feeling well-rested during the day. We concluded that SBT2786 may improve sleep quality, particularly in individuals experiencing high levels of stress, and that SBT2786 can be used as a dietary supplement to improve sleep and mood.

Assessment of Stress and Well-Being of Japanese Employees Using Wearable Devices for Sleep Monitoring Combined With Ecological Momentary Assessment: Pilot Observational Study

BACKGROUND

Poor sleep quality can elevate stress levels and diminish overall well-being. Japanese individuals often experience sleep deprivation, and workers have high levels of stress. Nevertheless, research examining the connection between objective sleep assessments and stress levels, as well as overall well-being, among Japanese workers is lacking.

OBJECTIVE

This study aims to investigate the correlation between physiological data, including sleep duration and heart rate variability (HRV), objectively measured through wearable devices, and 3 states (sleepiness, mood, and energy) assessed through ecological momentary assessment (EMA) and use of rating scales for stress and well-being.

METHODS

A total of 40 office workers (female, 20/40, 50%; mean age 40.4 years, SD 11.8 years) participated in the study. Participants were asked to wear a wearable wristband device for 8 consecutive weeks. EMA regarding sleepiness, mood, and energy levels was conducted via email messages sent by participants 4 times daily, with each session spaced 3 hours apart. This assessment occurred on 8 designated days within the 8-week timeframe. Participants' stress levels and perception of well-being were assessed using respective self-rating questionnaires. Subsequently, participants were categorized into quartiles based on their stress and well-being scores, and the sleep patterns and HRV indices recorded by the Fitbit Inspire 2 were compared among these groups. The Mann-Whitney U test was used to assess differences between the quartiles, with adjustments made for multiple comparisons using the Bonferroni correction. Furthermore, EMA results and the sleep and HRV indices were subjected to multilevel analysis for a comprehensive evaluation.

RESULTS

The EMA achieved a total response rate of 87.3%, while the Fitbit Inspire 2 wear rate reached 88.0%. When participants were grouped based on quartiles of well-being and stress-related scores, significant differences emerged. Specifically, individuals in the lowest stress quartile or highest subjective satisfaction quartile retired to bed earlier (P<.001 and P=.01, respectively), whereas those in the highest stress quartile exhibited greater variation in the midpoint of sleep (P<.001). A multilevel analysis unveiled notable relationships: intraindividual variability analysis indicated that higher energy levels were associated with lower deviation of heart rate during sleep on the preceding day (β=-.12, P<.001), and decreased sleepiness was observed on days following longer sleep durations (β=-.10, P<.001). Furthermore, interindividual variability analysis revealed that individuals with earlier midpoints of sleep tended to exhibit higher energy levels (β=-.26, P=.04).

CONCLUSIONS

Increased sleep variabilities, characterized by unstable bedtime or midpoint of sleep, were correlated with elevated stress levels and diminished well-being. Conversely, improved sleep indices (eg, lower heart rate during sleep and earlier average bedtime) were associated with heightened daytime energy levels. Further research with a larger sample size using these methodologies, particularly focusing on specific phenomena such as social jet lag, has the potential to yield valuable insights.

TRIAL REGISTRATION

UMIN-CTR UMIN000046858; https://center6.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000053392.

Changes in the Objective Measures of Sleep in Association with Menses Among Female Athletes with Poor Subjective Sleep Quality: Female Athletes with Poor Subjective Sleep Quality Have More Sleep Arousals During Menses

Purpose

Female athletes with menstrual abnormalities have poor sleep quality. However, whether female athletes with poor sleep quality based on subjective assessment have distinctive changes in objective measures of sleep in association with menses remains unclear. This study aimed to compare changes in objective sleep measurements during and following menses between collegiate female athletes with and without poor subjective sleep quality.

Patients and Methods

Female collegiate athletes (age range/mean ± standard deviation: 18-22/ 22.2±1.1) with regular menstrual cycles were recruited. The participants underwent home electroencephalogram monitoring during the first and second nights after the onset of menses and one night between the seventh and 10th nights after menses onset (mid-follicular phase). The Pittsburgh Sleep Quality Index (PSQI) was used to assess the subjective sleep quality. Interactions between the presence of poor subjective sleep quality (ie, PSQI ≥6) and changes in objective measures of sleep in association with menses were analyzed.

Results

Data of 45 athletes, including 13 with poor subjective sleep quality, showed that changes in arousal index in athletes with poor subjective sleep quality were distinctive from those in athletes without poor subjective sleep quality (p = 0.036 for interaction). In athletes with poor subjective sleep quality, the arousal index was significantly increased in menses (p for analysis of variance, 0.015), especially on the first night after the onset of menses compared with during the mid-follicular phase (p = 0.016).

Conclusion

Collegiate female athletes with regular menstrual cycles are likely to have poor subjective sleep quality in association with more frequent arousal during the first night after the onset of menses than during the mid-follicular phase.

Associations between the burdens of comorbid sleep problems, central sensitization, and headache-related disability in patients with migraine

Objective

Sleep disturbances are common in migraine patients and affect quality of life. Central sensitization (CS) is likely to play a role in the increased severity and chronicity of migraine. We hypothesized that the number of comorbid sleep problems would affect headache-related disability through the effects of central sensitization (CS).

Methods

We performed a cross-sectional study including 215 consecutive patients with migraine. Insomnia was defined as a Pittsburgh Sleep Quality Index (PSQI) global score greater than 5. Probable REM sleep behavior disorder (pRBD) was defined as an RBD screening score of 5 or greater. Excessive daytime sleepiness (EDS) was defined as an Epworth Sleepiness Scale score of 10 or higher. Suspected sleep apnea (SA) was defined as patients with snoring or sleep apnea witnessed 3 or more nights a week. CS was assessed by the Central Sensitization Inventory (CSI).

