A normative study of the maintenance of wakefulness test (MWT)

Cuadro clínico del síndrome de apnea-hipopnea obstructiva del sueño (SAHOS)

El pilar para el diagnóstico del síndrome de apnea-hipopnea obstructiva del sueño (SAHOS) es el cuadro clínico obtenido mediante una historia clínica detallada. Los síntomas son referidos por el paciente o su compañero de cama y se pueden dar durante el sueño o la vigilia; estos últimos se presentan como consecuencia del trastorno del sueño. Los síntomas son consecuencia de la obstrucción de la vía aérea superior, de la hipoxia intermitente o de la fragmentación repetida del sueño.Para el diagnóstico de SAHOS, se deben tener en cuenta los factores agravantes, las comorbilidades, los antecedentes familiares, el examen físico, la obtención de medidas antropométricas, los signos vitales y los hallazgos anatómicos estructurales asociados con este síndrome o con alteraciones congénitas que lo predispongan. Tener conocimiento de estos aspectos clínicos es fundamental para alcanzar una buena aproximación a su diagnóstico.

Subjective and Objective Assessment of Hypersomnolence

This article describes clinical approaches to assessing sleepiness. Subjective sleep scales are used in clinical settings but have significant limitations. Likewise, objective tools may have prohibitive expense, and practical administration considerations may prohibit regular use. Gold standard tests include the multiple sleep latency test and maintenance of wakefulness test. These studies are criticized for a variety of reasons but are useful in appropriate clinical context. New tools suggest novel ways to assess sleepiness and will likely be more prominent in clinical assessments over time. This article outlines subjective scales and objective tools and suggests situations where particular instruments may be appropriate.

Hypersomnolence, Hypersomnia, and Mood Disorders

Relationships between symptoms of hypersomnolence, psychiatric disorders, and hypersomnia disorders (i.e., narcolepsy and idiopathic hypersomnia) are complex and multidirectional. Hypersomnolence is a common complaint across mood disorders; however, patients suffering from mood disorders and hypersomnolence rarely have objective daytime sleepiness, as assessed by the current gold standard test, the Multiple Sleep Latency Test. An iatrogenic origin of symptoms of hypersomnolence, and sleep apnea syndrome must be considered in a population of psychiatric patients, often overweight and treated with sedative drugs. On the other hand, psychiatric comorbidities, especially depression symptoms, are often reported in patients with hypersomnia disorders, and an endogenous origin cannot be ruled out. A great challenge for sleep specialists and psychiatrists is to differentiate psychiatric hypersomnolence and a central hypersomnia disorder with comorbid psychiatric symptoms. The current diagnostic tools seem to be limited in that condition, and further research in that field is warranted.

Efficacy, Safety, and Tolerability of Armodafinil Therapy for Hypersomnia Associated with Dementia with Lewy Bodies: A Pilot Study

BACKGROUND/AIMS

Hypersomnia is common in dementia with Lewy bodies (DLB). We assessed the efficacy, safety, and tolerability of armodafinil for hypersomnia associated with DLB.

METHODS

We performed a 12-week pilot trial of armodafinil therapy (125-250 mg orally daily) in DLB outpatients with hypersomnia. The patients underwent neurologic examinations, a neuropsychological battery, laboratory testing, electrocardiography, and polysomnography. Efficacy was assessed at 2, 4, 8, and 12 weeks. Safety assessment included laboratory examinations, QTc interval, and heart rate. Tolerability was assessed by analysis of adverse events. Data were analyzed using the last-observation-carried-forward method.

RESULTS

Of 20 participants, 17 completed the protocol. The median age was 72 years, most of the participants were men (80%), and most had spouses as caregivers. The Epworth Sleepiness Scale (p < 0.001), Maintenance of Wakefulness Test (p = 0.003), and Clinical Global Impression of Change (p < 0.001) scores improved at week 12. The Neuropsychiatric Inventory total score (p = 0.003), visual hallucinations (p = 0.003), and agitation (p = 0.02) improved at week 4. Caregiver overall quality of life improved at week 12 (p = 0.004). No adverse events occurred.

CONCLUSION

These pilot data suggest improvements in hypersomnia and wakefulness and reasonable safety and tolerability of armodafinil therapy in hypersomnolent patients with DLB. Our findings inform the use of pharmacologic strategies for managing hypersomnolence in these patients.

Findings of the Maintenance of Wakefulness Test and its relationship with response to modafinil therapy for residual excessive daytime sleepiness in obstructive sleep apnea patients adequately treated with nasal continuous positive airway pressure

OBJECTIVE

We aimed to examine the relationship between subjective and objective sleepiness in obstructive sleep apnea syndrome (OSAS) patients with residual sleepiness, and to determine whether baseline objective sleepiness severity predicts the response to modafinil therapy.

METHODS

Data were obtained from a randomized, placebo-controlled modafinil (200 mg/day) study in Japanese OSAS patients with residual sleepiness receiving nasal continuous positive pressure (n-CPAP) treatment. We analyzed 50 participants whose subjective (Epworth Sleepiness Scale [ESS] total score) and objective (Maintenance of Wakefulness Test [MWT] sleep latency) sleepiness were evaluated before and after treatment. Subjects were dichotomized into two subgroups according to the mean baseline MWT sleep latency. ESS total score and MWT sleep latency changes after treatment were compared between the placebo and modafinil groups in both subgroups.

RESULTS

The mean baseline ESS total score and MWT sleep latency were 14.1 ± 2.8 and 14.2 ± 4.9 min, respectively; there was no significant correlation between these two variables. Patient characteristics were similar between the two subgroups (MWT sleep latency: <14 min, n = 23; ≥14 min, n = 27). In the <14-min subgroup, changes in ESS total score and MWT sleep latency after treatment were significantly greater in the modafinil group than in the placebo group (p = 0.005). In the ≥14-min subgroup, changes in these parameters did not differ between the treatment groups.

