Scoring reliability of the multiple sleep latency test in a clinical population

STUDY OBJECTIVES: To determine intrarater and interrater scoring reliability of the multiple sleep latency test (MSLT) in a population of sleep clinic patients. DESIGN: N/A. SETTING: Urban sleep center. PATIENTS: 200 consecutive sleep center patients (diagnoses included: obstructive sleep apnea, narcolepsy, periodic-limb-movement, and individuals with no diagnosis). INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: MSLTs were recorded and scored according to standard clinical procedures. One of four clinical polysomnographers and one of seven polysomnographic technologists scored each MSLT. All MSLTs were then rescored by the same polysomnographer. The intrarater reliability coefficient for mean MSLT score was .87 and interrater reliability was .90. Coefficients for the mean number of REM onsets during the MSLT were .81 for intrarater and .88 for interrater reliability. Intrarater and interrater agreement (kappa coefficients) for the presence of at least one REM onset during the MSLT was .78 and .86, respectively. For the presence of greater than one REM onset, a kappa of .78 was obtained for intrarater agreement and .91 for interrater agreement. CONCLUSIONS: The clinical MSLT displays excellent interrater and intrarater reliability estimates for both sleep latency and REM onset scores in a sleep-disordered population.     

Oculomotor changes are associated to daytime sleepiness in the multiple sleep latency test

Sleep onsets in the diurnal multiple sleep latency test (MSLT), following different sleep lengths of the preceding night sleep (8, 5, 4, 3, 2, 1 h) and following the corresponding recovery nights, were considered for a study on changes of oculomotor activity during sleep onset. The study aimed to assess the individual time course in spontaneous blinks (SBs) and slow eye movements (SEMs) during the sleep onset period and also the relationship with sleep latencies in the MSLT. Group analyses compared oculomotor changes between conditions characterized by a different level of daytime sleepiness. The results show a clear inverse relation between the two oculomotor measures, with a linear SB decrease and quadratic SEM increase across the wake-sleep transition. A 150 s sample of SB and SEM activity at the start of MSLT trials correlates with individual subsequent sleep latency. Finally, mean changes in daytime sleepiness as measured by the MSLT are paralleled by coherent oculomotor changes, with a significant linear decrease of SB as sleepiness increases as a consequence of previous sleep reduction. Both individual and group results show that endogenous blinking is associated with moderate changes in daytime sleepiness.     

发作性睡病的临床特征及多次小睡潜伏期试验

目的：探讨发作性睡病的临床特征及多次小睡潜伏期试验(MSLT)在诊断发作性睡病中的作用。方法：对6例发作性睡病的诊断过程进行回顾性分析。结果：6例患者均有白天过度嗜睡．其中4例伴猝倒。首发症状为白天过度嗜睡5例。猝倒1例。以白天过度嗜睡就诊者3例，以猝倒就诊者3例。6例患者进行MSLT检查，所有患者平均睡眠潜伏期都小于5min．其中5例出现≥2次的睡眠始发REM睡眠(SOREMS)。结论：充分认识发作性睡病的临床特征是诊断的关键。对于临床表现不典型的病例，MSLT将有助于诊断。     

Assessing the efficacy to conduct the multiple sleep latency test with actigraphy

This study explored the efficacy of 1 actigraphy (ACT) brand, at different analytic settings, for use to administer the Multiple Sleep Latency Test (MSLT). Forty-one first-time postpartum mother and father participants were administered the MSLT with concurrent ACT. To identify ACT sleep onset latency (SOL), ACT signals were interpreted with iterations of different "wake threshold value" (WTV) and "immobile minutes for sleep onset" value (IMV) settings. The different iterations of ACT-SOL values were compared to MSLT-SOL values. The WTV settings did not affect ACT-SOL, but the ACT-SOL and MSLT-SOL significantly differed at each ACT-IMV setting. ACT consistently identified SOL too soon; however, future research, along with technological innovation, may identify a viable methodology to conduct an ambulatory MSLT.     