Results

Restless legs syndrome, insomnia, EDS, SA and pRBD were observed in 25.6%, 71.6%, 34.4%, 10.2%, and 21.4%, respectively, of the patients. At least one sleep problem was present in 87.0% of the patients. According to the results of the multinomial logistic regression analysis with no sleep problems as a reference, after we corrected for adjustment factors, the Migraine Disability Assessment (MIDAS) score significantly increased when three or more comorbid sleep problems were present. According to our mediation analysis, an increased number of sleep problems had a direct effect on the MIDAS score after we adjusted for other variables, and the CSI score was indirectly involved in this association.

Conclusion

The present study showed an association between migraine-related disability and the burden of multiple sleep problems, which was partially mediated by CS.

Comparison of sleep characteristics between Parkinson's disease with and without freezing of gait: A systematic review

Parkinson's disease (PD) is a neurodegenerative disorder characterized by a range of motor and non-motor symptoms. Among the motor complaints, freezing of gait (FOG) is a common and disabling phenomenon that episodically hinders patients' ability to produce efficient steps. Concurrently, sleep disorders are prevalent in PD and significantly impact the quality of life of affected individuals. Numerous studies have suggested a bidirectional relationship between FOG and sleep disorders. Therefore, our objective was to systematically review the literature and compare sleep outcomes in PD patients with FOG (PD + FOG) and those without FOG (PD-FOG). By conducting a comprehensive search of the PubMed and Web of Science databases, we identified 20 eligible studies for inclusion in our analysis. Our review revealed that compared to PD-FOG, PD + FOG patients exhibited more severe symptoms of rapid eye movement sleep behavior disorder in nine studies, increased daytime sleepiness in eight studies, decreased sleep quality in four studies, and more frequent and severe sleep disturbances in four studies. These findings indicate that PD + FOG patients generally experience worse sleep quality, higher levels of daytime sleepiness, and more disruptive sleep disturbances compared to those without FOG (PD-FOG). The association between sleep disturbances and FOG highlights the importance of evaluating and monitoring these symptoms in PD patients and open the possibility for future studies to assess the impact of managing sleep disturbances on the severity and occurrence of FOG, and vice versa.

Assessment of cognitive function and sleep-wake rhythms in community-dwelling older adults

Disruption of the circadian rhythm and sleep-wake cycles is a consequence of aging and is associated with the cognitive decline and many neurodegenerative conditions. We investigated the bedtime, wake-up time, sleep timing (midpoint between bedtime and wake-up time), and sleep timing standard deviation (SD) using the actigraphy among 80 consecutive volunteers aged ≥ 60 years. Global cognitive function and executive function of detailed cognitive domains were evaluated using the mini-mental state examination (MMSE) and Wisconsin card sorting test (WCST) and subjective daytime sleepiness was assessed using the Epworth Sleepiness Scale (ESS). The category achievement (CA), total errors (TE), perseverative errors of Nelson (PEN), non-perseverative errors (NPE), and difficulties in maintaining set (DMS) on the WCST were significantly correlated with sleep timing SD (CA: r = - 0.276, p = 0.013, TE: r = 0.311, p = 0.005, PEN: r = 0.241, p = 0.032, NPE: r = 0.250, p = 0.025, DMS: r = 0.235, p = 0.036), but not with the MMSE score. Multiple regression analyses with the stepwise forward selection method including age, ESS score, bedtime, sleep timing, and sleep timing SD, revealed that the ESS score, and sleep timing SD were significant factors related to CA on the WCST (ESS score: β = - 0.322, p = 0.004; sleep timing SD: β = - 0.250, p = 0.022). Assessment of sleep-wake rhythms, daytime sleepiness, and cognitive function using the MMSE and WCST is valuable for the prediction of cognitive decline in the geriatric population.

Different dimensions of daytime sleepiness predicted mortality in older adults: Sex and muscle power-specific risk in Yilan Study, Taiwan

OBJECTIVES

This study aimed to investigate the relationship between daytime sleepiness and mortality risk among older adults. The moderating effects of sex and physical function were examined.

METHODS

This 9-year follow-up study was conducted with community-dwelling individuals aged ≥65 years. Daytime sleepiness was evaluated using the Epworth Sleepiness Scale (ESS). Exploratory factor analysis (EFA) was used to examine the ESS factors. Handgrip strength was measured to assess physical function, and the highest quartile was defined as good muscle power. Cox regression analysis was used to estimate the 9-year all-cause mortality risk. The interaction terms were examined to evaluate their moderating effect.

RESULTS

In total, 2588 individuals participated in the study. The EFA explored two factors: the passive factor (PF) and the active factor (AF). After controlling for various covariates, the cutoff-defined daytime sleepiness (ESS≥11), total raw scores, and factor scores of the ESS all failed to predict mortality risk. The 3-way interaction terms showed statistical significance in terms of [sex × PF × muscle power (p = 0.03)] but not for [sex × AF × muscle power (p = 0.11)]. Specifically, PF predicted mortality risk in women with good muscle power (hazard ratio (HR): 1.48; 95 % confidence interval (CI): 1.04-2.10), which is female-specific. In contrast, AF predicted mortality risk only in men with good muscle power (HR: 1.35; 95 % CI: 1.02-1.78).

CONCLUSIONS

The ESS-measured daytime sleepiness in older adults is multidimensional. The mortality risk for each dimension was determined based on sex and physical function.

Successful Challenge With Brexpiprazole for Idiopathic Hypersomnia in a Patient With Bipolar Disorder: A Case Report

We describe a 32-year-old Japanese female with hypersomnia and bipolar disorder. She had developed hypersomnia and sleep attacks in her teens. She was misdiagnosed with narcolepsy at a neurology department and then received methylphenidate (MPH) for many years. After giving birth, she developed postpartum depression and suffered from mood swings and irritability. Following 10-year treatment with methylphenidate, she experienced MPH-induced psychosis when she was in a manic state. Her psychosis improved rapidly with the cessation of methylphenidate. Furthermore, brexpiprazole treatment ameliorated her manic symptoms and hypersomnolence. Post-discharge, she was diagnosed with idiopathic hypersomnia based on nocturnal polysomnography and a multiple sleep latency test. This case indicates that brexpiprazole as a serotonin dopamine activity modulator might provide therapeutic effects against not only the patient's manic symptoms but also idiopathic hypersomnia.

