Electroencephalographic Finding in Idiopathic REM Sleep Behavior Disorder.

The REM sleep behavior disorder (RBD) is a type of parasomnia manifested by vivid, often frightening dreams associated with motor behaviors during REM sleep, sometimes causing injuries to patients themselves or to their bed partners. The polysomnographic features of RBD include increased muscle activity during REM sleep (REM sleep without atonia). The majority of RBD-affected persons are older men. The disorder might be idiopathic (iRBD) or secondary to neurological disorders of various kinds. iRBD management with pharmaceutical measures is usually straightforward and effective. Several longitudinal studies have revealed that a high proportion of iRBD patients convert to α-synucleinopathies such as Parkinson's disease and dementia with Lewy body disease (DLB). Considering this, many studies have been conducted to identify common clinical markers between α-synucleinopathies and iRBD or indicators for the future development of α-synucleinopathies in iRBD patients. In this context, electroencephalographic (EEG) slowing occurring while awake and asleep, which is frequently observed in DLB, has received much attention. Clarification of the association between EEG slowing and the presence of mild cognitive impairment, which is also commonly seen in early stages of DLB, has been particularly expected to offer a breakthrough for the identification of cases which might convert to α-synucleinopathies. In this article, we introduce the progress in quantitative EEG research in iRBD during the past decade. We also discuss the relationship between EEG findings and cognitive decline as well as the mechanisms of EEG changes or cognitive abnormalities in patients with the disorder. © 2015 S. Karger AG, Basel.

C9orf72 repeat expansions in rapid eye movement sleep behaviour disorder.

BACKGROUND: A large hexanucleotide repeat expansion in C9orf72 has been identified as the most common genetic cause in familial amyotrophic lateral sclerosis and frontotemporal dementia. Rapid Eye Movement Sleep Behavior Disorder (RBD) is a sleep disorder that has been strongly linked to synuclein-mediated neurodegeneration. The aim of this study was to evaluate the role of the C9orf72 expansions in the pathogenesis of RBD. METHODS: We amplified the C9orf72 repeat expansion in 344 patients with RBD by a repeat-primed polymerase chain reaction assay. RESULTS: We identified two RBD patients carrying the C9orf72 repeat expansion. Most interestingly, these patients have the same C9orf72 associated-risk haplotype identified in 9p21-linked amyotrophic lateral sclerosis and frontotemporal dementia families. CONCLUSIONS: Our study enlarges the phenotypic spectrum associated with the C9orf72 hexanucleotide repeat expansions and suggests that, although rare, this expansion may play a role in the pathogenesis of RBD.

Change in heart rate variability precedes the occurrence of periodic leg movements during sleep: an observational study.

BACKGROUND: Several reports have described that individual periodic leg movements during sleep (PLMS) activities are associated with autonomic nervous system activity occurring shortly before each PLMS activity. Nevertheless, no study has investigated dynamic changes of autonomic nervous system activity before the onset of PLMS. This study detected changes in heart rate variability (HRV) at the onset of the period with PLMS using complex demodulation method. METHODS: This study enrolled 14 patients diagnosed as having idiopathic PLMS disorder (PLMD). In periods with and without PLMS during sleep stage 2, HRV-related variables and the spectral power of fluctuation of a high frequency (HF) band (FHFB) were analyzed and compared. The changes of those parameters during transition from the period without PLMS to that with PLMS were explored. RESULTS: Spectral power in the low frequency (LF) band and very low frequency (VLF) band were higher in the period with PLMS. Additionally, the average frequency in FHFB was higher. The frequency in this band fluctuated during the period with PLMS with remarkable elevation of FHFB. Moreover, spectral powers in FHFB, LF, and VLF were remarkably elevated shortly before the beginning of the period with PLMS (FHFB, -65 s; LF, -53 s; and VLF, -45 s). CONCLUSIONS: Elevation of sympathetic nervous system activity and mean frequency fluctuation in an HF band can occur several tens of seconds before the period with PLMS. Dynamic changes in the autonomic nervous system activity might be related to the vulnerability to PLMS occurrence during the night.

[Rapid eye movement (REM) sleep behavior disorder in older adults].

Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia characterized by dream-enacting behavior associated with vivid, action-filled, or unpleasant dreams accompanied by REM sleep without atonia (RWA), a tonic or phasic electromyogram (EMG), which is an important physiological basis of RBD. Dream-enacting behaviors, such as sleep talking, shouting, and vigorous or elaborate body movements including punching, kicking, sitting up, and falling out of bed, often engender an elevated risk of self-injury and harm to others. Reportedly, this disorder often occurs in middle-aged men and a certain rate of patients with this disorder progress to alpha-synucleinopathies. Given these, correct diagnosis and proper treatment as well as clarifying its pathophysiology are desirable in our graying society.

Effectiveness of pramipexole, a dopamine agonist, on rapid eye movement sleep behavior disorder.

Rapid eye movement (REM) sleep behavior disorder (RBD) is parasomnia characterized by REM sleep without atonia (RWA) and elaborate motor activity in association with dream mentation. Periodic leg movement during sleep (PLMS) is observed in a large share of patients with RBD, suggesting a common pathology: dopaminergic dysfunction. This study was undertaken to evaluate the effectiveness and mechanism of action of pramipexole, a dopamine agonist, on RBD symptoms. Fifteen patients (57-75 years old) with RBD with a PLMS index of more than 15 events/h shown by nocturnal polysomnography were enrolled. Sleep variables, the score of severity for RBD symptoms, REM density, and PLM index were compared before and after one month or more of consecutive pramipexole treatment. Correlation analysis was conducted between the rate of change in RBD symptoms and the rate of reduction of REM density. Fourteen patients with RBD (80.0%) achieved symptomatic improvement of RBD with pramipexole treatment, which reduced REM density and PLM index during non-REM sleep despite the unchanged amount of RWA. The rate of change in RBD symptoms correlated positively with the rate of REM density reduction. Significant reduction of the PLM index was observed in non-REM sleep but not in REM sleep. Pramipexole can improve RBD symptoms, possibly because of changes in dream contents or its amount manifested as the reduction of REM density. The restricted influence of pramipexole on PLMS only during non-REM sleep suggests that other factors may affect the pathophysiology of PLMS during the REM sleep period in RBD.

Changes in respiratory disorder parameters during the night in patients with obstructive sleep apnoea.

BACKGROUND AND OBJECTIVE: Patients with OSA frequently experience cardiovascular events, especially late at night. This phenomenon raises the possibility that respiratory disorders are progressively aggravated during the course of nocturnal sleep. To test this hypothesis, we investigated the changes in respiratory disorder parameters occurring during the night in patients with OSA, in the supine position and in all sleep positions. METHODS: Thirty consecutive patients with OSA were enrolled in the study and categorized into those with moderate OSA (n = 12; AHI <40 events/h) and those with severe OSA (n=18; AHI ≥40 events/h). To identify the time during the sleep period at which changes in respiratory disorder parameters were most pronounced, AHI, mean duration of apnoea and average SaO(2) were assessed during the early, middle and late segments of sleep, in the supine position and in all sleep positions. RESULTS: AHI decreased significantly with time during the course of the total sleep period, and especially during non-rapid eye movement (NREM) sleep. In the group with severe OSA, prolongation of the mean duration of apnoea and the decrease in average SaO2 were also significant in the late segment of sleep in the supine position, especially during NREM sleep. CONCLUSIONS: In patients with severe OSA, there was progressive prolongation of the mean duration of apnoea late at night and this was associated with aggravation of hypoxia in the supine position during NREM sleep. This phenomenon may contribute to the remarkable rise in blood pressure early in the morning, possibly increasing the vulnerability of these patients to cardiovascular events.

Correlations among insomnia symptoms, sleep medication use and depressive symptoms.

AIM: To elucidate the factors associated with insomnia symptoms and the use of sleep medication, and the correlations among insomnia symptoms, sleep medication use and depressive symptoms in the general population. METHODS: This survey was conducted in a rural community of Japan. Questionnaires consisted of basic information, the Pittsburgh Sleep Quality Index, and a 12-item version of the Center for Epidemiological Studies Depression scale, and were administered to all community members aged 20 years or over. A total of 2822 respondents with valid answers were subjected to analysis. RESULTS: Occurrence of insomnia symptoms appeared to be associated with advancing age and existence of depressive symptoms. The extent of sleep medication use in the entire sample was 9%, and the value in the subjects with insomnia symptoms was 26%. Sleep medication use in insomniacs was associated with female sex and advancing age as well as higher scores in subcomponents of both poor subjective sleep quality and prolonged delay of sleep onset. Depressive symptoms were worst in the group with insomnia symptoms using sleep medication, and were significantly lower in the group without insomnia symptoms using sleep medication. CONCLUSIONS: Our study revealed that female sex, advancing age, depressive symptoms, poor sleep quality, and prolonged delay of sleep onset appeared as risk factors for sleep medication use. Insomnia symptoms were suspected to act as an exacerbating factor for depressive symptoms. However, our findings suggested that appropriate use of sleep medication could reduce depressive symptoms in the subjects with insomnia symptoms.