Sleep perception and the multiple sleep latency test in patients with primary insomnia

The purpose of this study was to examine the relationship between overnight sleep perception and the daytime multiple sleep latency test (MSLT) among individuals who were primary insomnia patients (PIPs) or good sleeper controls (GSCs). We collected overnight sleep data via polysomnography (PSG), subjective sleep data via a morning questionnaire (self‐evaluated) and MSLT data via four 20‐min naps over 8 h. Subjects included 122 PIPs and 48 GSCs. Sleep perception was calculated as subjective sleep time/objective sleep time × 100%. PIPs showed a significant difference (P < 0.001) between sleep time, as determined by PSG (387.8 ± 100 min) and self‐report (226.3 ± 160 min), but no difference was obtained for GSCs (440.6 ± 53 versus 435.4 ± 65 min). The means for sleep perception were 56.4 ± 38.8% for the PIPs and 99.3 ± 13.6% for the GSCs (P < 0.001). In the PIPs group, weak but statistically significant negative correlations (r: ?0.20 to ?0.25) were found for MSLT versus sleep perception and versus self‐ and PSG‐evaluated sleep time. Compared to PIPs with low scores on the MSLT, those with high scores had less sleep perception (%), less self‐ and PSG‐evaluated sleep time and greater sleep misperception time. GSCs did not show significant correlations between MSLT and sleep measures or differences in comparisons between individuals with high and low scores on the MSLT. These results add novel data to the literature by suggesting that 24‐h hyperarousal potentially plays a key role in the pathophysiological issues of insomnia.     

Assessing sleepiness in the rat: a multiple sleep latencies test compared to polysomnographic measures of sleepiness

Sleepiness following 6 h of sleep deprivation (SD) was evaluated with a rat multiple sleep latencies test (rMSLT), and the findings were compared to conventional polysomnographic measures of sleepiness. The 6 h of SD was produced by automated activity wheels, and was terminated at either the end of the light period or at the beginning of the dark period. The rMSLT consisted of 5 min wakefulness induced by sensory stimulation followed by 25 min of freedom to sleep. This procedure was repeated every 30 min for 3 h and was designed to minimize the amount of sleep lost due to the testing procedure. In separate rats, 6 h SD was followed by undisturbed recovery, allowing evaluation of conventional polysomnographic measures of sleepiness. Sleep onset latencies were reduced following SD, with recovery in the light (baseline = 8 min, 3 s versus post-SD = 1 min, 17 s) and dark period (baseline = 14 min, 17 s versus 7 min, 7 s). Sleep onset latencies were not altered by varying the duration criterion for the first sleep bout (i.e., sleep bout length criteria of 10, 20, 30, or 60 s were compared). Polysomnographic variables (non-rapid eye movement sleep episode duration, delta power, and number of awakenings) also provided reliable indirect measures of sleepiness, regardless of whether the recovery sleep occurred in the light or dark period. Evaluation of effect size indicated that the rMSLT was a strong measure of sleepiness, and was influenced by homeostatic, circadian, and illumination factors. The rMSLT provided a simple, objective, robust and direct measure of sleepiness that was as effective as conventional polysomnographic measures of sleepiness.     

The impact of music upon sleep tendency as measured by the multiple sleep latency test and maintenance of wakefulness test

Previous work has shown that background noise or music has a small positive impact on performance during sleep deprivation. The current study examined the effect of background music on the ability to fall asleep or remain awake. Twelve normal-sleeping young adults took multiple sleep latency tests (MSLT) and maintenance of wakefulness tests (MWT) after baseline sleep and one night of total sleep deprivation either with background music or under standard (quiet) conditions. It was hypothesized that the music would help maintain wakefulness both under baseline and sleep deprivation conditions. The results of the study showed that sleep latencies were increased in both MSLT and MWT when music was presented, but that this effect occurred primarily before subjects were sleep-deprived (a significant Music by Sleep Deprivation interaction). Sleep latencies were 15 and 11 min on the MSLT (33 and 26 min on the MWT) with Music as compared to Quiet after baseline sleep. Heart rate, used as a measure of physiological arousal, was significantly elevated in MWT and MSLT trials where music was presented. These data support previous work showing that level of arousal has an impact on measured sleep tendency which is independent of that of the sleep system. On a practical level, these data indicate that music may play a small beneficial role in helping to maintain arousal.     

Sensitivity and specificity of the multiple sleep latency test (MSLT), the maintenance of wakefulness test and the epworth sleepiness scale: failure of the MSLT as a gold standard

Excessive daytime sleepiness (EDS) is an important symptom that needs to be quantified, but there is confusion over the best way to do this. Three of the most commonly used tests: the multiple sleep latency test (MSLT), the maintenance of wakefulness test (MWT) and the Epworth sleepiness scale (ESS) give results that are significantly correlated in a statistical sense, but are not closely related. The purpose of this investigation was to help clarify this problem. Previously published data from several investigations were used to calculate the reference range of normal values for each test, defined by the mean+/-2 SD or by the 2.5 and 97.5 percentiles. The 'rule of thumb' that many people rely on to interpret MSLT results is shown here to be misleading. Previously published results from each test were also available for narcoleptic patients who were drug-free at the time and who by definition had EDS. This enabled the sensitivity and specificity of the three tests to be compared for the first time, in their ability to distinguish the EDS of narcolepsy from the daytime sleepiness of normal subjects. The receiver operator characteristic curves clearly showed that the ESS is the most discriminating test, the MWT is next best and the MSLT the least discriminating test of daytime sleepiness. The MSLT can no longer be considered the gold standard for such tests.     

