Baseline Polysomnogram Research Articles

The nightly administration of sodium oxybate results in significant reduction in the nocturnal sleep disruption of patients with narcolepsy

Previous studies indicate that nightly sodium oxybate administration reduces nocturnal sleep disruption in narcolepsy. The present study provided an opportunity to further characterize these sleep-related effects in patients with narcolepsy during treatment with sodium oxybate as monotherapy or in combination with modafinil. This double-blind, placebo-controlled study enrolled 278 patients with narcolepsy taking modafinil 200-600 mg daily for the treatment of excessive daytime sleepiness (EDS). Following a baseline polysomnogram (PSG) and Maintenance of Wakefulness Test (MWT), patients were randomized to receive treatment with: (1) placebo, (2) sodium oxybate, (3) modafinil, or (4) sodium oxybate+modafinil. PSGs and MWTs were repeated after 4 and 8 weeks. Other efficacy measures included Epworth Sleepiness Scale scores and daily diary recordings. After 8 weeks, significant changes in sleep architecture among patients receiving sodium oxybate and sodium oxybate/modafinil included a median increase in Stage 3 and 4 sleep (43.5 and 24.25 min, respectively) and delta power and a median decrease in nocturnal awakenings (6.0 and 9.5, respectively). No significant changes in PSG parameters were noted in patients treated with placebo or modafinil alone. In addition to its established efficacy for the treatment of cataplexy and EDS, nightly sodium oxybate administration significantly reduces measures of sleep disruption and significantly increases slow-wave sleep in patients with narcolepsy.

Apnea is exacerbated following exposure to intermittent hypoxia and is mitigated following administration of an antioxidant cocktail

PurposeTo determine whether exposure to intermittent hypoxia (IH) exacerbates apnea severity and whether administration of an antioxidant cocktail (AOX) mitigates this response.MethodsTwo studies were completed. Ten participants with OSA completed study 1 while 5 participants completed study 2. Study 1 required two visits while study 2 required 3 visits. For both studies, a baseline polysomnogram with no intervention was completed initially. During the remaining visits of both studies, participants were exposed to IH {12‐4 minute episodes of hypoxia (PETO2‐ 50 mmHg, PETCO2 ‐ 3 mmHg above baseline)} immediately followed by a sleep study. During visits 2 and 3 of study 2 participants were administered either an AOX or Placebo (PLB) in a randomized blinded fashion. Breathing events were scored during the initial 3 hours of sleep.ResultsStudy 1 ‐ The apnea/hypopnea index (AHI) after exposure to IH was greater compared to baseline (43.3 ± 5.3 vs. 34.6 ± 3.2 events/hr, p = 0.04). Study 2 ‐ Similar results were observed when the AHI during PLB was compared to baseline (43.4 ± 6.2 vs. 27.6 ± 7.8 events/hr, p = 0.01). In contrast, the AHI during the PLB trial was greater compared to the AHI following AOX administration (43.4 ± 6.2 vs. 31.8 ± 5.7 events/hr, p = 0.04).ConclusionsExposure to IH may lead to an increase in the AHI while administration of an antioxidant cocktail may mitigate the increase.FundingNIH (HL‐085537)

Children Show Individual Night-to-Night Variability of Periodic Limb Movements in Sleep

Several studies have documented the occurrence of significant night-to-night variability of periodic limb movements in sleep (PLMS) in adults.The aim of this study was to investigate the night-tonight variability of PLMS in children. Two to 4 nights of polysomnography were performed as part of a multisite, placebo-controlled study investigating the effects of carbidopa/levodopa on attention-deficit/hyperactivity disorder in children who were not taking other medications that impacted the central nervous system. Baseline polysomnograms from all children and endpoint polysomnograms from children who were randomly assigned to a placebo group were scored using International Restless Legs Syndrome Study Group criteria for PLMS. PLMS indexes from 101 sleep studies of 36 children, aged 7 to 12 years, were compared. N/A. For all 36 children as a group, PLMS index on Night 1 was predictive of PLMS index on Night 2 (odds ratio 7.0, 95% confidence interval 1.4-38.4), suggesting that overall diagnostic classification (PLMS index above or below 5/h) was accurate. In addition, for the 15 children with 5 or more PLMS per hour on either night, there was no significant group difference on Night 1 versus Night 2 for mean PLMS index (10.6 vs 8.5/h, P = 0.92) or chance of having 5 or more PLMS per hour, indicating no first-night effect. When looking at individual data, however, 9 of these 15 children (60%) had PLMS indexes over and under the 5 per hour cutoff on these 2 nights. Of these 15, 10 had clinical diagnoses of restless legs syndrome and 5 of periodic limb movement disorder (PLMD). The PLMS indexes of all children who were medication free for a third and fourth night (n = 7) or just a third night (n = 2) and had not shown a PLMS index of 5 or greater on either of the first 2 nights remained under this threshold. In this sample of children, considerable individual night-to-night variability of PLMS indexes was observed. This finding has important clinical relevance for the diagnosis of restless legs syndrome and PLMD and may have an impact on future studies that correlate individual PLMS severity with frequently associated symptoms, such as negative affect, fatigue, and inattention. Our data, however, also suggest that individual PLMS variability is random and not likely to skew the group-level analysis of treatment outcome studies.