Comparison of the clinical features of rapid eye movement sleep behavior disorder in patients with Parkinson's disease and multiple system atrophy.

AIMS: The aim of this study was to evaluate differences in the clinical presentation and polysomnographic characteristics of rapid eye movement sleep behavior disorder (RBD) between patients with Parkinson's disease (PD) and those with multiple system atrophy (MSA). METHODS: We conducted clinical interviews examining RBD symptoms, including violent and non-violent behaviors, in 49 patients with PD and 16 patients with MSA (as well as their bed partners) and performed polysomnography on all subject patients. RESULTS: Twenty-seven patients with PD (55.1%) and 11 patients with MSA (68.8%) had rapid eye movement sleep without atonia (RWA) on polysomnogram. The relative amounts of RWA were quite similar between the two groups. For most of the RWA-positive patients in both groups, RBD symptoms remained non-violent or silent. RBD symptoms in PD patients seemed to increase with the course of PD, while most of the RBD symptoms in the MSA patients occurred just prior to or at the onset of MSA and then disappeared within a short period. CONCLUSION: Although PD and MSA frequently accompany RWA, RBD symptoms often remain non-violent or silent. Differences in the course of RBD symptoms in patients with PD and MSA may reflect the difference in the degeneration process of the two disorders.

Principal Component Analysis of Multimodal Neuromelanin MRI and Dopamine Transporter PET Data Provides a Specific Metric for the Nigral Dopaminergic Neuronal Density.

The loss of dopaminergic (DA) neurons in the substantia nigra (SN) is a major pathophysiological feature of patients with Parkinson's disease (PD). As nigral DA neurons contain both neuromelanin (NM) and dopamine transporter (DAT), decreased intensities in both NM-sensitive MRI and DAT PET reflect decreased DA neuronal density. This study demonstrates that a more specific metric for the nigral DA neuronal density can be derived with multimodal MRI and PET. Participants were 11 clinically diagnosed PD patients and 10 age and gender matched healthy controls (HCs). Two quantities, the NM-related index (RNM) and the binding potential of the radiotracer [18F]FE-PE2I to DAT (BPND) in SN, were measured for each subject using MRI and PET, respectively. Principal component analysis (PCA) was applied to the multimodal data set to estimate principal components. One of the components, PCP, corresponds to a basis vector oriented in a direction where both BPND and RNM increase. The ability of BPND, RNM and PCP to discriminate between HC and PD groups was compared. Correlation analyses between the motor score of the unified Parkinson's disease rating scale and each metric were also performed. PCP, BPND and RNM for PD patients were significantly lower than those for HCs (F = 16.26, P<0.001; F = 6.05, P = 0.008; F = 7.31, P = 0.034, respectively). The differential diagnostic performance between the HC and PD groups as assessed by the area under the receiver-operating characteristic curve was best for PCP (0.94, 95% CI: 0.66-1.00). A significant negative correlation was found between the motor severity score and PCp (R = -0.70, P<0.001) and RNM (R = -0.52, P = 0.015), but not for BPND (R = -0.36, P = 0.110). PCA of multimodal NM-sensitive MRI and DAT PET data provides a metric for nigral DA neuronal density that will help illuminate the pathophysiology of PD in SN. Further studies are required to explore whether PCA is useful for other parkinsonian syndromes.

Longitudinal study of regional cerebral blood flow in elderly patients with idiopathic rapid eye movement sleep behavior disorder.