Diagnosis of narcolepsy using the multiple sleep latency test: analysis of current laboratory criteria

Multiple sleep latency tests (MSLT) performed on 144 patients with excessive daytime somnolence were examined for the diagnostic reliability of a short sleep latency (SL less than 5 min) and the presence of sleep-onset REM periods (SOREMPs). Based on clinical criteria, 61 patients (42%) were diagnosed as having narcolepsy. Thirty-five narcoleptic patients and five nonnarcoleptic patients exhibited a mean SL less than 5 min, yielding a sensitivity of 57% and a specificity of 94% for this criterion for pathological drowsiness. The occurrence of two or more SOREMPs was found in 52 narcoleptic patients but in only one nonnarcoleptic patient (sensitivity of 84% and specificity of 99%). Those narcoleptic patients with cataplexy demonstrated a shorter SL and more frequent SOREMPs than their noncataplectic counterparts. It was concluded that the MSLT is a highly reliable laboratory tool for the confirmation of the diagnosis of narcolepsy based on the SOREMP criterion. The criterion value for SL in pathological drowsiness may depend on laboratory conditions as well as the patient population selected.     

短半衰期催眠药对失眠症患者白天多次睡眠潜伏期测定的影响

目的 :探讨两种短半衰期催眠药佐匹克隆和三唑仑对失眠患者白天多次睡眠潜伏期测定 (MSLT)的影响。方法 :按照ICD 10的诊断标准收集 2 2例非器质性失眠症患者 ,随机分为两组 ,在服用 0 5mg三唑仑或 15mg佐匹克隆前后 ,分别进行MSLT检测。结果 :两药均可使白天MSLT的平均睡眠潜伏期和前两次测定的睡眠潜伏期明显缩短 ,使REM睡眠增加。两药对MSLT的影响特点相似。结论 :催眠药物可使失眠患者白天的困倦程度明显增高 ,这可能与药物的受体后效应有关 ,与药物种类的关系不大。     

The Epworth sleepiness scale: Reliably unreliable in a sleep clinic population

The Epworth Sleepiness Scale is used frequently to measure excessive daytime sleepiness in research and clinical settings, although there is limited evidence on test–retest reliability, particularly among sleep clinic populations. The objective of this study was to evaluate the reliability of this instrument among adult patients recruited from a public hospital sleep clinic in Sydney, Australia. English‐speaking participants self‐completed the Epworth Sleepiness Scale on two occasions, at the specialist clinic visit and on the night of diagnostic polysomnography. Of the 108 participants included in the study, the majority were male (64%) and the mean age was 51 years. The median retest interval was 64 days. The primary outcome of test–retest reliability as measured using the intraclass correlation coefficient was 0.73 (95% confidence interval, 0.61–0.82). Despite moderate statistical reliability and a low mean difference of 1.1, Bland‐Altman analysis showed an unacceptably wide distribution of between‐score differences. The 95% limits of agreement were ?8.5 to +10.6, and an absolute difference in scores of at least 3 was observed in 60 (56%) of the participants. Our results suggest that the Epworth Sleepiness Scale should not be used in clinical settings to make individual‐level comparisons, such as the effect of therapeutic interventions, or to prioritise access to services.     

A comparison of multiple and single sleep latency and cerebral evoked potential (P300) measures in the assessment of excessive daytime sleepiness in narcolepsy-cataplexy

A direct comparison was made between the amplitude of evoked potential (EP) component P3 (by the P300 paradigm), a known sensitive EP correlate of sleepiness, and sleep latency measures (both to stage 1 or rapid eye movement [REM] and to stage 2 or REM) of the Multiple Sleep Latency Test (MSLT) in 11 untreated narcoleptics and matched controls. Repeated P3 measures were performed immediately prior to standard MSLT naps at 10:00 a.m., 12:00 noon, 2:00 p.m., 4:00 p.m., and 6:00 p.m. Using discriminant analysis and F tests, all three measures (P3 and both by MSLT) were found to distinguish the two groups for collapsed five-nap data, and all showed essentially parallel circadian time-of-day effects, with greatest sleepiness in the midafternoon. The MSLT, however, was somewhat more powerful for collapsed data. Both tests misclassified some subjects as belonging to the other group, with greater misclassification for both tests in the control group and more overall for the P3 measure. Adding the two sleep onset REM period (SOREMP) criteria on MSLT for narcolepsy, one patient was still classified as normal. Analysis of data from individual naps indicated that the MSLT was considerably more powerful in discriminating groups than was P3 amplitude, and it did so for all five naps.     