Arousal frequency is associated with increased fatigue in obstructive sleep apnea.

ObjectiveFatigue is an important and often underemphasized symptom in patients with obstructive sleep apnea (OSA). Sleep fragmentation, i.e., arousals and disruptions in sleep architecture, is common in patients with OSA and may potentially contribute to their fatigue. We hypothesized that arousal frequency and changes in sleep architecture contribute to the fatigue experienced by patients with OSA.DesignSeventy-three patients with diagnosed but untreated OSA (AHI ≥ 15) were enrolled in this study. A baseline polysomnogram was obtained, and fatigue was measured with the Multidimensional Fatigue Symptom Inventory-short form (MFSI-sf). We evaluated the association between fatigue and arousals and various polysomongraphic variables, including sleep stages and sleep efficiency.ResultsSignificant correlations between MFSI-sf subscale scores and various arousal indices were noted. Emotional fatigue scores were associated with total arousal index (r = 0.416, p = .021), respiratory movement arousal index (r = 0.346, p = .025), and spontaneous movement arousal index (r = 0.378, p = .025). Physical fatigue scores were associated with total arousal index (r = 0.360, p = .033) and respiratory movement arousal index (r = 0.304, p = .040). Percent of stage 1 sleep and REM sleep were also associated with physical and emotional fatigue scores. Hierarchal linear regression analysis demonstrated that emotional fatigue scores were independently associated with spontaneous movement arousals after controlling for age, body mass index, depression, and sleep apnea severity.ConclusionsThese findings suggest that arousals may contribute to the fatigue seen in patients with OSA.

The roles of TNF-α and the soluble TNF receptor I on sleep architecture in OSA

ObjectivePatients with obstructive sleep apnea (OSA) have been described to have increased levels of inflammatory cytokines (particularly TNF-α) and have severely disturbed sleep architecture. Serum inflammatory markers, even in normal individuals, have been associated with abnormal sleep architecture. Not much is known about the role the TNF receptor plays in the inflammation of OSA nor if it is associated with changes in sleep architecture or arousals during the night. We hypothesized that the TNF receptor might play an important role in the inflammation as well as sleep architecture changes in patients with OSA.DesignThirty-six patients with diagnosed (AHI > 15) but untreated OSA were enrolled in this study. Baseline polysomnograms as well as TNF-α and soluble TNF receptor I (sTNF-RI) serum levels were obtained on all patients. We evaluated the association between serum levels of TNF-α and sTNF-RI with various polysomongraphic characteristics, including sleep stages and EEG arousals.ResultssTNF-RI levels were significantly correlated with snore arousals (r value 0.449, p value 0.009), spontaneous movement arousals (r value 0.378, p value 0.025), and periodic limb movement arousals (r value 0.460, p value 0.008). No statistically significant correlations were observed with TNF-α to any polysomnographic variables. To control for statistical significance with multiple comparisons, a MANOVA was performed with TNF-α and sTNF-RI as dependent variables and sleep architecture measures and arousals as independent variables. The model for sTNF-RI was statistically significant (F value 2.604, p value 0.03), whereas the model for TNF-α was not, suggesting sleep quality significantly affects sTNF-RI. Hierarchal linear regression analysis demonstrated that sTNF-RI was independently associated with spontaneous movement arousal index scores after controlling for age, body mass index, and sleep apnea severity.ConclusionsThese findings suggest that sTNF-RI is associated with arousals during sleep, but not with other measures in patients with OSA.

Sleep staging and respiratory events in refractory epilepsy patients: Is there a first night effect?