CONCLUSION

In OSAS patients with residual sleepiness, the objective sleepiness level was not as high as expected, despite increased subjective sleepiness. Improvements in subjective and objective sleepiness seemed difficult to achieve with modafinil treatment among subjects with less objective sleepiness.

French consensus. Hypersomnolence: Evaluation and diagnosis

Sleepiness is one of the most frequently reported complaints in adults and children during specialised sleep consultations. It is responsible for an alteration that can be severe in quality of life, a lowering of academic or professional performance, and domestic or work accidents. Hypersomnolence is the first cause of road accidents on the highway, responsible for a third of fatal accidents. Furthermore its presence is associated with an increased risk of morbi-mortality related to cardiovascular and neurodegenerative pathologies. Hence, its represents a real public health issue. Recent revisions in international classifications have clarified confusing terminology, and the complaint of hypersomnia has now been replaced by the terms hypersomnolence or excessive sleepiness. It is clinically defined as an excessive quantity of sleep over 24hours, and/or by an alteration in the quality of arousal defined as incapacity to maintain a satisfactory level of vigilance during the day or in the morning on awakening (defined as sleep inertia). The evaluation of sleepiness requires a rigorous clinical approach, completed by subjective and objective measurements. The Epworth Sleep Scale, Multiple Sleep Latency Tests and the Maintenance of Wakefulness Test are the most studied and used in clinical practice. However, to date, no gold standard measurement of excessive sleepiness exists, and there are no quantifiable biological markers. It is therefore important to optimise our evaluation tools, improve our pathophysiological understanding of sleepiness, and define genetic and environmental risk factors.

Intermittent hypoxemia and sleep fragmentation: associations with daytime alertness in obese sleep apnea patients living at moderate altitude

BACKGROUND

Although obstructive sleep apnea (OSA) has long been associated with daytime sleepiness, far less is known about its association with the ability to remain awake. The aim of this study was to examine the relative importance of inter-correlated measures of OSA severity (eg, various indices of oxygen saturation and sleep fragmentation) in the ability to stay alert as measured objectively by the Maintenance of Wakefulness Test (MWT), defined by a mean sleep latency of ≥12 min.

METHODS

Seventy-eight obese women and men of similar age and body mass index living at altitude (Mexico City) underwent standard polysomnography, MWT, and completed validated sleep-related questionnaires.

RESULTS

Men had more severe sleep apnea than women (p = 0.002) and were also less alert on MWT (p = 0.022). Logistic regression models indicated that measures of desaturation consistently predicted MWT-defined alertness, whereas varied measures of sleep fragmentation did not. Nearly a third of the variance (r(2) = 0.304) in MWT-defined alertness was accounted for by the number of desaturations per hour of sleep (p = 0.003), which is considerably higher than other studies have reported in different populations.

CONCLUSION

The ability to remain awake in obese patients is best accounted for by hypoxemia rather than sleep fragmentation. Whether the size of this effect reflects differences in the population under study (eg, extent of obesity, racial background, residence at moderate altitude) and/or is a function of the measurement of alertness with the MWT remains uncertain.

Occupational Sleep Medicine

Sleep and circadian rhythms significantly impact almost all aspects of human behavior and are therefore relevant to occupational sleep medicine, which is focused predominantly around workplace productivity, safety, and health. In this article, 5 main factors that influence occupational functioning are reviewed: (1) sleep deprivation, (2) disordered sleep, (3) circadian rhythms, (4) common medical illnesses that affect sleep and sleepiness, and (5) medications that affect sleep and sleepiness. Consequences of disturbed sleep and sleepiness are also reviewed, including cognitive, emotional, and psychomotor functioning and drowsy driving.

Maintenance of Wakefulness and Occupational Injuries among Workers of an Italian Teaching Hospital

BACKGROUND

To assess in a laboratory setting the ability to stay awake in a sample of workers of an Italian hospital and to investigate the association between that ability and the risk of occupational injury.

METHODS

Nine workers at the University Hospital of Udine who reported an occupational injury in the study period (cases), and seven noninjured workers (controls) underwent a polysomnography and four 40-minute maintenance of wakefulness tests (MWT). Differences in sleep characteristics and in wakefulness maintenance were assessed using Wilcoxon's rank sums tests and Fisher's exact tests.

RESULTS

Controls had greater sleep latency, lower total sleep time, fewer leg movements, and a higher percentage ratio of cycling alternating pattern, were more likely not to fall asleep during the MWT and were less likely to have two or more sleep onsets. Although not all the differences reached statistical significance, cases had lower sleep onset times in Trials 1-3.

CONCLUSION

In the literature, the evidence of an association between MWT results and real life risk of accidents is weak. Our results suggest a relationship between the MWT results and the risk of injury among hospital workers.

Regularity of cardiac rhythm as a marker of sleepiness in sleep disordered breathing

Aim

The present study aimed to analyse the autonomic nervous system activity using heart rate variability (HRV) to detect sleep disordered breathing (SDB) patients with and without excessive daytime sleepiness (EDS) before sleep onset.

Methods

Two groups of 20 patients with different levels of daytime sleepiness -sleepy group, SG; alert group, AG- were selected consecutively from a Maintenance of Wakefulness Test (MWT) and Multiple Sleep Latency Test (MSLT) research protocol. The first waking 3-min window of RR signal at the beginning of each nap test was considered for the analysis. HRV was measured with traditional linear measures and with time-frequency representations. Non-linear measures -correntropy, CORR; auto-mutual-information function, AMIF- were used to describe the regularity of the RR rhythm. Statistical analysis was performed with non-parametric tests.

Results

Non-linear dynamic of the RR rhythm was more regular in the SG than in the AG during the first wakefulness period of MSLT, but not during MWT. AMIF (in high-frequency and in Total band) and CORR (in Total band) yielded sensitivity > 70%, specificity >75% and an area under ROC curve > 0.80 in classifying SG and AG patients.