Prevalence of excessive daytime sleepiness and its association with daily life factors in Japanese first-year university students

As lifestyles have shifted to favor nighttime activities, daytime sleepiness and sleep-related problems have become increasingly common in Japan. Excessive daytime sleepiness (EDS) is an adverse consequence of sleep loss and an important public health concern. EDS may cause academic difficulties, behavioral abnormalities, and psychological dysfunction; therefore, it is a particularly important issue among university students. We conducted a cross-sectional study to investigate the prevalence of EDS and its associated lifestyle factors among Japanese university students. A questionnaire was completed by 1470 first-year university students, aged 19.0 (± 1.0) years. Using the questionnaire, we collected information on (1) demographic variables, (2) lifestyle variables, and (3) sleep habits and daytime sleepiness. Daytime sleepiness was measured using the Japanese version of the Epworth Sleepiness Scale, a frequently used subjective scale for assessing sleepiness. The overall prevalence of EDS was 57% (53% in men and 61% in women). Multivariate logistic regression analysis revealed that the following factors were associated with EDS: female sex, exercise habits, long commuting times, later wake-up times, and shorter sleep duration. Given that more than 50% of first-year university students reported having EDS, interventions should be considered to decrease its risk, including educational programs that provide strategies to extend sleep duration and delay wake-up time. Such strategies may also be valuable for students with other potential risk factors, such as exercise habits or long commute times, that are associated with EDS.

Impact of diabetes and glycated hemoglobin level on the clinical manifestations of Parkinson's disease

BACKGROUND

The coexistence of diabetes mellitus (DM) has been suggested to accelerate the progression of Parkinson's disease (PD) and make the phenotype more severe. In this study, we investigated whether DM or glycated hemoglobin (HbA1c) levels affect the differences in motor and nonmotor symptoms.

METHODS

We conducted a cross-sectional study including 140 consecutive Japanese patients with PD for whom medical history and serum HbA1c records were available. The PD patients with a DM diagnosis were classified into the diabetes-complicated group (PD-DM) and the nondiabetes-complicated group (PD-no DM). Next, patients were classified based on a median HbA1c value of 5.7, and clinical parameters were compared. The correlations between HbA1c levels and other clinical variables were analyzed.

RESULTS

Of 140 patients, 23 patients (16%) had DM. Compared to PD-no DM patients, PD-DM patients showed lower MMSE scores. Compared to the lower HbA1c group, the higher HbA1c group showed a higher MDS-UPDRS part III score and a lower metaiodobenzylguanidine (MIBG) scintigraphy heart-to-mediastinum (H/M) ratio. HbA1c levels were positively correlated with age and the MDS-UPDRS part III score and negatively correlated with the MMSE score and H/M ratio on cardiac MIBG scintigraphy. Binary logistic regression analysis, which included age, sex, disease duration, and MMSE and MDS-UPDRS part III scores as independent variables, revealed that a lower MMSE score was an independent contributor to PD-DM and PD with high HbA1c levels.

CONCLUSIONS

DM complications and high HbA1c levels may affect cognitive function in patients with PD.

Assessment of the Brazilian Version of the Epworth Sleepiness Scale Using Item Response Theory: A Psychometric Study

There seems to be a consensus that adolescents worldwide are not getting enough sleep. This study aimed to evaluate the psychometric properties of the Epworth Sleepiness Scale (ESS) in adolescents using the item response theory. A psychometric study was conducted with 2206 adolescents aged 18 and 19 years in the city of São Luís, Maranhão, Brazil. The dimensionality of the ESS was assessed by principal component analysis. A Samejima's graded response model (SGRM) was fitted to it. The findings of this study showed a good internal consistency and the unidimensionality of the ESS. Considering the latent trait continuum, we obtained three levels, with anchor items. For the item 'Sitting still in a public place', the adolescents presented a small possibility of dozing in level 1, and a medium and great possibility in level 2. The item 'Sitting around talking to someone' presented small, medium, and great possibilities of dozing in level 3. The ESS with five items showed satisfactory psychometric properties. In addition, the results from the SGRM showed that adolescents with high levels of sleepiness are likely to nod off or sleep sitting up while talking to someone. This study allows us to understand excessive daytime sleepiness in adolescents.

Epworth sleepiness scale: A meta-analytic study on the internal consistency

OBJECTIVE/BACKGROUND

The Epworth Sleepiness Scale (ESS) is one of the most used self-reported instruments to assess sleepiness. Thus, several adaptations into different Languages have been performed worldwide over the years. The scale has produced disparate psychometric properties when applied in different settings. In the current study, our aim was to perform a Reliability Generalization meta-analysis of the Cronbach᾽s alphas of all published studies on ESS, specifically with a psychometric focus.

PATIENTS/METHODS

Three reference databases (Scopus, PubMed and Web of Science) were searched since 1991 to October 2022 and all the records on psychometric or validation studies that reported Cronbach's alphas, from clinical and nonclinical groups, were included. In total, data from 46 publications (63 estimates) were extracted, comprising 92,503 participants.

RESULTS

Using a Random-Effects Model, the cumulative Cronbach's alpha for the 63 estimates was about 0.82 (CI: 0.798, 0.832) which can be considered as a good measure. However, and as expected, it was observed a high level of heterogeneity (I2 = 98.96%). Moderation analyses considering setting, date, continent, risk of bias, sex, age and language were performed in order to account for the heterogeneity. Even so, only the variables study setting and continent were significant, and had little importance in explaining the heterogeneity.