AIM: Single photon emission computed tomography (SPECT) studies showed that regional cerebral blood flow (rCBF) abnormalities in idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD) are similar to those seen in Parkinson's disease (PD) and dementia with Lewy bodies (DLB). The aim of the present study was to assess the longitudinal rCBF changes in patients with iRBD using repeated SPECT. METHODS: Nine patients with iRBD (7 men and 2 women; mean age 71.1 ± 3.2 years) underwent baseline and follow-up SPECT studies (a mean interval of 22.8 ± 9.2 months). RESULTS: A decrease in rCBF was found in bilateral parietotemporal and occipital areas at the first and second SPECT. Compared with the first SPECT, the second SPECT showed a decreased rCBF in the medial portions of the parietooccipital lobe with a significant decrease in rCBF of the right posterior cingulate. None of the patients showed any neurological deficits, including extrapyramidal and cerebellar signs, visual hallucinations, and neuropsychological impairments during the study. CONCLUSION: These findings suggest that longitudinal measurements of rCBF can show the presence of progressing neurodegenerative process in iRBD. Longitudinal SPECT study can be used to monitor the progression of degenerative process in patients with iRBD, even though there were no evolving neurological and neuropsychiatric impairments.

Impact of frequency of nightmares comorbid with insomnia on depression in Japanese rural community residents: a cross-sectional study.

OBJECTIVE: Nightmares and insomnia are known to be associated with the development and aggravation of depression. Our community-based study was conducted to clarify the relation between the impacts of nightmares and insomnia on depression. METHODS: A cross-sectional questionnaire-based survey was administered to residents of a rural community in Japan. In all, 2822 participants responded to questions assessing personal characteristics, the Pittsburgh Sleep Quality Index (PSQI) for assessing insomnia, and a 12-item version of the Center for Epidemiological Studies Depression scale (CES-D) for evaluating depression. Nightmare frequency was assessed using an item for nightmares on the PSQI. RESULTS: Nightmares more frequently occurred in participants with insomnia than those without (P < .01). Multiple regression analysis revealed that the scores of both nightmares and insomnia were significantly associated with the increase in depression score (nightmares (ß = 0.09, P < .01); insomnia (ß = 0.39, P < .01)). Participants with coexisting nightmares and insomnia showed higher depression scores than participants with insomnia alone or those with nightmares who did not have insomnia (P < .01). CONCLUSIONS: Insomnia and nightmares independently and additively impact the aggravation of depression.

Validation of the Japanese version of the Ford Insomnia Response to Stress Test and the association of sleep reactivity with trait anxiety and insomnia.

OBJECTIVE: Our study was conducted to validate the Japanese version of the Ford Insomnia Response to Stress Test (FIRST-J) and to clarify the association of the measure with trait anxiety and insomnia in healthy subjects and insomnia patients. METHODS: We studied 161 healthy subjects and 177 insomnia patients who completed the FIRST-J, Pittsburgh Sleep Quality Index (PSQI), Athens Insomnia Scale (AIS), and State-Trait Anxiety Inventory-Trait (STAI). The healthy subjects and the insomnia patients were classified, respectively, into two groups with high FIRST-J and low FIRST-J scores (divided by the median value of healthy subjects). RESULTS: Cronbach α coefficients of the FIRST-J in the insomnia patients and healthy subjects were 0.89 and 0.87, respectively. Factor analysis revealed that the FIRST-J had a single-factor structure. The FIRST-J score significantly correlated with all other measures in the healthy subjects, though the score only correlated with the score of the STAI in the insomnia patients. The healthy subjects with high FIRST-J scores showed higher scores of the AIS and STAI than those with low FIRST-J scores. Furthermore, insomnia patients had a higher total score of the FIRST-J than the healthy subjects. CONCLUSIONS: The FIRST-J is an important tool for assessing vulnerability to insomnia.

Electroencephalographic findings related with mild cognitive impairment in idiopathic rapid eye movement sleep behavior disorder.

STUDY OBJECTIVES: Mild cognitive impairment (MCI) and electroencephalographic (EEG) slowing have been reported as common findings of idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD) and α-synucleinopathies. The objective of this study is to clarify the relation between MCI and physiological markers in iRBD. DESIGN: Cross-sectional study. SETTING: Yoyogi Sleep Disorder Center. PATIENTS OR PARTICIPANTS: Thirty-one patients with iRBD including 17 younger patients with iRBD (younger than 70 y) and 17 control patients for the younger patients with iRBD. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Montreal Cognitive Assessment (MoCA) and n-polysomnogram (PSG) were conducted of all participants. In patients with iRBD, the factors associated with MCI were explored among parameters of REM sleep without atonia (RWA), score of Sniffin' Sticks Test (threshold-discrimination-identification [TDI] score), RBD morbidity, and RBD severity evaluated with the Japanese version of the RBD questionnaire (RBDQ-JP). The younger iRBD group showed significantly lower alpha power during wake and lower MoCA score than the age-matched control group. MCI was detected in 13 of 17 patients (76.5%) on MoCA in this group. Among patients wtih iRBD, the MoCA score negatively correlated with age, proportion of slow wave sleep, TDI score, and EEG spectral power. Multiple regression analysis provided the following equation: MoCA score = 50.871-0.116*age -5.307*log (δ power during REM sleep) + 0.086*TDI score (R² = 0.598, P < 0.01). The standardized partial regression coefficients were -0.558 for age, -0.491 for log (δ power during REM sleep), and 0.357 for TDI score (F = 9.900, P < 0.001). CONCLUSIONS: Electroencephalographic slowing, especially during rapid eye movement sleep and olfactory dysfunction, was revealed to be associated with cognitive decline in idiopathic rapid eye movement sleep behavior disorder.