Conclusion

The regularity of the RR rhythm measured at the beginning of the MSLT could be used to detect SDB patients with and without EDS before the appearance of sleep onset.

Mutual information measures applied to EEG signals for sleepiness characterization

Excessive daytime sleepiness (EDS) is one of the main symptoms of several sleep related disorders with a great impact on the patient lives. While many studies have been carried out in order to assess daytime sleepiness, the automatic EDS detection still remains an open problem. In this work, a novel approach to this issue based on non-linear dynamical analysis of EEG signal was proposed. Multichannel EEG signals were recorded during five maintenance of wakefulness (MWT) and multiple sleep latency (MSLT) tests alternated throughout the day from patients suffering from sleep disordered breathing. A group of 20 patients with excessive daytime sleepiness (EDS) was compared with a group of 20 patients without daytime sleepiness (WDS), by analyzing 60-s EEG windows in waking state. Measures obtained from cross-mutual information function (CMIF) and auto-mutual-information function (AMIF) were calculated in the EEG. These functions permitted a quantification of the complexity properties of the EEG signal and the non-linear couplings between different zones of the scalp. Statistical differences between EDS and WDS groups were found in β band during MSLT events (p-value < 0.0001). WDS group presented more complexity than EDS in the occipital zone, while a stronger nonlinear coupling between occipital and frontal zones was detected in EDS patients than in WDS. The AMIF and CMIF measures yielded sensitivity and specificity above 80% and AUC of ROC above 0.85 in classifying EDS and WDS patients.

A generalized estimating equation approach to analysis of maintenance of wakefulness testing in a study of lisdexamfetamine dimesylate, armodafinil, and placebo in sleep-deprived adults

In a study of acute sleep deprivation in healthy male volunteers randomized to double-blind treatment with lisdexamfetamine dimesylate (20, 50, or 70 mg), placebo control, or an active control (armodafinil 250 mg), Maintenance of Wakefulness Test data were compared using a generalized estimating equation analysis to eliminate the need for unequivocal sleep latency imputation. Compared with placebo across all Maintenance of Wakefulness Tests, all active treatments were associated with lower risk of falling asleep (risk ratio [95% confidence interval]): 0.45 (0.27-0.76; P = 0.0026), 0.10 (0.05-0.20; P < 0.0001), and 0.05 (0.02-0.14; P < 0.0001) for 20, 50, and 70 mg lisdexamfetamine dimesylate, respectively, and 0.11 (0.06-0.21; P < 0.0001) for the active control. Sleep-risk ratios were similar for lisdexamfetamine dimesylate 50 or 70 mg and for the active control, but lisdexamfetamine 20 mg was associated with a greater risk of falling asleep compared with the active control (4.13 [1.97-8.67]; P = 0.0002). Generalized estimating equation analysis detected wake-promoting effects of active treatments and eliminating data imputation, suggesting model utility in future studies.

The effect of intranasal orexin-A (hypocretin-1) on sleep, wakefulness and attention in narcolepsy with cataplexy

Narcolepsy with cataplexy is a sleep dysregulation disorder with alterations of REM sleep, i.e., sleep onset REM periods and REM sleep instability. Deficient orexin-A (hypocretin-1) signaling is assumed to be a major cause of narcolepsy with cataplexy. In this study we investigated fourteen subjects with narcolepsy with cataplexy in a within-subject, random-order crossover, placebo-controlled design. Patients received double-blinded intranasal orexin-A (435 nmol) or sterile water (placebo) in the morning. Administration was preceded by an adaptation night and followed by a modified maintenance of wakefulness test, attention testing and a second full night of polysomnographic recording. We found comparable sleep behavior during the adaptation nights between both conditions. After orexin-A administration patients had less wake-REM sleep transitions and a decreased REM sleep duration. In the subsequent night, patients showed an increased N2 duration. In the test of divided attention, patients had fewer false reactions after orexin-A administration. Our results support orexin-A to be a REM sleep stabilizing factor and provide functional signs for effects of orexin-A on sleep alterations and attention in narcolepsy with cataplexy.

Fluctuations in cognition and alertness vary independently in dementia with Lewy bodies

Fluctuations in mental status are 1 of the core diagnostic criteria for dementia with Lewy bodies (DLB) and are thought to reflect variability in daytime alertness. Previous attempts to study fluctuations have been limited to caregiver reports, observer rating scales, short segments of electroencephalography, or motor-dependent, reaction time tests. Concordance among such measures is often poor, and fluctuations remain difficult to quantify. We compared fluctuations in cognition and alertness in patients with DLB (n = 13) and idiopathic Parkinson's disease (PD) (n = 64), a condition associated with deficits in daytime alertness. We systematically and repeatedly collected cognitive and physiologic measures during a 48-hour inpatient protocol in a sound-attenuated sleep laboratory in a geriatric hospital. Cognitive fluctuations were analyzed using coefficients of variation (COVs) derived from performance on a bedside examination familiar to clinicians (digit span). Alertness fluctuations were assessed objectively using COVs from the polysomnographically-based Maintenance of Wakefulness Test. Despite predictably lower mean digit span performances, DLB patients demonstrated significantly greater cognitive fluctuations than PD patients (P < 0.001), even when groups were matched on general cognitive impairment. There were no group differences in alertness fluctuations, although DLB patients were less alert than PD patients not receiving dopaminergics. The prevailing assumption that fluctuations in cognition in DLB are reflected in fluctuations in daytime alertness was not supported by objective, physiological measurements. Fluctuating mental status in DLB patients can be detected with repeated administration of a simple bedside exam that can be adapted to a clinic setting.

Evaluating the impact of treatment for sleep/wake disorders on recovery of cognition and communication in adults with chronic TBI

OBJECTIVE

To longitudinally examine objective and self-reported outcomes for recovery of cognition, communication, mood and participation in adults with traumatic brain injury (TBI) and co-morbid post-traumatic sleep/wake disorders.

DESIGN

Prospective, longitudinal, single blind outcome study.