Factors associated with maintenance of wakefulness test mean sleep latency in patients with mild to moderate obstructive sleep apnoea and normal subjects

This study investigated the possible factors related to the Maintenance of Wakefulness Test (MWT) mean sleep latency. A second analysis explored the characteristics of subjects who had discrepant Epworth Sleepiness Scale (ESS) and MWT scores. A total of 151 subjects (110 mild to moderate obstructive sleep apnoea (OSA) patients and 41 control subjects) were recruited for the study. The subjects completed an overnight Polysomnography (PSG), MWT, cognitive, performance and vigilance tasks and answered self-report questionnaires on mood and sleepiness. A forward stepwise multiple regression was performed on MWT mean sleep latency. The predictor variables age (r = 0.28), subjective sleep history for 1 week prior to MWT (sleep diary; r = 0.19) and number of >4% SaO2 Dips during the PSG (r = -0.21) best explained the MWT results, but only accounted for 12.8% of the variance in the test. It was found that 33% of subjects had discrepant ESS and MWT scores. A new variable was created to analyse these subjects (MWT/ESS discrepancy score; MED). A forward stepwise multiple regression analysis found that depression, performance errors and sleep disordered breathing explained 13.4% of the variance in MED scores. The MWT is a complex behavioural test whose scores do not seem to have a very robust relationship with potential predictors and co-correlates. Further comprehensive study is needed if the test is to be used in a diagnostically meaningful way.     

Incidence of sleep apnea in a presumably healthy working population: a significant relationship with excessive daytime sleepiness

Seventy-eight workers, drawn from a population of 1502 presumably healthy working men who were interviewed about sleep habits and sleep disorders, underwent polygraphic recordings for at least 1 night. A significant association was found between the complaint of excessive daytime sleepiness and the incidence of sleep apnea. Workers with more than 10 apneas per hour of sleep complained significantly more about loud snoring, hypermotility in sleep, and frequent headaches. They had significantly more ENT findings and hypertension.     

Incidence of sleep apnea in a presumably healthy working population: a significant relationship with excessive daytime sleepiness

Seventy-eight workers, drawn from a population of 1502 presumably healthy working men who were interviewed about sleep habits and sleep disorders, underwent polygraphic recordings for at least 1 night. A significant association was found between the complaint of excessive daytime sleepiness and the incidence of sleep apnea. Workers with more than 10 apneas per hour of sleep complained significantly more about loud snoring, hypermotility in sleep, and frequent headaches. They had significantly more ENT findings and hypertension.     

Association of hostility with sleep duration and sleep disturbances in an employee population

Background: Sleep disturbances are common among the general population, and hostile persons have been proposed to be at greater risk of several serious health problems and diseases. Purpose: This study examined the relationships between hostility, sleep disturbances, and sleep duration in a large non-clinical sample of 5,433 employees working in 12 Finnish hospitals. Method: Data were collected by questionnaire surveys in 1998 and 2000. Results: Higher hostility was cross-sectionally associated with increased sleep disturbances but not with sleep duration after adjustment for gender, age, marital status, education, shift work, smoking, alcohol consumption, physical activity, body mass index, psychiatric morbidity, and somatic disease. A stratified analysis distinguishing individuals with stable hostility across the two measurements and those with transient hostility (>0.5 SD difference between measurements) replicated the association with increased sleep disturbance in both groups, but among those with transient hostility, there additionally was a cross-sectional association between higher hostility and shorter sleep duration. Conclusion: Our evidence suggests that hostility is an independent risk factor for sleep disturbances and that transient hostility may also predispose shorter sleep duration. However, the effect sizes for all these associations were small, suggesting limited clinical significance for our findings.     

Wais prediction for an older clinical population using the quick test

Data were analyzed to estimate WAIS Full Scale IQs from Quick Test scores. Ss were 26 mental health center patients raning in age from 46 to 78 years (X= 58.46, SD = 8.78). In predicting WAIS Full cale IQs, Quick Test Form 3 age-corrected and uncorrected score accounted for 66 and 70% of the variance respectively (p < 0.001). Two- and three-variable regression models did not yield meaningful increases in variance. Quick Test Form 3 is recommended when a brief measure of intellectual functioning for an aged clinical population is needed.