Factors associated with the effect of pramipexole on symptoms of idiopathic REM sleep behavior disorder.

BACKGROUND: The clinical effectiveness of pramipexole (PPX), a candidate treatment for idiopathic rapid eye movement sleep behavior disorder (iRBD), varies among individuals. This study investigates factors associated with PPX effectiveness for treating RBD symptoms. METHODS: Ninety-eight consecutive patients with RBD who had taken PPX or clonazepam (CNZP) for more than three months were enrolled. Factors associated with PPX effectiveness were examined: the ratio of REM sleep without atonia to total REM sleep (RWA/REM), length of RBD morbidity, frequency of vocalization or abnormal behavior, and Sniffin' Stick Test scores. These factors were also compared among the responders to PPX monotherapy, CNZP monotherapy, and PPX + CNZP combined therapy. RESULTS: PPX was efficacious in 61.7% (50/81) of the subject patients. RWA/REM was associated with PPX effectiveness. The cut-off rate of RWA/REM for predicting PPX effectiveness was estimated as 16.8%. Responders to PPX + CNZP combined therapy showed significantly higher RWA/REM and frequency of vocalization or dream enactment behavior than either responders to monotherapy with PPX or to CNZP. CONCLUSION: PPX is probably applicable as an alternative to CNZP, especially for mild iRBD cases with a lower rate of RWA. Results of this study suggest that dopaminergic dysfunction can play a role in iRBD pathophysiology.

Do patients with rapid eye movement sleep behavior disorder have a disease-specific personality?

OBJECTIVES: Rapid eye movement sleep behavior disorder (RBD) occurs idiopathically (iRBD), frequently representing a prodromal phase of Parkinson's disease (PD). Previous reports have described that patients with PD have premorbid personality profiles such as industriousness, inflexibility, cautiousness, and lack of novelty seeking. As well, psychological stress often aggravates RBD symptoms. These phenomena encouraged us to investigate personality profiles in iRBD patients. METHODS: In this study, 53 patients with iRBD and 49 age and sex-matched healthy controls (HC) were enrolled. We used the revised version of the NEO Personality Inventory (NEO-PIR) to measure the personality of these subjects, and the 5 domains and the 30 facets of the NEO-PIR were compared between the two groups. Within the iRBD group, we investigated the association between RBD variables, e.g. the proportion of REM sleep without atonia (RWA/REM), length of RBD morbidity, frequency of vocalization or abnormal behavior, and the variables of NEO-PIR. RESULTS: In the patients, olfactory function was significantly lower than that of healthy controls, but the inventory differences were not significant. The inventory showed no association with any RBD variable, or the existence of aggravation of these symptoms triggered by psychological stress, or olfactory dysfunction. CONCLUSION: These results suggest that RBD patients do not have a personality profile that might predict PD development. The personality profile itself cannot explain the psychological-stress-dependent aggravation of RBD symptoms.

Validation of the Japanese version of the REM sleep behavior disorder questionnaire (RBDQ-JP).