SETTING

Community-based.

PARTICIPANTS

Ten adults with moderate-severe TBI and two adults with mild TBI and persistent symptoms aged 18-58 years. Six males and six females, who were 1-22 years post-injury and presented with self-reported sleep/wake disturbances with onset post-injury.

INTERVENTIONS

Individualized treatments for sleep/wake disorders that included sleep hygiene recommendations, pharmacological interventions and/or treatments for sleep apnea with follow-up.

MAIN OUTCOME MEASURES

Insomnia Severity Index, Beck Depression and Anxiety Inventories, Latrobe Communication Questionnaire, Speed and Capacity of Language Processing, Test of Everyday Attention, Repeatable Battery for the Assessment of Neuropsychological Status, Daily Cognitive-Communication and Sleep Profile.

RESULTS

Group analysis revealed positive trends in change for each measure and across sub-tests of all measures. Statistically significant changes were noted in insomnia severity, p = 0.0003; depression severity, p = 0.03; language, p = 0.01; speed of language processing, p = 0.007.

CONCLUSIONS

These results add to a small but growing body of evidence that sleep/wake disorders associated with TBI exacerbate trauma-related cognitive, communication and mood impairments. Treatment for sleep/wake disorders may optimize recovery and outcomes.

The maintenance of wakefulness test in pediatric narcolepsy

Objective tools are needed to assess the response to treatment in pediatric narcolepsy. This article presents a single-center experience documenting the use of the maintenance of wakefulness test (MWT) in a pediatric series. This study reviewed the charts of children with narcolepsy who had an MWT performed between January 2008 and June 2012. A cutoff was used for mean sleep latency: <8 minutes for inadequate control of hypersomnia, and >20 minutes to indicate adequate control on medications. Thirteen tests were performed on 10 children (median age 15.8 years, range 8.7-20.3 years) with narcolepsy, of which six had cataplexy and three were boys. Comorbid conditions included Prader-Willi syndrome, bipolar affective disorder, and epilepsy (n = 1 each). The median mean sleep latency for all studies was 16 minutes (range 5.8-40 minutes). Sleep-onset rapid eye movement sleep events were seen in three of 13 studies. In seven patients, findings from the MWT resulted in changes in management. These data suggest that the MWT may be a useful and feasible test for assessing response to treatment in children with narcolepsy. Future research is needed to obtain normative MWT data on children with and without narcolepsy.

Maintenance of Wakefulness Test scores and driving performance in sleep disorder patients and controls

OBJECTIVE

Sleepiness at the wheel is a risk factor for traffic accidents. Past studies have demonstrated the validity of the Maintenance of Wakefulness Test (MWT) scores as a predictor of driving impairment in untreated patients with obstructive sleep apnea syndrome (OSAS), but there is limited information on the validity of the maintenance of wakefulness test by MWT in predicting driving impairment in patients with hypersomnias of central origin (narcolepsy or idiopathic hypersomnia). The aim of this study was to compare the MWT scores with driving performance in sleep disorder patients and controls.

METHODS

19 patients suffering from hypersomnias of central origin (9 narcoleptics and 10 idiopathic hypersomnia), 17 OSAS patients and 14 healthy controls performed a MWT (4×40-minute trials) and a 40-minute driving session on a real car driving simulator. Participants were divided into 4 groups defined by their MWT sleep latency scores. The groups were pathological (sleep latency 0-19 min), intermediate (20-33 min), alert (34-40 min) and control (>34 min). The main driving performance outcome was the number of inappropriate line crossings (ILCs) during the 40 minute drive test.

RESULTS

Patients with pathological MWT sleep latency scores (0-19 min) displayed statistically significantly more ILC than patients from the intermediate, alert and control groups (F (3, 46)=7.47, p<0.001).

INTERPRETATION

Pathological sleep latencies on the MWT predicted driving impairment in patients suffering from hypersomnias of central origin as well as in OSAS patients. MWT is an objective measure of daytime sleepiness that appears to be useful in estimating the driving performance in sleepy patients.

Hypersomnia and depressive symptoms: methodological and clinical aspects

The associations between depressive symptoms and hypersomnia are complex and often bidirectional. Of the many disorders associated with excessive sleepiness in the general population, the most frequent are mental health disorders, particularly depression. However, most mood disorder studies addressing hypersomnia have assessed daytime sleepiness using a single response, neglecting critical and clinically relevant information about symptom severity, duration and nighttime sleep quality. Only a few studies have used objective tools such as polysomnography to directly measure both daytime and nighttime sleep propensity in depression with normal mean sleep latency and sleep duration. Hypersomnia in mood disorders, rather than a medical condition per se, is more a subjective sleep complaint than an objective finding. Mood symptoms have also been frequently reported in hypersomnia disorders of central origin, especially in narcolepsy. Hypocretin deficiency could be a contributing factor in this condition. Further interventional studies are needed to explore whether management of sleep complaints improves mood symptoms in hypersomnia disorders and, conversely, whether management of mood complaints improves sleep symptoms in mood disorders.

Evaluating sleepiness-related daytime function by querying wakefulness inability and fatigue: Sleepiness-Wakefulness Inability and Fatigue Test (SWIFT)

STUDY OBJECTIVES

Routine assessment of daytime function in Sleep Medicine has focused on "tendency to fall asleep" in soporific circumstances, to the exclusion of "wakefulness inability" or inability to maintain wakefulness, and fatigue/tiredness/lack of energy. The objective was to establish reliability and discriminant validity of a test for wakefulness inability and fatigue, and to test its superiority against the criterion standard for evaluation of sleepiness-the Epworth Sleepiness Scale (ESS).