We performed this analysis of possible first night effects (FNEs) on sleep and respiratory parameters in order to evaluate the need for two serial night polysomnograms (PSGs) to diagnose obstructive sleep apnea (OSA) in epilepsy patients. As part of a pilot multicenter clinical trial investigating the effects of treating sleep apnea in epilepsy, two nights of PSG recording were performed for 40 patients with refractory epilepsy and OSA symptoms. Sleep architecture was examined in detail, along with respiratory parameters including apnea/hypopnea index (AHI) and minimum oxygen saturation. Analysis included two-tailed t-tests, Wilcox sign rank analysis, and Bland Altman measures of agreement. Total sleep time differed between the two nights (night 1,363.8 min + 59.4 vs. 386.3 min + 68.6, p = 0.05). Rapid eye movement (REM) sleep and percentage of REM sleep were increased during night two (night 1: 12.3% + 5.9 vs. night 2: 15.5% + 6.2, p = 0.007), and the total minutes of slow-wave sleep (SWS) were increased (night 1: 35.6 + 60.7 vs. night 2: 46.4 + 68.1, p = 0.01). No other sleep or respiratory variables differed between the two nights. Given an AHI inclusion criterion of five apneas per hour, the first PSG identified all but one patient with OSA. Respiratory parameters showed little variability between the first and second nights. Sleep architecture was mildly different between the first and second PSG night. Performing two consecutive baseline PSGs to diagnose OSA may not be routinely necessary in this population.

Central Sleep Apnea on Commencement of Continuous Positive Airway Pressure in Patients With a Primary Diagnosis of Obstructive Sleep Apnea-Hypopnea

Central sleep apnea (CSA) may occur in patients with snoring and obstructive sleep apnea-hypopnea (OSAH) during commencement of continuous positive airway pressure (CPAP) therapy. The presence of CSA may limit the effectiveness of CPAP therapy. The aims of this study were to assess the prevalence of CSA amongst patients starting CPAP for OSAH and to identify possible predictors of this condition. We reviewed the polysomnograms (PSGs) and clinical records of 99 consecutive patients with a primary diagnosis of OSAH who were referred for an in-laboratory CPAP titration study. Patients with a CSA Index of > or =5 per hour at or near (+/-1 cm H2O) prescribed CPAP level formed the CSA-CPAP group. The remaining patients made up the noCSA-CPAP group. Demographic, baseline and CPAP titration PSG variables were compared between the 2 two groups. 13 subjects (13.1%) had CSA-CPAP. Patients with and without CSA-CPAP did not differ with respect to age or body mass index. 46% of patients with CSA-CPAP had CSA on their baseline PSGs compared with 8% in the noCSA-CPAP group (p <0.01). CSA-CPAP patients also had a higher apnea-hypopnea index (72.1 vs. 52.7 p = 0.02), a higher arousal index (43.3 vs. 29.2 p <0.01), and a higher mixed apnea index (6.8 vs. 1.3 p = 0.03), on their baseline PSGs. Therapeutic CPAP could not be determined in 2 CSA-CPAP patients due to a very high frequency (of severe) central apneas. In the remaining 11, the CPAP prescription to eliminate obstructive events was higher than in the noCSA-CPAP group (11.0 vs. 9.3 p = 0.08). AHI was greater both at or near prescribed CPAP (48.8 vs. 6.7 p <0.01) and overall (47.4 vs. 14.9 p <0.01). A history of ischemic heart disease or heart failure was more frequent amongst patients with CSA-CPAP than those without (p = 0.03). A significant minority of patients with a primary diagnosis of OSAH have either emergence or persistence of CSA on CPAP. Risk factors include male sex, history of cardiac disease, and CSA on baseline PSG.