CONCLUSIONS

The ESS is a reliable tool to measure sleepiness; however, further studies are needed to investigate what variables might explain the observed variability. Moreover, it will be important to include empirical studies beyond psychometric ones.

Residual excessive daytime sleepiness in patients with sleep apnea syndrome receiving continuous positive airway pressure in Japan: A single-center study

Excessive daytime sleepiness (EDS) is a symptom of sleep apnea syndrome (SAS). In some patients with SAS who undergo continuous positive airway pressure (CPAP) therapy, EDS persists (residual EDS). However, knowledge of residual EDS in Japan is limited. Therefore, we examined EDS as defined by the Japanese version of the Epworth Sleepiness Scale (a score of ≥11) before and after long-term (≥1 year) CPAP therapy in 490 patients with SAS. Good adherence to CPAP therapy was defined as its use for at least 4 h during 70% of the nights. The prevalence of residual EDS was 9.4%. Residual EDS was negatively associated with good adherence to CPAP therapy. Furthermore, the longer the CPAP therapy duration after initiation, the lower the prevalence of residual EDS. Therefore, the findings on the prevalence of residual EDS and its association with CPAP therapy in Japan are probably similar to those of other countries.

Reliability and validity of the Japanese version of the Ullanlinna Narcolepsy Scale and Swiss Narcolepsy Scale for screening Japanese individuals with narcolepsy type 1

OBJECTIVE

To validate the Japanese versions of the Ullanlinna Narcolepsy Scale (J-UNS) and Swiss Narcolepsy Scale (J-SNS) for screening narcolepsy in the Japanese population and to discuss strategies for their use in hypersomniac individuals.

METHODS

We selected 451 outpatients with excessive daytime sleepiness (EDS) already diagnosed according to the International Classification of Sleep Disorders third edition. They responded to both scales twice at 1-month intervals. After eliminating individuals who met the exclusion criteria, validity and reliability analyses were performed on 408 and 381 participants, respectively.

RESULTS

Patients with narcolepsy type 1 (NT1) displayed higher J-UNS and lower J-SNS scores than those with NT2 and other sleep disorders. The intraclass correlation coefficients and weighted κ coefficient for scale scores in the total participants and patients with NT1 were ≥0.70 and ≥ 0.40, respectively, indicating high reliability. Furthermore, both the sensitivity and specificity of these scales upon using the original cut-off scores (14 for UNS and 0 for SNS) for detecting NT1 were 0.70 or ≥0.70, suggesting high validity. Additionally, the receiver operating characteristic curve analysis revealed that the best cut-off score did not change for the J-SNS but that for the J-UNS, it increased to 18. In our study, the scale's sensitivity and specificity changed from 96% to 82% and 58%-78%, respectively.

CONCLUSIONS

Both scales revealed satisfactory screening abilities for NT1 in the Japanese population. However, it may be better to use J-UNS cut-off scores of 18 for a population with EDS.

Better Mental Health and Sleep under Behavioral Restrictions Due to COVID-19 in Japanese University Students: A Cross-Sectional Survey

Coronavirus disease (COVID-19) is a global pandemic, which is not only a severe public health issue but also significantly impacts the physical activity, sleep habits, and mental health of university students. Thus, we examined the association between behavioral restrictions due to COVID-19 and sleep patterns and mental health in first-year Japanese university students. Four hundred and twenty-two students (253 males and 169 females; age, 18.7 ± 1.0 years) participated in our questionnaire study. Under the behavioral restrictions due to COVID-19, 193 students (127 males and 66 females) responded to the questionnaire online from home. The participants did not visit the university during the survey period. The data acquired the year before the COVID-19 pandemic (2018 and 2019) were used as control data (126 males and 103 females). The questionnaire consisted of four sections: (1) demographic and lifestyle variables, (2) the Pittsburgh Sleep Quality Index, (3) the Japanese version of the Epworth Sleepiness Scale, and (4) the Patient Health Questionnaire-9. Our data revealed that self-restraint due to COVID-19 was associated with better sleep and mental health. In addition, mental health was independent of sleep, while sleep was related to mental health. These differences were more pronounced in male than in female students. This finding could be due to physical activity at night, part-time work, and long commuting times during the pre-pandemic period.

Development and validation of the Japanese version of the Restorative Sleep Questionnaire in community samples

OBJECTIVE

This study aimed to validate the Japanese version of the Restorative Sleep Questionnaire Weekly version (RSQ-W-J) and estimate the RSQ-W-J cut-off score to identify the degree of non-restorative sleep (NRS) that interferes with daytime function.

METHODS

An online survey was conducted, and 513 participants (241 men, 272 women; mean age, 47.88 ± 16.66 years) completed the questionnaires. The RSQ-W-J, Multidimensional Fatigue Inventory, Athens Insomnia Scale, Patient Health Questionnaire-9, Epworth Sleepiness Scale, Sleep Debt Index, NRS and the degree of daytime dysfunction, and the diagnostic criteria for chronic insomnia were used as implementation scales.

RESULTS

The RSQ-W-J was confirmed to have a single-factor structure. Both the Cronbach α coefficient and test-retest reliability of RSQ-W-J were high (α = 0.91; intraclass correlation coefficient [ICC]_agreement = 0.85). The RSQ-W-J was significantly negatively correlated with the scales of fatigue, insomnia, depressive symptoms, daytime sleepiness, and sleep debt. In addition, the RSQ-W-J scores of the insomnia group, in which participants met the diagnostic criteria for chronic insomnia, NRS group, in which participants had NRS only, and sleep debt group, in which participants had sleep debt, were significantly lower than those in the normal sleep group. Furthermore, the insomnia group scored significantly lower than the sleep debt group. The RSQ-W-J cut-off score, which indicates whether or not NRS interferes with daytime function, was estimated to be 45.8 points.

CONCLUSIONS

The RSQ-W-J was shown to be useful for comprehensively measuring the degree of restorative sleep.

