Forty-eight-hour polysomnographic evaluation of narcolepsy.

Eleven narcoleptic and 11 control subjects completed five multiple sleep latency test (MSLT) procedures with instructions to "fall asleep" while supine and five maintenance of wakefulness test (MWT) procedures with instructions to "remain awake" while comfortably sitting. Narcoleptic subjects had a shorter sleep latency and a higher frequency of sleep onset REM periods (SOREMPs) on both daytime tests than controls. Each group had a longer sleep latency on the MWT than MSLT. For patients with narcolepsy, the differences between the two daytime procedures suggest the tests measure distinct aspects of sleep-wake tendency. Sleep latency on the MSLT did not correlate with sleep latency on the MWT for narcoleptic subjects. Furthermore, the number of SOREMPs during the MSLT for narcoleptic subjects did not correlate with the number of SOREMP during the MWT. Measures of nocturnal REM sleep for narcoleptic subjects correlated with sleep latency on the MSLT. In particular, REM latency at night was highly predictive of the magnitude of hypersomnia for patients with narcolepsy. Sleep latency at night tended to relate to sleep latency on the daytime tests for controls. Patients with narcolepsy had a shorter sleep latency, more frequent arousals, and a shorter REM latency than control subjects across the 2 nights of study.

Tobacco use by narcoleptics and daytime sleep tendency.

The nocturnal sleep and daytime sleep tendency were assessed in 10 narcoleptics who regularly smoked cigarettes and 10 narcoleptics who did not use tobacco. Standard sleep-wake polygraphic measures were recorded during the 24-h study. There were no statistical differences between groups in terms of nighttime sleep structure, although tobacco use resulted in a decreased sleep duration. Smokers tended to fall asleep more rapidly than non-smokers throughout daytime multiple sleep latency testing. The data failed to demonstrate a daytime arousal effect of tobacco for patients with narcolepsy.

Obstructive sleep apnea and body weight.

A patient with obstructive sleep apnea was monitored five times during three years while his weight fluctuated within a range of 26 kg. The number of apneas per hour of sleep varied from 59.6 at 111 kg of weight to 3.1 at 85 kg. The relation between apneas per hour of sleep and body weight was a logarithmic function. A modest decrease in weight was thus associated with a disproportionally larger decrease in the rate of apneas. Typical SaO2 levels during the apneic episodes also had a logarithmic relation with body weight. Apnea-related sinus bradycardia and sinus tachycardia were only present at the highest weight. The results suggested that dieting and weight loss lead to an improvement in sleep apnea and related sequelae.

REM sleep episodes during the maintenance of wakefulness test in patients with sleep apnea syndrome and patients with narcolepsy.

Twelve patients with sleep apnea, 12 narcoleptic patients, and 10 controls were given 20-min opportunities to remain awake while sitting comfortably. Test sessions were administered at 10:00, 12:00, 14:00, 16:00, and 18:00. Apneic and narcoleptic subjects were less capable of maintaining wakefulness than controls. Patients with sleep apnea had an average of 1.4 daytime rapid eye movement (REM) episodes with the peak incidence at 14:00. Narcoleptics also had sleep onset REM periods (mean of 2.7), whereas none of the controls had REM episodes during the daytime testing. Narcoleptic and control groups differed in the probability of REM occurring at each session. There were time-of-day differences in the probability of REM occurring between patient groups. The amount of stage REM the night preceding testing was unrelated to the occurrence of REM episodes during the day in either patient group. In addition, there were notable differences in the frequency of sleep onset REM periods when patients were sitting as opposed to being supine during nap studies. Sleep latency and frequency of REM episodes on the maintenance of wakefulness test were independent of the subject's age. The maintenance of wakefulness test proved unsatisfactory as a diagnostic procedure, but appeared useful as an adjunct procedure in the evaluation of treatment efficacy of hypersomnia.

Maintenance of wakefulness test: a polysomnographic technique for evaluation treatment efficacy in patients with excessive somnolence.

Ten patients with narcolepsy were given five 20 min opportunities to remain awake throughout the day. Trials were offered at 2 h intervals beginning at 10:00. Polysomnographic variables were monitored during each trial. Sleep latency increased when patients were instructed to maintain wakefulness compared to when instructed to sleep; however, sleep latencies were still lower for narcoleptics than for control subjects. Unexpectedly, we were not always able to document patients' reports of increased ability to stay awake. The findings suggested that clinical data on symptom control in narcolepsy do not predict ability to stay awake. Objective measures of the ability are potentially more useful in evaluating treatment.