Sodium Oxybate Improves Excessive Daytime Sleepiness in Narcolepsy

To assess the effectiveness of sodium oxybate therapy, modafinil therapy and the combination of the two for excessive daytime sleepiness in narcolepsy patients previously taking modafinil. Double-blind, placebo-controlled, multicenter study. Forty-four sites in the United States, Canada, the Czech Republic, France, Germany, the Netherlands, Switzerland, and the United Kingdom. Two hundred seventy- adult patients with narcolepsy taking 200 to 600 mg of modafinil daily for the treatment of excessive daytime sleepiness. Patients received unchanged doses of modafinil (with sodium-oxybate placebo) during a 2-week baseline phase. Following a baseline polysomnogram and Maintenance of Wakefulness Test, they were randomly assigned to 1 of 4 treatment groups: sodium-oxybate placebo plus modafinil placebo, sodium oxybate plus modafinil placebo, modafinil plus sodium-oxybate placebo, or sodium oxybate plus modafinil. Sodium oxybate was administered as 6 g nightly for 4 weeks and was then increased to 9 g nightly for 4 additional weeks. The primary efficacy measure was the Maintenance of Wakefulness Test; secondary measures included the Epworth Sleepiness Scale, diary recordings, and the Clinical Global Impression-change scale. Following the switch from modafinil to placebo, the mean average daytime sleep latency on the Maintenance of Wakefulness Test decreased from 9.74 minutes at baseline to 6.87 minutes after 8 weeks (p < .001). In the sodium-oxybate group, there was no decrease in sleep latency, suggesting that this drug was as efficacious in treating the excessive daytime sleepiness as the previously administered modafinil. In contrast, the sodium-oxybate/modafinil group demonstrated an increase in daytime sleep latency from 10.43 minutes to 13.15 minutes (p < .001), suggesting that this combination of drugs produced an additive effect. The sodium-oxybate group also demonstrated a decrease in median average Epworth Sleepiness Scale scores, from 15 to 12.0, whereas the sodium-oxybate/modafinil group decreased from 15.0 to 11.0 (for both, p < .001). The Clinical Global Impression-Change scale demonstrated similar results. Sodium oxybate and modafinil are both effective for treating excessive daytime sleepiness in narcolepsy, producing additive effects when used together. Sodium oxybate is beneficial as both monotherapy and as adjunctive therapy for the treatment of excessive daytime sleepiness in narcolepsy.

Subclinical rhythmic electrographic discharge of adults (SREDA) in REM sleep

We describe the first reported case of subclinical rhythmic electrographic discharge of adults (SREDA) during rapid eye movement (REM) sleep. This 48-year-old man, with a history of witnessed apneic spells, was sent for a baseline polysomnogram. Besides demonstrating obstructive sleep apnea, his study showed the occurrence of paroxysmal delta waves evolving into a theta frequency during REM sleep. A repeat polysomnogram with 16-channel electroencephalography confirmed SREDA in the bilateral temporal/parietal regions during REM sleep. This uncommon paroxysmal electrographic pattern should not be mistaken for seizure activity and is now recognized to occur in all stages of sleep, including REM.

Effects of vagus nerve stimulation on sleep-related breathing in epilepsy patients.

To describe the effects of vagus nerve stimulation (VNS) on sleep-related breathing in a sample of 16 epilepsy patients. Sixteen adults with medically refractory epilepsy (nine men, seven women, ages 21-58 years) underwent baseline polysomnograms (PSGs). Three months after VNS therapy was initiated, PSGs were repeated. In addition, patient 7 had a study with esophageal pressure monitoring, and patient 1 had a continuous positive airway pressure (CPAP) trial. Baseline PSGs: One of 16 patients had an apnea-hypopnea index (AHI) >5 (6.8). Treatment PSGs: Five of 16 patients had treatment AHIs >5. Respiratory events were more frequent during periods with VNS activation (on-time) than without VNS activation (off-time; p = 0.016). Follow-up studies: Esophageal pressure monitoring in patient 7 showed crescendos in esophageal pressure during VNS activation, supporting an obstructive pattern. The CPAP trial of patient 1 showed that all respiratory events were associated with VNS stimulation at low CPAP levels. They were resolved at higher CPAP levels. Treatment with VNS affects respiration during sleep and should be used with care, particularly in patients with preexisting obstructive sleep apnea. The AHI after VNS treatment remained <5 in the majority of patients and was only mildly elevated (<12) in five patients. In one patient, CPAP resolved VNS-related respiratory events.