METHODS

A 12-item self-administered instrument, the Sleepiness-Wakefulness Inability and Fatigue Test (SWIFT), was developed and administered, with ESS, to 256 adults ≥ 18 years of age (44 retook the tests a month later); consecutive patients with symptoms of sleep disorders including 286 with obstructive sleep apnea ([OSA], apnea-hypopnea index ≥ 5/h sleep on polysomnography [PSG]), 49 evaluated with PSG and multiple sleep latency test for narcolepsy and 137 OSA patients treated with continuous positive airway pressure (CPAP).

RESULTS

SWIFT had internal consistency 0.87 and retest intraclass coefficient 0.82. Factor analysis revealed 2 factors-general wakefulness inability and fatigue (GWIF) and driving wakefulness inability and fatigue (DWIF). Normal subjects differed from patients in ESS, SWIFT, GWIF, and DWIF. SWIFT and GWIF (but not DWIF) had higher area under ROC curve, Youden's index, and better positive and negative likelihood ratios than ESS. ESS, SWIFT, GWIF, and DWIF improved with CPAP. Improvements in SWIFT, GWIF, and DWIF (but not ESS) were significantly correlated with CPAP compliance.

CONCLUSIONS

SWIFT is reliable and valid. SWIFT and its factor GWIF have a discriminant ability superior to that of the ESS.

Psychometric evaluation of the Epworth sleepiness scale in an obstetric population

BACKGROUND

The Epworth Sleepiness Scale (ESS) was initially developed to measure daytime sleep propensity in patients affected by a variety of sleep disorders. Obstetrical research has measured sleepiness in pregnant women with the ESS, although psychometric analyses and dimensionality evaluations have never been conducted with this population.

OBJECTIVE

The objective was to perform a psychometric evaluation of the ESS in an obstetric population. The design was a secondary data analysis of the subjects enrolled in the Prenatal Exposures and Preeclampsia Prevention III (PEPP) study. The setting for the subjects who received prenatal care was at Magee-Women's Hospital UPMC in Pittsburgh, Pennsylvania and included 337 pregnant women in their first trimester that completed the ESS.

METHODS

Principal components analysis and confirmatory factor analysis were performed using SPSS and M-Plus. Additionally, reliability was assessed and construct validity was measured using the Life Orientation Test (LOT). Lastly, a relationship between daytime sleepiness and snoring was investigated using item 5e from the Pittsburgh Sleep Quality Index (PSQI).

RESULTS

PCA with varimax rotation yielded two factors that explained approximately 50% of the variance and CFA results verified this two-factor solution. An overall Cronbach's alpha (0.751) revealed moderate reliability (Factor 1α=.754; Factor 2α=.524). Both convergent and discriminant validity were established.

CONCLUSION

The ESS is appropriate for use in an obstetric population to measure daytime sleepiness. Future work should include additional evaluations of the ESS in a diverse group of pregnant women.

Effects of continuous positive airway pressure on neurocognitive function in obstructive sleep apnea patients: The Apnea Positive Pressure Long-term Efficacy Study (APPLES)

STUDY OBJECTIVE

To determine the neurocognitive effects of continuous positive airway pressure (CPAP) therapy on patients with obstructive sleep apnea (OSA).

DESIGN, SETTING, AND PARTICIPANTS

The Apnea Positive Pressure Long-term Efficacy Study (APPLES) was a 6-month, randomized, double-blind, 2-arm, sham-controlled, multicenter trial conducted at 5 U.S. university, hospital, or private practices. Of 1,516 participants enrolled, 1,105 were randomized, and 1,098 participants diagnosed with OSA contributed to the analysis of the primary outcome measures.

INTERVENTION

Active or sham CPAP MEASUREMENTS: THREE NEUROCOGNITIVE VARIABLES, EACH REPRESENTING A NEUROCOGNITIVE DOMAIN: Pathfinder Number Test-Total Time (attention and psychomotor function [A/P]), Buschke Selective Reminding Test-Sum Recall (learning and memory [L/M]), and Sustained Working Memory Test-Overall Mid-Day Score (executive and frontal-lobe function [E/F])

RESULTS

The primary neurocognitive analyses showed a difference between groups for only the E/F variable at the 2 month CPAP visit, but no difference at the 6 month CPAP visit or for the A/P or L/M variables at either the 2 or 6 month visits. When stratified by measures of OSA severity (AHI or oxygen saturation parameters), the primary E/F variable and one secondary E/F neurocognitive variable revealed transient differences between study arms for those with the most severe OSA. Participants in the active CPAP group had a significantly greater ability to remain awake whether measured subjectively by the Epworth Sleepiness Scale or objectively by the maintenance of wakefulness test.

CONCLUSIONS

CPAP treatment improved both subjectively and objectively measured sleepiness, especially in individuals with severe OSA (AHI > 30). CPAP use resulted in mild, transient improvement in the most sensitive measures of executive and frontal-lobe function for those with severe disease, which suggests the existence of a complex OSA-neurocognitive relationship.

CLINICAL TRIAL INFORMATION

Registered at clinicaltrials.gov. Identifier: NCT00051363.

CITATION

Kushida CA; Nichols DA; Holmes TH; Quan SF; Walsh JK; Gottlieb DJ; Simon RD; Guilleminault C; White DP; Goodwin JL; Schweitzer PK; Leary EB; Hyde PR; Hirshkowitz M; Green S; McEvoy LK; Chan C; Gevins A; Kay GG; Bloch DA; Crabtree T; Demen WC. Effects of continuous positive airway pressure on neurocognitive function in obstructive sleep apnea patients: the Apnea Positive Pressure Long-term Efficacy Study (APPLES). SLEEP 2012;35(12):1593-1602.

Diagnosis and treatment of sleep disorders: a brief review for clinicians

Sleep disorders encompass a wide spectrum of diseases with significant individual health consequences and high economic costs to society. To facilitate the diagnosis and treatment of sleep disorders, this review provides a framework using the International Classification of Sleep Disorders, Primary and secondary insomnia are differentiated, and pharmacological and nonpharmacological treatments are discussed. Common circadian rhythm disorders are described in conjunction with interventions, including chronotherapy and light therapy. The diagnosis and treatment of restless legs syndrome/periodic limb movement disorder is addressed. Attention is focused on obstructive sleep apnea and upper airway resistance syndrome, and their treatment. The constellation of symptoms and findings in narcolepsy are reviewed together with diagnostic testing and therapy, Parasomnias, including sleep terrors, somnambulism, and rapid eye movement (REM) behavior sleep disorders are described, together with associated laboratory testing results and treatment.

