Repeated nocturnal sleep latencies in narcoleptic, sleepy and alert subjects.

OBJECTIVES: The purpose of this study was to assess nocturnal sleep latencies among narcoleptics. METHODS: Thirteen narcoleptics and matched sleepy and alert controls participated in this study. Subjects were awakened three times on each of two experimental nights. The latencies to sleep and rapid eye movement sleep were evaluated at the beginning of the night and following each experimental awakening. RESULTS: The alert group (AG) had a significantly longer mean nocturnal sleep latency than the narcoleptic (NG) and sleepy groups (SG). The sleep latencies at 23:00 and 01:10 h were significantly longer than the latencies at 03:10 and 05:10 h. The interaction between group and time of night demonstrated longer latencies at 23:00 and 03:10 h for the AG when compared to the SG and the NG. At 01:10 and 05:10 h all groups had comparable latencies. The number of subjects in the NG who had multiple sleep onset REM periods (SOREMPs) was significantly higher than in either the AG or the SG. CONCLUSIONS: Narcoleptics were found to have a heightened propensity to fall asleep and increased number of SOREMPs during nocturnal sleep opportunities. These characteristics are consistent with the daytime polysomnographic findings known in this patient population.

The detection of brief daytime sleep episodes.

INTRODUCTION: In the present study we evaluated the characteristics of sleep-onset detection (during daytime nap opportunities) as a function of differing sleep lengths among healthy, asymptomatic subjects. METHODS: Twenty subjects were randomized into a Latin square design in which each subject received 1, 5, 10, and 20 minutes of sleep during an MSLT. Subjects were asked after each nap if they fell asleep. The rate of sleep detection was analyzed as a function of sleep duration. RESULTS: Three subjects detected sleep onset after 1 minute of sleep, 7 subjects after 5 minutes of sleep, 10 subjects after 10 minutes of sleep, and 14 after 20 minutes of sleep (chi 2 = 9.63, p < .05). CONCLUSIONS: The present data indicate the importance of sleep duration in an individual's ability to detect the occurrence of sleep. Importantly, only three subjects detected sleep after 1 minute of sleep, emphasizing the dangerous nature of brief sleep episodes in the context of public safety.

The perception of sleep as a function of the level of daytime sleepiness among patients with obstructive sleep apnea.

Subjective estimates of sleep onset among patients with a variety of sleep disorders have been shown to be inaccurate. This inability in perceiving sleep onset is potentially dangerous for this population, in particular, for individuals who are required to drive long distances or operate heavy machinery as part of their daily activities. This study evaluated the perception of sleep among 237 consecutive patients diagnosed with obstructive sleep apnea. Patients completed an overnight sleep-laboratory evaluation followed by an objective evaluation of sleep propensity. The latter was done using the Multiple Sleep Latency Test (MSLT). Patients with an accurate perception of having slept on the MSLT were found to have shorter sleep latencies when compared with those with an inaccurate perception of their sleep. The results of this study suggest that the rapidity with which sleep is manifested is an important contributor to the accurate perception of sleep.

Daytime CPAP titration: a viable alternative for patients with severe obstructive sleep apnea.

OBJECTIVE: Continuous positive airway pressure (CPAP) is the treatment of choice for patients diagnosed with severe obstructive sleep apnea (OSA). The implementation of CPAP therapy has traditionally been based on full-night titration studies or split-night protocols. This study compared a group of patients who received a regular nocturnal CPAP titration with patients who received a daytime CPAP titration. The objective of the study was to determine if daytime CPAP titration is a viable alternative for the implementation of CPAP treatment in patients with severe OSA. STUDY DESIGN: Fourteen patients (13 men and one woman) received a daytime CPAP titration (day group). The day group was matched to 18 patients (17 men and one woman) who were titrated under a full-night regular nocturnal study (night group). Eligible patients were those with severe OSA (respiratory event index > 40). The groups were matched by age, sex, and body mass index. RESULTS: Daytime and nocturnal CPAP titration studies yielded sufficient amounts of rapid eye movement (REM) and non-REM sleep to help determine CPAP settings. Importantly, the diurnal and nocturnal CPAP titrations resulted in comparable therapeutic pressures as well as comparable resolution of sleep-disordered breathing. After 1 week of treatment, the groups exhibited similar CPAP use and comparable improvements in subjective sleepiness as indicated by their increase in sleep/wake activity inventory scores. CONCLUSIONS: Daytime CPAP titration studies may be a viable alternative for the efficient and expedient implementation of CPAP therapy among some patients with severe OSA.