BACKGROUND: The rapid eye movement (REM) sleep behavior disorder (RBD) questionnaire (RBDQ)-Hong Kong was the first tool developed for quantifying the severity of RBD. This study was conducted to validate the Japanese version of the questionnaire and to investigate its reliability, validity, and responsiveness. METHODS: Patients with idiopathic RBD and sex and age-matched healthy controls completed the Japanese version of the questionnaire (RBDQ-JP). In addition to the evaluation of its reliability and validity, the questionnaire scores were compared between those earned before and those earned after pharmaceutical treatment to assess the questionnaire's responsiveness. RESULTS: The questionnaire demonstrated high test-retest reliability and moderate internal consistency. The best cut-off score was 19/20 with a sensitivity of 97.2% and a specificity of 97.5%. Exploratory factor analysis revealed that the questionnaire consists of the following two factors: Factor 1, Dream and dream-related behaviors and Factor 2, Violent/complex behaviors. Among the patients, significant correlation was found between the rate of change of questionnaire score and the clinical global impression improvement score with pharmaceutical treatment (rs=-0.829, p<0.01). CONCLUSIONS: The RBDQ-JP provides satisfactory reliability, validity, and responsiveness. The questionnaire is suitable for severity assessment and for assessing the RBD treatment outcome.

Impaired decision-making in idiopathic REM sleep behavior disorder.

BACKGROUND: Patients with REM sleep behavior disorder (RBD) frequently develop Parkinson's disease (PD), which can impair decision-making ability. This study was undertaken to investigate decision-making ability and its relation to olfactory function in patients with idiopathic RBD. METHODS: This study used the Iowa Gambling Task (IGT) and the Sniffin' Stick Test for examination of 38 patients with idiopathic RBD (iRBD) and 34 age-matched healthy control subjects (HC). Associations between these test results and other clinical RBD variables were also assessed. RESULTS: Total IGT score and Sniffin' Stick Test scores were significantly lower in the iRBD group than in the HC group. The iRBD group IGT scores in the first, third, and final blocks were significantly lower than those of the HC group. In the iRBD group, no association was found between the total IGT score and the Sniffin' Stick Test score or any clinical RBD variable. CONCLUSIONS: Impaired decision-making associated with iRBD can herald PD. However, decision-making disability is thought to appear irrespective of olfactory dysfunction and progression of RBD pathology.

A two-year follow-up study on the symptoms of sleep disturbances/insomnia and their effects on daytime functioning.

OBJECTIVE: This study attempts to identify changes in the symptoms of sleep disturbances/insomnia over a two-year course and their effects on daytime functioning. METHODS: We administered two population-based epidemiological surveys in 2005 and 2007 to participants from rural Japan. RESULTS: In the first survey, 30.7% of the subjects reported sleep disturbances/insomnia. Among them, 60.9% reported sleep problems at the two-year follow-up. A comparison of sleep disturbances/insomnia, and subjective daytime functioning measures between the new incident cases and persistent poor sleepers revealed that the total score of persistent poor sleepers was significantly lower than that of new incident cases on the Pittsburgh Sleep Quality Index and physical quality of life (QoL) but not mental QoL. Longitudinal comparisons of the symptoms of sleep disturbances/insomnia in persistent poor sleepers revealed that sleep efficiency was significantly worse at follow-up. Exacerbation of the symptoms of sleep disturbances/insomnia at follow-up was observed in mild but not severe cases. CONCLUSIONS: Sleep efficiency progressively worsens over time, and physical QoL can deteriorate as sleep disturbances/insomnia become chronic. Since the symptoms of sleep disturbances/insomnia and their daytime effects are exacerbated even in mild cases, early intervention and treatment are necessary.

Differences in findings of nocturnal polysomnography and multiple sleep latency test between narcolepsy and idiopathic hypersomnia.

OBJECTIVES: To compare differences in nocturnal and daytime polysomnographic findings between narcolepsy (NA) with and without cataplexy (CA) and idiopathic hypersomnia without long sleep time (IHS w/o LST). METHODS: Nocturnal polysomnography (n-PSG) and multiple sleep latency test (MSLT) findings were compared among subjects with NA with CA (n=52), NA without CA (n=62), and IHS w/o LST (n=50). RESULTS: The NA with CA group had significantly more disrupted and shallower nocturnal sleep than the other groups. On MSLT, the IHS w/o LST group had significantly longer sleep latency (SL) compared with the two NA groups. The latter two groups did not show statistical differences in diurnal variation of SL. CONCLUSIONS: The IHS w/o LST group had milder objective daytime sleepiness compared with the NA groups. In patients with NA, nocturnal sleep disturbances appeared only in cases with CA, despite a similar trend in diurnal changes in sleep propensity between the two NA groups. SIGNIFICANCE: Objective nocturnal sleep disturbances are specific to NA patients with CA, whereas diurnal variations of sleep propensity are observed irrespective of the presence of CA among NA patients. These findings could be helpful for choosing optimal treatment plans for patients with these disorders.