Daytime alertness in Parkinson's disease: potentially dose-dependent, divergent effects by drug class

Many patients with idiopathic Parkinson's disease experience difficulties maintaining daytime alertness. Controversy exists regarding whether this reflects effects of antiparkinsonian medications, the disease itself, or other factors such as nocturnal sleep disturbances. In this study we examined the phenomenon by evaluating medicated and unmedicated Parkinson's patients with objective polysomnographic measurements of nocturnal sleep and daytime alertness. Patients (n = 63) underwent a 48-hour laboratory-based study incorporating 2 consecutive nights of overnight polysomnography and 2 days of Maintenance of Wakefulness Testing. We examined correlates of individual differences in alertness, including demographics, clinical features, nocturnal sleep variables, and class and dosage of anti-Parkinson's medications. Results indicated that, first, relative to unmediated patients, all classes of dopaminergic medications were associated with reduced daytime alertness, and this effect was not mediated by disease duration or disease severity. Second, the results showed that increasing dosages of dopamine agonists were associated with less daytime alertness, whereas higher levels of levodopa were associated with higher levels of alertness. Variables unrelated to the Maintenance of Wakefulness Test defined daytime alertness including age, sex, years with diagnosis, motor impairment score, and most nocturnal sleep variables. Deficits in objectively assessed daytime alertness in Parkinson's disease appear to be a function of both the disease and the medications and their doses used. The apparent divergent dose-dependent effects of drug class in Parkinson's disease are anticipated by basic science studies of the sleep/wake cycle under different pharmacological agents.

Current and future therapeutic approaches in narcolepsy

Narcolepsy with cataplexy (NC) is a disabling orphan sleep disorder characterized by excessive daytime sleepiness, cataplexy and other dissociated manifestations of rapid eye movement sleep (hypnagogic hallucinations and sleep paralysis), as well as frequent movement and awakening during night-time sleep. In this article, we will describe the main symptoms and the current and future treatments of NC. Pathophysiological studies have shown that NC is caused by the early loss of neurons in the hypothalamus that produce hypocretin/orexin, a wakefulness-associated neurotransmitter present in cerebrospinal fluid. The cause of neural loss could be autoimmune since most patients have the human leukocyte antigen DQB1*0602 allele that predisposes individuals to NC. The treatment of narcolepsy has evolved over the past few years with the widespread use of modafinil for daytime sleepiness, antidepressants for cataplexy and γ-hydroxybutyrate (sodium oxybate) for both symptoms. Potential development of new wake-promoting drugs, anticataplectic medications, slow-wave sleep-enhancing treatments, hypocretin-replacement therapy and immunotherapy at early stages of the disease needs to be evaluated in the near future.

There and back again: a current history of sleep medicine

Sleep science has been a vigorously evolving field over the past 60 years, and the practice of sleep medicine has become increasingly complex with a growing number of tests and treatments. This article briefly traces the history of the field of sleep science over the past three millennia. The foundations of sleep medicine can be traced back to ancient civilizations around the globe. Many philosophers, scientists, and researchers have espoused theories about the causes of sleep throughout the centuries, theories that have become more intricate as our understanding of medicine and neurobiology has continued to advance.

Fatigue in multiple sclerosis is closely related to sleep disorders: a polysomnographic cross-sectional study

BACKGROUND

Sleep disorders can cause tiredness. The relationship between sleep disorders and fatigue in patients with multiple sclerosis (MS) has not yet been investigated systematically.

OBJECTIVE

To investigate the relationship between fatigue and sleep disorders in patients with MS.

METHODS

Some 66 MS patients 20 to 66 years old were studied by overnight polysomnography. Using a cut-off point of 45 in the Modified Fatigue Impact Scale (MFIS), the entire cohort was stratified into a fatigued MS subgroup (n=26) and a non-fatigued MS subgroup (n=40).

RESULTS

Of the fatigued MS patients, 96% (n=25) were suffering from a relevant sleep disorder, along with 60% of the non-fatigued MS patients (n=24) (p=0.001). Sleep-related breathing disorders were more frequent in the fatigued MS patients (27%) than in the non-fatigued MS patients (2.5%). Significantly higher MFIS values were detected in all (fatigued and non-fatigued) patients with relevant sleep disorders (mean MFIS 42.8; SD 18.3) than in patients without relevant sleep disorders (mean MFIS 20.5; SD 17.0) (p<0.001). Suffering from a sleep disorder was associated with an increased risk of fatigue in MS (odds ratio: 18.5; 95% CI 1.6-208; p=0.018).

CONCLUSION

Our results demonstrate a clear and significant relationship between fatigue and sleep disorders.

Neurobehavioral dynamics following chronic sleep restriction: dose-response effects of one night for recovery

OBJECTIVE

Establish the dose-response relationship between increasing sleep durations in a single night and recovery of neurobehavioral functions following chronic sleep restriction.

DESIGN

Intent-to-treat design in which subjects were randomized to 1 of 6 recovery sleep doses (0, 2, 4, 6, 8, or 10 h TIB) for 1 night following 5 nights of sleep restriction to 4 h TIB.

SETTING

Twelve consecutive days in a controlled laboratory environment.

PARTICIPANTS

N = 159 healthy adults (aged 22-45 y), median = 29 y).

INTERVENTIONS

Following a week of home monitoring with actigraphy and 2 baseline nights of 10 h TIB, subjects were randomized to either sleep restriction to 4 h TIB per night for 5 nights followed by randomization to 1 of 6 nocturnal acute recovery sleep conditions (N = 142), or to a control condition involving 10 h TIB on all nights (N = 17).