Role of cardiac pacing in sleep apnea uncertain: Article reviewed: S. Garrigue, P. Bordier, P. Jais, et al., Benefit of atrial pacing in sleep apnea syndrome, N Engl J Med, 346 (2002) 404–412

Abstract Objectives : To determine the effect of atrial overdrive pacing on sleep apnea severity in patients with sinus node dysfunction. Study design : Unblinded, cross-over study of the effect of atrial pacing on sleep apnea–hypopnea, with randomized order of study conditions (paced versus unpaced). Study population : Fifteen patients (11 men, 4 women), mean age 69 (SD 9) years, with sinus node dysfunction and permanent dual-chamber pacemakers, with polysomnographic evidence of either central or obstructive sleep apnea–hypopnea (mean apnea–hypopnea index (AHI) 27 (SD 16)). None had symptomatic heart failure, but 11 (73%) had mildly reduced left ventricular ejection fraction (40–56%). Methods : One hundred and fifty-two patients with pacemakers implanted at least one year previously for symptomatic sinus node dysfunction (including tachycardia–bradycardia syndrome) were screened for symptoms of sleep apnea. Of 47 patients identified, 26 underwent polysomnography and 15 had an apnea index >5/h and an AHI >15/h. Following the baseline polysomnogram, subjects underwent polysomnography on the subsequent two nights under the following conditions, in random order: (1) pacemaker set at a rate 15beats/min higher than the mean heart rate of the diagnostic study (overdrive pacing phase); and (2) pacemaker rate reduced to 40beats/min (no-pacing phase). The main outcome measure was the difference in AHI between the two pacing modes. Results : Mean nocturnal heart rate during the pacing phase was 72/min, versus 51/min during the no-pacing phase. During the no-pacing phase, AHI was unchanged from the baseline night at 28/h (SD 22). During overdrive pacing, however, the AHI was 61% lower at 11/h (SD 14). The AHI was lower on the pacing than the no-pacing night in all 15 subjects, regardless of whether the predominant type of apnea was central or obstructive. The mean central apnea index fell from 13 (SD 17) to 6 (SD 7), and the obstructive apnea index from 6 (SD 4) to 3 (SD 1). Both lowest oxyhemoglobin saturation and the percent time at saturation below 90% also improved on the pacing night. There was little difference in total sleep time between pacing and no-pacing nights; other measures of sleep quality were not reported. Conclusions : The authors conclude that atrial overdrive pacing at a relatively modest rate causes a substantial improvement in both central and obstructive sleep apnea, by mechanisms that are uncertain.

Validación de estudios polisomnográficos de mitad de la noche en el síndrome de apneas/hipoapneas durante el sueño

A diagnosis of sleep apnea/hypopnea syndrome (SAHS) is based on clinical signs and nighttime polysomnograms. Brief polysomnography has been proposed as an alternative to all-night recording. The aim of this study was to determine whether a polysomnograms obtained during the first half of the night is sufficient for establishing a diagnosis of SAHS and to determine the correlation between polysomnographic variables recorded during the first four hours (half the study time) with those recorded over the full eight hours (full study time), as well as to determine diagnostic agreement. Thirty-five patients suspected of having SAHS were studied prospectively. Baseline polysomnograms were scored blindly by two independent observers following standard methods. A diagnosis of SAHS was made according to guidelines of the Spanish Society of Pneumology and Chest Surgery. During the first half of the night and up to the end of each recording period we gathered neurophysiological and respiratory variables and diagnostic impressions. The correlation between variables (sleep stage, overall AHI, REM-AHI, non-REM-AHI and sleep efficiency) recorded in the first half of the night and throughout the night was significant (p < 0.05) by both Pearson's correlation coefficient (r) and by the intraclass correlation coefficient (ICC). In 33 of 35 patients (94.3%) diagnostic agreement was achieved (95% CI 80.84-99.30); when SAHS was severe, agreement was 100%. Based on these results, we conclude that for patients with a diagnosis of severe SAHS during the first half of the night, data recorded during the second half can be considered supplementary.

Midline radiofrequency tissue reduction of the palate for bothersome snoring and sleep-disordered breathing: A clinical trial

This study is a prospective, nonrandomized clinical trial initiated to assess the safety and efficacy of radiofrequency tissue reduction of the palate for the treatment of bothersome snoring and sleep-disordered breathing. Twelve healthy volunteers with socially disruptive snoring underwent a baseline polysomnogram along with a battery of visual analog scales (VASs) to measure daytime sleepiness, snoring level, pain, and disturbances of speech and swallowing. After radiofrequency tissue reduction of the palate, they were re-evaluated with a mean follow-up after the final procedure of 15.7 +/- 5.1 (mean +/- SD) weeks. As rated by the bed partner, a significant reduction in the level of snoring occurred in all 12 patients, with a mean pretreatment snoring level of 8.3 +/- 2.1 to a mean posttreatment snoring level of 2.1 +/- 1.4. (Student t test, P < 0.0001) These patients required an average of 2.3 treatment sessions each. Nine of 12 had a reduction in snoring from a bothersome level (VAS range 5-10) to a nonbothersome level (VAS range 0-3). Daytime sleepiness as measured by the Epworth Sleepiness Scale (0-24) decreased from 10.8 +/- 4.4 to 8.3 +/- 4.1 (P = 0.011). Posttreatment pain was considered absent or minimal in 11 of 12 patients and was managed with acetaminophen. No significant adverse events or complications were reported.