Clinico-imaging features of subjects at risk of Lewy body disease in NaT-PROBE baseline analysis

Individuals with prodromal symptoms of Lewy body disease (LBD), such as rapid eye movement sleep behavior disorder (RBD), often showed imaging defects similar to patients with Parkinson's disease and dementia with Lewy bodies. We examined dopamine transporter (DaT) single-photon-emission computed tomography (SPECT) and metaiodobenzylguanidine (MIBG) scintigraphy in 69 high-risk subjects with ≥2 prodromal symptoms (dysautonomia, hyposmia, and probable RBD) and 32 low-risk subjects without prodromal symptoms, whom were identified through a questionnaire survey of health checkup examinees. The high-risk subjects had significantly worse scores on Stroop test, line orientation test, and the Odor Stick Identification Test for Japanese than the low-risk subjects. The prevalence of abnormalities on DaT-SPECT was higher in the high-risk group than in the low-risk group (24.6% vs. 6.3%, p = 0.030). A decreased uptake on DaT-SPECT was associated with motor impairment, and MIBG scintigraphy defects were associated with hyposmia. The simultaneous evaluation of DaT-SPECT and MIBG scintigraphy may capture a wide range of individuals with prodromal LBD.

Fatigue on Waking, Insomnia, and Workplace Relationship Problems May Help to Detect Suicidal Ideation among New Middle-Aged Primary Care Patients: A 6-Month Prospective Study in Japan

Signs of suicidal depression often go undetected in primary care settings. This study explored predictive factors for depression with suicidal ideation (DSI) among middle-aged primary care patients at 6 months after an initial clinic visit. New patients aged 35-64 years were recruited from internal medicine clinics in Japan. Baseline characteristics were elicited using self-administered and physician questionnaires. DSI was evaluated using the Zung Self-Rating Depression Scale and the Profile of Mood States at enrollment and 6 months later. Multiple logistic regression analysis was conducted to calculate adjusted odds ratios for DSI. Sensitivity, specificity, and likelihood ratios for associated factors were calculated. Among 387 patients, 13 (3.4%) were assessed as having DSI at 6 months. Adjusted for sex, age, and related factors, significant odds ratios for DSI were observed for "fatigue on waking ≥1/month" (7.90, 95% confidence intervals: 1.06-58.7), "fatigue on waking ≥1/week" (6.79, 1.02-45.1), "poor sleep status" (8.19, 1.05-63.8), and "relationship problems in the workplace" (4.24, 1.00-17.9). Fatigue on waking, sleep status, and workplace relationship problems may help predict DSI in primary care. Because the sample size in this investigation was small, further studies with larger samples are needed to confirm our findings.

The simplification of the insomnia severity index and epworth sleepiness scale using machine learning models

Insomnia and excessive daytime sleepiness (EDS) are the most common complaints in sleep clinics, and the cost of healthcare services associated with them have also increased significantly. Though the brief questionnaires such as the Insomnia Severity Index (ISI) and Epworth Sleepiness Scale (ESS) can be useful to assess insomnia and EDS, there are some limitations to apply for large numbers of patients. As the researches using the Internet of Things technology become more common, the need for the simplification of sleep questionnaires has been also growing. We aimed to simplify ISI and ESS using machine learning algorithms and deep neural networks with attention models. The medical records of 1,241 patients who examined polysomnography for insomnia or EDS were analyzed. All patients are classified into five groups according to the severity of insomnia and EDS. To develop the model, six machine learning algorithms were firstly applied. After going through normalization, the process with the CNN+ Attention model was applied. We classified a group with an accuracy of 93% even with only the results of 6 items (ISI1a, ISI1b, ISI3, ISI5, ESS4, ESS7). We simplified the sleep questionnaires with maintaining high accuracy by using machine learning models.

Idiopathic Central Alveolar Hypoventilation wherein Sleep Disordered Breathing Was Considered Well-controlled by the Continuous Positive Airway Pressure Tracking System but Not Controlled by Polysomnography

A 54-year-old man whose awake percutaneous arterial oxygen saturation (SpO2) was 94% was diagnosed with obstructive sleep apnea by polysomnography (PSG). His apnea-hypopnea index (AHI) was 138.8 (AI: 4.7 and HI: 134.1), so he was treated with continuous positive airway pressure (CPAP), and his condition was considered well-controlled by the CPAP tracking system (AHI=3.4), with improvement seen in his symptoms when he left our hospital. However, he returned to our hospital 4 years later with recurrent sleepiness and hypercapnia despite the well-controlled status (AHI=3.8) according to the tracking system. His hypercapnia improved following voluntary hyperventilation. Idiopathic central alveolar hypoventilation was diagnosed, with the AHI considered to be well-controlled by the CPAP tracking system but not at all according to PSG.

French Sleepiness Scale for Adolescents-8 items: A discriminant and diagnostic validation

The objective of the present study was to validate the Short Version of French Sleepiness Scale for Adolescents (FSSA) with eight items (FSSA8).

METHODS

A total of 384 adolescents, aged between 12 and 18 years, completed the FSSA8. These included 269 nonclinical adolescents and 115 adolescents admitted for overnight polysomnography and Multiple Sleep Latency Test (MSLT) because of suspected hypersomnia (85 patients with narcolepsy and 30 with other sleep disorders). Item response theory (IRT) assumptions were tested and psychometric properties were analysed. Matching on sex ratio and age was conducted to estimate concurrent criterion, diagnostic validity and cut-offs.

RESULTS

IRT assumptions were validated confirming the one-dimensionality of the FSSA8. The latent continuum sleepiness for which the scale and its items are reliable encompassed most of the clinical subjects. FSSA8 is weakly correlated with MSLT. Distribution of scores for the nonclinical group and the clinical group differed significantly; the FSSA8 had very good screening validity in sleep disorders. The cut-off was seven points.