MEASUREMENTS AND RESULTS

Primary neurobehavioral outcomes included lapses on the Psychomotor Vigilance Test (PVT), subjective sleepiness from the Karolinska Sleepiness Scale (KSS), and physiological sleepiness from a modified Maintenance of Wakefulness Test (MWT). Secondary outcomes included psychomotor and cognitive speed as measured by PVT fastest RTs and number correct on the Digit Symbol Substitution Task (DSST), respectively, and subjective fatigue from the Profile of Mood States (POMS). The dynamics of neurobehavioral outcomes following acute recovery sleep were statistically modeled across the 0 h-10 h recovery sleep doses. While TST, stage 2, REM sleep and NREM slow wave energy (SWE) increased linearly across recovery sleep doses, best-fitting neurobehavioral recovery functions were exponential across recovery sleep doses for PVT and KSS outcomes, and linear for the MWT. Analyses based on return to baseline and on estimated intersection with control condition means revealed recovery was incomplete at the 10 h TIB (8.96 h TST) for PVT performance, KSS sleepiness, and POMS fatigue. Both TST and SWE were elevated above baseline at the maximum recovery dose of 10 h TIB.

CONCLUSIONS

Neurobehavioral deficits induced by 5 nights of sleep restricted to 4 h improved monotonically as acute recovery sleep dose increased, but some deficits remained after 10 h TIB for recovery. Complete recovery from such sleep restriction may require a longer sleep period during 1 night, and/or multiple nights of recovery sleep. It appears that acute recovery from chronic sleep restriction occurs as a result of elevated sleep pressure evident in both increased SWE and TST.

Measurements of sleepiness and fatigue

Sleepiness and fatigue are terms commonly used in clinical practice and research. At times sleepiness and fatigue are used interchangeably; however, each of them has distinct implications for diagnosis and treatment. The objective of this article is to review the psychometric properties of the measurements of sleepiness and fatigue. Although there are objective and subject measures to evaluate sleepiness, only rating scales are available to assess fatigue. Further research should be directed toward exploring the potential mechanisms underlying the measurements of sleepiness and fatigue. Establishing objective assessing instruments to evaluate fatigue and clarifying the relationship between objective and subjective assessments of sleepiness are crucially needed.

[Brazilian guidelines for the diagnosis of narcolepsy]

This manuscript contains the conclusion of the consensus meeting on the diagnosis of narcolepsy based on the review of Medline publications between 1980-2010. Narcolepsy is a chronic disorder with age at onset between the first and second decade of life. Essential narcolepsy symptoms are cataplexy and excessive sleepiness. Cataplexy is defined as sudden, recurrent and reversible attacks of muscle weakness triggered by emotions. Accessory narcolepsy symptoms are hypnagogic hallucinations, sleep paralysis and nocturnal fragmented sleep. The clinical diagnosis according to the International Classification of Sleep Disorders is the presence of excessive sleepiness and cataplexy. A full in-lab polysomnography followed by a multiple sleep latency test is recommended for the confirmation of the diagnosis and co-morbidities. The presence of two sleep-onset REM period naps in the multiple sleep latency test is diagnostic for cataplexy-free narcolepsy. A positive HLA-DQB1*0602 with lower than 110pg/mL level of hypocretin-1 in the cerebrospinal fluid is required for the final diagnosis of cataplexy- and sleep-onset REM period -free narcolepsy.

Randomized controlled trial comparing flexible and continuous positive airway pressure delivery: effects on compliance, objective and subjective sleepiness and vigilance

STUDY OBJECTIVES

Positive airway pressure (PAP) treatment for obstructive sleep apnea (OSA) can be limited by suboptimal compliance. C-Flex technology (Philips Respironics, PA, USA) reduces pressure during expiration, aiming to improve comfort and therefore compliance. This may be of particular relevance to patients requiring high pressures. Many studies thus far have suffered from design limitations and small sample sizes. This study aimed to compare compliance with C-Flex and CPAP, as well as analyzing objective and subjective sleepiness and vigilance.

DESIGN

Three-month, double-blinded, parallel-arm randomized controlled trial.

SETTING

A university-based sleep laboratory.

PATIENTS

76 consecutive patients with severe OSA (mean +/- SD AHI 60.2 +/- 32.9 events/hour, ESS 13.6 +/- 4.5/24, BMI 35.6 +/- 7.8 kg/m2), without significant cardiac, respiratory, psychiatric, or sleep comorbidities.

INTERVENTIONS

Patients were randomized to C-Flex (dip level 2) or CPAP.

MEASUREMENTS AND RESULTS

Patients underwent titration with C-Flex/CPAP (mean pressure 11.6 cm H2O). Modified maintenance of wakefulness tests (mod-MWT), psychomotor vigilance tasks (PVT) and questionnaires were administered at baseline and after one and 3 months. Median compliance was 5.51 and 5.89 h/night in the C-Flex and CPAP groups respectively (P = 0.82). There were no significant differences between groups in terms of PVT reaction time, subjective sleepiness, sleep quality, health-related quality of life, or treatment comfort. There was no significant difference between the groups regarding the change in mod-MWT sleep latency values.

CONCLUSIONS

In patients with severe OSA both CPAP and C-Flex resulted in substantial improvements in sleepiness, vigilance, and quality of life. The use of C-Flex did not result in greater compliance, and neither treatment appeared superior.

Automatic slow eye movement (SEM) detection of sleep onset in patients with obstructive sleep apnea syndrome (OSAS): comparison between multiple sleep latency test (MSLT) and maintenance of wakefulness test (MWT)

OBJECTIVE

To determine whether automatic slow eye movement (SEM) analysis performs comparably to standard sleep onset criteria at the multiple sleep latency test (MSLT) and at the maintenance of wakefulness test (MWT) in patients with obstructive sleep apnea syndrome (OSAS).