The sleep/wake habits of patients diagnosed as having obstructive sleep apnea.

STUDY OBJECTIVE: To determine the sleep/wake habits of patients diagnosed as having obstructive sleep apnea (ie, respiratory event index [REI] > or = 5). DESIGN: Case series with prospective data collection to determine the relationship among sleepiness, REI, and sleep/wake habits. Patients were grouped according to their multiple sleep latency test (MSLT) results (< or = 5 and > 5) and REI (mild REI < or = 20; moderate REI > 20 but < or = 60; and severe REI > 60). SETTING: An American Sleep Disorders Association-accredited sleep laboratory. PATIENTS: Three hundred ninety (325 male, 65 female) consecutive patients seen between June 1993 and January 1995 for evaluation of sleep apnea. This included a sleep, medical, and psychiatric evaluation followed by a physical examination. Sleep histories and sleep/wake habits were recorded by a physician trained in sleep medicine. Polysomnographic evaluation consisted of a nocturnal clinical polysomnogram (CPSG) and an MSLT on the following day. Of 390 patients, 268 completed polysomnographic evaluation (CPSG and MSLT). MEASUREMENTS AND RESULTS: Sleepy (MSLT < or = 5) patients with mild (REI < or = 20) and moderate apnea (REI > 20 < or = 60) reported spending significantly less time in bed than sleepy patients with severe apnea (REI > 60). Those with severe apnea (REI > 60) reported napping significantly more and experienced a more severe disruption of their routine daily activities because of sleepiness when compared with mild and moderate OSA patients. CONCLUSIONS: These data suggest that sleep habits have an important modulatory effect on the level of sleepiness and this effect is lost as the severity of sleep-disordered breathing increases.

The alerting effects of short and long naps in narcoleptic, sleep deprived, and alert individuals.

Eleven narcoleptic patients and 22 age- and gender-matched normal controls participated in a study to determine the alerting effects of differing nap lengths. All narcoleptic patients had been previously diagnosed [mean sleep latency on the multiple sleep latency test (MSLT) < or = 5 minutes with two or more sleep-onset rapid eye movement periods (SOREMPs)]. Healthy, normal subjects with a mean sleep latency on the screening MSLT > or = 8 minutes were randomly assigned to one of two groups (i.e. sleep-deprived and alert). All subjects completed two experimental night and days with at least 5 days between sessions. On the evening prior to each experimental day, narcoleptic and alert subjects spent 8 hours in bed and sleep-deprived subjects spent 0 hours in bed. The following day, all subjects underwent one of two napping conditions, 15 or 120 minutes in bed. Both naps were terminated at noon. Every subject underwent both conditions and the order of conditions was counterbalanced. From 1215 to 1355 hours all subjects underwent a modified MSLT. At 1500 hours, the subjects had a 1-hour nap. The results showed that the 120-minute nap condition was more beneficial than the 15-minute nap. Narcoleptic and sleep deprived subjects were shown to have comparable levels of sleepiness on the modified MSLT. However, a differential response pattern on their latency to sleep was noted on the 1-hour nap. Sleep-deprived subjects were shown to be differentially more alert following a 120-minute nap opportunity. In contrast, for narcoleptic patients the beneficial effects of the nap were lost when tested 3 hours later. These results show that narcoleptic patients benefit from a longer nap but that these benefits are short-lived.