CONCLUSION

The FSSA8 appeared to be more reliable for patients than for nonclinical participants and to be a good tool for screening excessive daytime sleepiness in sleep disorders.

Analysis of the effect of brexpiprazole on sleep architecture in patients with schizophrenia: A preliminary study

BACKGROUND

Brexpiprazole is an atypical antipsychotic drug widely used in Japan for the treatment of schizophrenia. Previous studies have investigated the therapeutic effects of some antipsychotics on sleep variables; however, to our knowledge, the effects of brexpiprazole on sleep architecture have not been examined in patients with schizophrenia. Therefore, we aimed to exploratorily investigate the effect of brexpiprazole on sleep variables measured by polysomnography in patients with schizophrenia.

METHODS

This study included 10 patients with schizophrenia who were originally treated with haloperidol alone. Sleep variables of the participants were measured using polysomnography. After excluding those who did not meet the study criteria, seven patients (five men and two women; mean age [SD], 59.0 [10.0] years) were eligible for further analysis. Polysomnography was repeated at 4 weeks after the participants were prescribed brexpiprazole in addition to haloperidol. We compared the sleep architecture of the participants, measured using polysomnography, before and after taking brexpiprazole.

RESULTS

Add-on brexpiprazole significantly prolonged rapid eye movement latency, increased the duration and percentage of stage N2 and stage N3 sleep (min, %), and decreased the duration and percentage of stage rapid eye movement sleep (min, %) at a significance level of nominal p < 0.05.

CONCLUSION

Although not significant after correcting for multiple comparisons, the present results showed that add-on brexpiprazole could alter the sleep architecture of patients with schizophrenia. Future studies are warranted to replicate these findings and to further investigate the beneficial influence of brexpiprazole on sleep.

Delayed sleep-wake rhythm due to staying at home during the COVID-19 pandemic and sleep debt after returning to campus among Japanese nursing university students: A longitudinal study

This study aimed to investigate sleep problems during staying at home due to the coronavirus disease 2019 (COVID-19) pandemic and after returning to campus among university nursing students. We analyzed data from self-reported sleep surveys conducted during a nursing course at a university in Tokyo between 2019 and 2021. During staying at home due to COVID-19, we observed delayed sleep-wake rhythm, prolonged sleep duration on weekdays, a decreased sleep debt, improved daytime sleepiness, and worsened insomnia, especially in terms of difficulty initiating sleep (Study 1; 18 paired data). After returning to campus, we found advanced wake-up time, shortened sleep duration, increased sleep debt, worsened insomnia, and increased daytime sleepiness (Study 2; 91 paired data). The association between advanced midpoint of sleep and commute time over an hour (aOR, 3.29; 95%CI: 1.24-8.72) was confirmed. Furthermore, sleep paralysis and nightmares were more prevalent among nursing students with an advanced midpoint of sleep, whereas nursing students whose midpoint of sleep was delayed had higher daytime sleepiness after returning to campus. To maintain regular sleep-wake rhythms and sufficient sleep duration, the educational environment surrounding nursing university students (e.g., curriculum, class schedule, style of class) should be established considering their age-dependent biological rhythm in addition to sleep hygiene education for students.

Polysomnographic and Clinical Parameters before and after Zonisamide Therapy for Parkinson's Disease

Objective Sleep disturbance is a common nonmotor symptom associated with a decreased quality of life in patients with Parkinson's disease (PD). In this study, we evaluated the effects of zonisamide on motor and non-motor symptomology in patients with PD, especially with respect to objective sleep assessments conducted via polysomnography. Methods We conducted a 12-week, open-label study to assess the effects of zonisamide. The patients received 25 mg/day of zonisamide and underwent overnight polysomnography prior to and after 12 weeks of zonisamide treatment. They were assessed for their cognitive function (Mini-Mental State Examination and the Japanese version of the Montreal Cognitive Assessment), gait function (Timed Up-and-Go Test, 10-m Gait Walk Test), Parkinson's symptomology (Movement Disorder Society Revision of the Unified Parkinson's Disease Rating Scale parts 2 and 3), and self-reported sleep (Epworth Sleepiness Score, Parkinson's Disease Sleep Scale-2). Results Six patients completed the study. Polysomnographic data revealed a statistically significant increase in the percentage of time spent in sleep stage N2 (10.8%±9.2%, p=0.031) and a declining trend in the percentage of time spent in sleep stage N1 (-8.9%±12.7%, p=0.063). Although none of the patients had sleep stage N3 at baseline, 3 of the 6 patients experienced sleep stage N3 (1.1-5.4%) after 12 weeks of zonisamide treatment. The other polysomnographic parameters and clinical scores showed no statistically significant differences. Conclusions This preliminary study demonstrated that zonisamide improved objective sleep parameters measured by polysomnography in patients with PD.

Decreased psychomotor vigilance is a risk factor for motor vehicle crashes irrespective of subjective daytime sleepiness: the Toon Health Study

STUDY OBJECTIVES

Although excessive daytime sleepiness (EDS) has a crucial impact on motor vehicle crashes (MVCs), the assessment of subjective sleepiness as a screening tool for MVC has limitations. Objective daytime sleepiness may be a better predictor of MVCs rather than subjective daytime sleepiness. Therefore, we aimed to examine the association of psychomotor vigilance as a surrogate marker of objective sleepiness and subjective sleepiness with MVCs in a prospective cohort study of the general population.

METHODS

The study participants were 903 community-dwelling Japanese followed up 5 years after baseline and ascertained history of MVC over the study period. Psychomotor vigilance was measured by the psychomotor vigilance test and categorized into quartiles by the reciprocal of the mean reaction time (mean1/RT). Subjective EDS was defined using the Japanese version of the Epworth Sleepiness Scale. Multivariable logistic regression analysis was used to examine the association between mean1/RT and MVC after stratification by subjective EDS.