METHODS

We compared sleep latencies obtained upon standard analysis of MSLT and MWT recordings with automatically detected SEM latencies in a population of 20 severe OSAS patients that randomly underwent the two tests 1 week apart.

RESULTS

Eight of 20 OSAS patients had EDS as answered by the Epworth Sleepiness Scale (ESS). Mean SEM latency performed comparably to standard sleep onset in both the MSLT (6.4+/-5.5 min versus 7.4+/-5.1 min, p=0.25) and the MWT (25.2+/-14.5 min versus 24.4+/-14.0 min, p=0.45) settings. Mean SEM latency significantly correlated with the sleep latency at the MSLT (r=0.52, p<0.05) and at the MWT (r=0.74, p<0.001). Finally, the Epworth Sleepiness Scale score correlated with SEM latency at the MWT (r=-0.62, p<0.01), but not at the MSLT.

CONCLUSIONS

Automatic SEM detection performed comparably to standard polysomnographic assessment of sleep onset, thus providing a simplified technical requirement for the MSLT and the MWT. Further studies are warranted to evaluate SEM detection of sleep onset in other sleep disorders with excessive daytime sleepiness.

Approaches to measuring the effects of wake-promoting drugs: a focus on cognitive function

OBJECTIVES

In clinical drug development, wakefulness and wake-promotion may be assessed by a large number of scales and questionnaires. Objective assessment of wakefulness is most commonly made using sleep latency/maintenance of wakefulness tests, polysomnography and/or behavioral measures. The purpose of the present review is to highlight the degree of overlap in the assessment of wakefulness and cognition, with consideration of assessment techniques and the underlying neurobiology of both concepts.

DESIGN

Reviews of four key areas were conducted: commonly used techniques in the assessment of wakefulness; neurobiology of sleep/wake and cognition; targets of wake promoting and/or cognition enhancing drugs; and ongoing clinical trials investigating wake promoting effects.

RESULTS

There is clear overlap between the assessment of wakefulness and cognition. There are common techniques which may be used to assess both concepts; aspects of the neurobiology of both concepts may be closely related; and wake-promoting drugs may have nootropic properties (and vice versa). Clinical trials of wake-promoting drugs often, though not routinely, assess aspects of cognition.

CONCLUSIONS

Routine and broad assessment of cognition in the development of wake-promoting drugs may reveal important nootropic effects, which are not secondary to alertness/wakefulness, whilst existing cognitive enhancers may have underexplored or unknown wake promoting properties.

Daytime sleepiness and driving performance in patients with obstructive sleep apnea: comparison of the MSLT, the MWT, and a simulated driving task

STUDY OBJECTIVES

To test the reliability of a driving-simulation test for the objective measurement of daytime alertness compared with the Multiple Sleep Latency Test (MSLT) and with the Maintenance of Wakefulness Test (MWT), and to test the ability to drive safely, in comparison with on-road history, in the clinical setting of untreated severe obstructive sleep apnea.

DESIGN

N/A.

SETTING

Sleep laboratory.

PATIENTS OR PARTICIPANTS

Twenty-four patients with severe obstructive sleep apnea and reported daytime sleepiness varying in severity (as measured by the Epworth Sleepiness Scale).

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Patients underwent MSLT and MWT coupled with 4 sessions of driving-simulation test on 2 different days randomly distributed 1 week apart. Simulated-driving performance (in terms of lane-position variability and crash occurrence) was correlated with sleep latency on the MSLT and more significantly on the MWT, showing a predictive validity toward the detection of sleepy versus alert patients with obstructive sleep apnea. In addition, patients reporting excessive daytime sleepiness or a history of car crashes showed poorer performances on the driving simulator.

CONCLUSIONS

A simulated driving test is a suitable tool for objective measurement of daytime alertness in patients with obstructive sleep apnea. Further studies are needed to clarify the association between simulated-driving performance and on-road crash risk of patients with sleep disordered breathing.

Maintenance of wakefulness test in military personnel with upper airway resistance syndrome and mild to moderate obstructive sleep apnea

BACKGROUND

Sleep-disordered breathing (SDB) and the associated symptom of excessive daytime sleepiness (EDS) in military personnel has influential consequences in both the garrison and the deployed environments. The maintenance of wakefulness test (MWT) is a daytime study used to evaluate the tendency to stay awake. We evaluated consecutive patients diagnosed with mild to moderate obstructive sleep apnea (OSA) and upper airway resistance syndrome (UARS) to provide an objective measure of their EDS using the MWT.

MATERIALS AND METHODS

All military personnel referred between February 2004 and March 2005 with a clinical evaluation suspicious for SDB were evaluated with an overnight polysomnography (PSG). After overnight PSG, military personnel with mild to moderate OSA and UARS were evaluated with a 40-min protocol MWT. Abnormal MWT was defined as sleep onset latency mean below 19.4 min (<2 SD below the mean).

RESULTS

Sixty-two military personnel met entry criteria. Fifty-nine were men. Nineteen patients (32%) were diagnosed with UARS with a mean respiratory disturbance index of 11/h (5-20/h). Forty-one (68%) of the military personnel had OSA with a mean apnea-hypopnea index of 12/h (5-29/h). As a collective group, the mean Epworth Sleepiness Scale was elevated at 13/24 (1-24). This subjective excessive sleepiness was assessed with the MWT test, which resulted in a group mean MWT sleep onset latency of 27 min (5-40 min). Eighteen soldiers (30% of the total patients) had abnormal MWTs [six patients (33.3%) with UARS and 12 (67%) with OSA].

CONCLUSION

Military personnel with mild to moderate OSA and UARS often have abnormal MWTs and therefore have a pathological tendency to fall asleep. This EDS could pose a safety hazard in those personnel, military or civilian, who operate dangerous vehicles, machinery, or carry a firearm. Military personnel with untreated SDB are also at risk for the consequences of decreased mental alertness and decreased cognitive functioning due to daytime sleepiness.