Midline radiofrequency tissue reduction of the palate for bothersome snoring and sleep‐disordered breathing: A clinical trial

This study is a prospective, nonrandomized clinical trial initiated to assess the safety and efficacy of radiofrequency tissue reduction of the palate for the treatment of bothersome snoring and sleep-disordered breathing. Twelve healthy volunteers with socially disruptive snoring underwent a baseline polysomnogram along with a battery of visual analog scales (VASs) to measure daytime sleepiness, snoring level, pain, and disturbances of speech and swallowing. After radiofrequency tissue reduction of the palate, they were re-evaluated with a mean follow-up after the final procedure of 15.7 +/- 5.1 (mean +/- SD) weeks. As rated by the bed partner, a significant reduction in the level of snoring occurred in all 12 patients, with a mean pretreatment snoring level of 8.3 +/- 2.1 to a mean posttreatment snoring level of 2.1 +/- 1.4. (Student t test, P < 0.0001) These patients required an average of 2.3 treatment sessions each. Nine of 12 had a reduction in snoring from a bothersome level (VAS range 5-10) to a nonbothersome level (VAS range 0-3). Daytime sleepiness as measured by the Epworth Sleepiness Scale (0-24) decreased from 10.8 +/- 4.4 to 8.3 +/- 4.1 (P = 0.011). Posttreatment pain was considered absent or minimal in 11 of 12 patients and was managed with acetaminophen. No significant adverse events or complications were reported.

Visual P300 latency predicts treatment response to modafinil in patients with narcolepsy

To evaluate the hypothesis that visual P300 latency (VL) predicts treatment response to modafinil (a new wake-promoting agent) in patients with narcolepsy. Comparison of responders and non-responders in a double-blind randomized placebo-controlled trial. Private practice referral sleep disorders center. Twenty one patients with narcolepsy (ages 17-65 years). Auditory and visual P300 testing using 31 evenly spaced scalp electrodes, and baseline polysomnograms and objective and subjective tests of daytime sleepiness, followed by modafinil treatment for 9 weeks. Polysomnograms and tests of sleepiness were then repeated. The Maintenance of Wakefulness Test (MWT). Response defined as a final MWT > 7.3min (normative sample mean - 3 SD), plus an increase > 1SD based on normative sample (3.6 min) over baseline MWT. Non-responders had longer age-adjusted 31-electrode mean VL (448.4 ms vs. 410.8 ms, P = 0.024), and larger auditory P300 amplitude, with no topographical P300 differences. Non-responders and responders did not differ on any other baseline clinical variable. Using a cut-off of 0.5 SE from normal regression constant, shorter age-adjusted VL predicted modafinil response, with specificity of 0.71 and sensitivity of 0.86. VL predicts treatment response to modafinil in patients with narcolepsy.

Longer Auditory and Visual P300 Latencies in Patients with Narcolepsy

To compare auditory and visual P300 amplitude and latency magnitudes and topographies in patients with narcolepsy and normal subjects, 20 patients with polysomnographically-confirmed narcolepsy and 40 normal subjects were administered auditory and visual P300 testing using 31 evenly spaced scalp electrodes. Patients with narcolepsy were then administered baseline polysomnograms and objective (MSLT, Maintenance of Wakefulness Test or MWT) and subjective tests (Epworth Sleepiness Scale, Clinical Global Impression) of daytime sleepiness. Patients had longer 31-electrode mean age-adjusted auditory P300 latencies (406.0 +/- 27.8 vs. 385.7 +/- 28.9 ms, p = 0.012) and visual P300 latencies (427.3 +/- 29.0 vs. 411.4 +/- 27.7 ms., p = 0.044) than 40 normal subjects in the same age range. Age-adjusted auditory P300 latency was correlated with MWT (r = -0.49, p = 0.028), but not with any other clinical variable or measure of sleepiness. Age-adjusted visual P300 latency was not correlated with any clinical variable or measure of sleepiness. Patients with narcolepsy had longer auditory and visual P300 latencies than normal subjects.