RESULTS

The multivariable-adjusted odds ratio (95% confidence interval) for MVC among the highest quartile group of mean1/RT was 0.31 (0.17-0.57), compared with the lowest group (P for trend < .01). After stratification by subjective EDS, the significant association was found only among the nonsubjective EDS group (P for trend < .01) and not among the subjective EDS group (P for trend = .16).

CONCLUSIONS

Decreased psychomotor vigilance measured by the psychomotor vigilance test was associated with a higher risk of MVCs, and the association was more evident among the nonsubjective EDS group. The psychomotor vigilance test may be useful to prevent sleep-related MVCs in the general population, particularly for individuals without subjective EDS.

CITATION

Matsuo R, Tanigawa T, Oshima A, et al. Decreased psychomotor vigilance is a risk factor for motor vehicle crashes irrespective of subjective daytime sleepiness: the Toon Health Study. J Clin Sleep Med. 2023;19(2):319-325.

Factors contributing to sleep disturbances and excessive daytime sleepiness in patients with Parkinson's disease

Background

Sleep disturbances and excessive daytime sleepiness (EDS) are common non-motor symptoms in patients with Parkinson's disease (PD). The purpose of this study was to identify the contributors to sleep disturbances, including insomnia, restless legs syndrome, rapid eye movement sleep behavior disorder (RBD), sleep-disordered breathing, nocturnal akinesia and EDS, in patients with PD.

Methods

We conducted a cross-sectional study including 128 consecutive Japanese patients with PD. Sleep disturbances and EDS were defined as a PD Sleep Scale-2 (PDSS-2) total score ≥15 and an Epworth Sleepiness Scale (ESS) score >10, respectively. The patients were divided into four groups according to the presence or absence of sleep disturbances and EDS. We evaluated the disease severity, motor symptoms, cognition, olfactory test, the Scales for Outcomes in PD-Autonomic dysfunction (SCOPA-AUT), the Beck Depression Inventory-II (BDI-II), and the RBD Screening Questionnaire Japanese version (RBDSQ-J).

Results

Of 128 patients, 64 had neither EDS nor sleep disturbances, 29 had sleep disturbances without EDS, 14 had EDS without sleep disturbances, and 21 had both EDS and sleep disturbances. Patients with sleep disturbances had higher BDI-II scores than those without sleep disturbances. Probable RBD was more frequent in patients with both sleep disturbances and EDS than in those with neither EDS nor sleep disturbances. The SCOPA-AUT score was lower in patients with neither EDS nor sleep disturbances than in patients in the other three groups. Using multivariable logistic regression analysis with neither sleep disturbances nor EDS as a reference group, that the SCOPA-AUT score was an independent contributor to sleep disturbances (adjusted OR, 1.192; 95% CI, 1.065-1.333; P = 0.002) or EDS (OR, 1.245; 95% CI, 1.087-1.424; P = 0.001) and that the BDI-II (OR, 1.121; 95% CI, 1.021-1.230; P = 0.016) and RBDSQ-J scores (OR, 1.235; 95% CI, 1.007-1.516; P = 0.043) as well as the SCOPA-AUT score (OR, 1.137; 95% CI, 1.006-1.285; P = 0.040) were independent contributors to both sleep disturbances and EDS.

Conclusions

Autonomic symptoms were associated with patients with sleep disturbances or EDS, and depressive and RBD symptoms in addition to autonomic symptoms were associated with patients with both sleep disturbances and EDS.

Characteristics of sleep-disordered breathing in children with down syndrome - A comparison with typically developing children

Background

Compared with typically developing control children (CC), children with Down syndrome (DS) frequently exhibit sleep-disordered breathing (SDB) and unusual sleep postures (USPs). No studies have directly compared SDB-related signs and symptoms, SDB-related parameters, and USPs between children with DS and CC. This study aimed to evaluate the prevalences of SDB and USPs in children with DS and CC.

Methods

We analyzed SDB-related parameters measured via overnight pulse oximetry and questionnaires administered to parents on SDB-related signs and symptoms, including sleeping postures. Estimated SDB was defined as a 3% oxygen desaturation index (ODI) ≥5 dips/h.

Results

Fifty-one children with DS (4–5 years: N = 12, 6–10 years: N = 23, 11–15 years: N = 16) and sixty-three CC (4–5 years: N = 18, 6–10 years: N = 27, 11–15 years: N = 18) were included. The prevalence of estimated SDB and observed USPs was higher in children with DS than in CC (p < 0.0001). Among children aged 11–15 years old, but not those aged 4–5 and 6–10 years old, frequency of arousal and apnea (p = 0.045 and p = 0.01, respectively) were higher in children with DS than in CC. Multivariate analyses showed that DS was associated with SDB-related signs and symptoms, estimated SDB, 3% ODI, average oxygen saturation (SpO₂), and nadir SpO₂, while USPs were associated only with higher values of SpO₂ <90%.

Conclusions

Estimated SDB tended to increase in children with DS but decreased in CC with growth. USPs were more frequent in children with DS than in CC, especially in older children. USPs might indicate severe hypoxemia due to SDB in DS.

•

The difference of prevalence of SDB/USPs between DS and CC was evaluated.

•

The prevalence of SDB increased with growth in the DS but not in the CC.

•

USPs, taking to escape from suffocation by SDB, were frequently observed in older DS.

Sleep-related hallucinations in patients with Parkinson's disease

Given that sleep-wake cycle dysfunction can cause hallucinations in Parkinson's disease patients, sleep-related hallucinations may be a different subtype from hallucinations that occur only during full wakefulness. However, few studies that distinguish the onset situations of hallucinations related to sleep from those that occur in full wakefulness have been conducted to investigate hallucinations in Parkinson's disease patients. Therefore, we conducted a multicenter observational study to investigate the prevalence of and factors associated with sleep-related hallucinations in patients with Parkinson's disease. Information on hallucinations was collected by using a questionnaire and face-to-face interviews. Of 100 consecutive patients with Parkinson's disease, 29 (29%) reported sleep-related hallucinations, and 16 (16%) reported hallucinations only in the full wakefulness. A longer duration of Parkinson's disease treatment (OR 1.35, 95% CI 1.07 to 1.72), higher Beck Depression Inventory-II scores (OR 1.07; 95% CI 1.01 to 1.14), and higher rapid eye movement sleep behavior disorder scores (OR 5.60; 95% CI 1.54 to 20.38) were independent factors associated with the presence of sleep-related hallucinations in a multivariable analysis. Sleep-related hallucinations, but not daytime hallucinations, were associated with probable rapid eye movement sleep behavior disorder. Phenomenological discrimination between sleep-related hallucinations and daytime hallucinations is important for elucidating the full pathology in Parkinson's disease and the mechanisms underlying hallucinations.

Status Cataplecticus with Rapid Eye Movement Sleep Excess in Late-onset Narcolepsy Type 1

A 57-year-old man presented with difficulty speaking and walking along with increased daytime somnolence. His symptoms fluctuated throughout the day but never completely disappeared. A neurological examination revealed mild dysarthria, limb weakness, and staggering gait. Polysomnography showed rapid eye movement (REM) sleep excess (55.0%). Multiple sleep latency tests revealed a mean sleep latency of zero minutes with sleep-onset REM periods in all naps. The Orexin-A concentration in the cerebrospinal fluid was low (50.8 pg/mL). Human leukocyte antigen testing demonstrated DQB1*0602 positivity. His neurological symptoms were relieved by clomipramine. Thus, he was diagnosed with late-onset narcolepsy type 1 with status cataplecticus.

Idiopathic rapid eye movement sleep behavior disorder in Japan: An observational study

INTRODUCTION

Idiopathic rapid eye movement sleep behavior disorder (iRBD) is one of the most specific prodromal symptoms of synucleinopathies, including Parkinson's disease (PD) and multiple system atrophy. The Japan Parkinson's Progression Markers Initiative (J-PPMI) was a prospective cohort study conducted in Japanese patients with iRBD to investigate biomarkers for prodromal synucleinopathies. We carried out an initial assessment of the J-PPMI study to reveal the factors correlated with dopamine transporter single-photon emission computed tomography (DaT) and ¹²³I-meta-iodobenzylguanidine (MIBG) myocardial scintigraphy.

METHODS

This cross-sectional study was conducted in 108 patients with iRBD, selected from the J-PPMI study. We divided the patients into four groups based on the MIBG and DaT results. We also recorded the patients' demographics and clinical data. Following PD probability calculation, we examined the biomarkers associated with DaT and MIBG.

RESULTS

Ninety-five of the enrolled patients (88%) met the diagnostic criteria for prodromal PD based on the probability score. Only five patients had normal MIBG and DaT. We identified 29 cases with decreased DaT and MIBG, all of whom met the above diagnostic criteria. Both DaT and MIBG were significantly correlated with the Japanese version of the Montreal Cognitive Assessment (MoCA-J) score.

CONCLUSION

Both DaT and MIBG are important biomarkers for confirming synucleinopathies and/or staging disease progression. Although 95% of iRBD patients were consistent with the body-first subtype concept, alpha-synuclein pathologies of iRBD might have widespread systemic involvement rather than being confined to the lower brainstem, particularly in patients with reduced MoCA-J scores.

Orexin 2 receptor-selective agonist danavorexton improves narcolepsy phenotype in a mouse model and in human patients

Narcolepsy type 1 (NT1) is a sleep disorder caused by a loss of orexinergic neurons. Narcolepsy type 2 (NT2) is heterogeneous; affected individuals typically have normal orexin levels. Following evaluation in mice, the effects of the orexin 2 receptor (OX2R)-selective agonist danavorexton were evaluated in single- and multiple-rising-dose studies in healthy adults, and in individuals with NT1 and NT2. In orexin/ataxin-3 narcolepsy mice, danavorexton reduced sleep/wakefulness fragmentation and cataplexy-like episodes during the active phase. In humans, danavorexton administered intravenously was well tolerated and was associated with marked improvements in sleep latency in both NT1 and NT2. In individuals with NT1, danavorexton dose-dependently increased sleep latency in the Maintenance of Wakefulness Test, up to the ceiling effect of 40 min, in both the single- and multiple-rising-dose studies. These findings indicate that OX2Rs remain functional despite long-term orexin loss in NT1. OX2R-selective agonists are a promising treatment for both NT1 and NT2.

Mandibular Advancement Device Therapy in Japanese Rugby Athletes with Poor Sleep Quality and Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) may contribute to poor sleep quality. This study assessed subjective sleep quality, the Respiratory Event Index (REI), reaction times, and the therapeutic effects of a custom-made mandibular advancement device (MAD) in male Japanese elite rugby athletes. The Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), and level III sleep test (REI and minimum oxygen saturation [SpO2 min]) were used to evaluate sleep quality. MAD therapy was used daily for 3 weeks. A telephone-based reaction time test of kinetic vision (the ability to identify moving objects) was recorded within 15 min of waking and over 5 days of pre- and post-MAD therapy. Differences in variables were evaluated using paired t-tests. Of the 42 players (mean age, 26.3 ± 3.7 years; mean body mass index, 28.7 ± 3.2 kg/m2) included in this study, 29 (69.0%) had poor sleep quality (PSQI > 5.5), and 27 were diagnosed with OSA (64.3%) (mild = 16/moderate = 9/severe = 2). Six were treated with MAD therapy, which significantly improved the REI (p < 0.01), SpO2 min (p < 0.001), ESS score (p < 0.001), reaction times (p < 0.01), and sleep quality. A significant reduction in reaction times suggests that OSA treatment can improve kinetic vision. Future studies should systematically evaluate the impact of sleep-disordered breathing on kinetic vision in athletes.