Sodium oxybate in narcolepsy with cataplexy: Zurich sleep center experience.

Sodium oxybate (SO; Xyrem®) has been approved in most countries for treatment of narcolepsy and cataplexy. In this study, we present a single-center experience of a series of 18 patients with narcolepsy with cataplexy (18/18 DQB1*0602 positive, 17/17 with low/absent cerebrospinal fluid hypocretin) in whom SO was prescribed. After 26 ± 13 months, 13/18 patients were still on SO at a mean dosage of 6.1 ± 1.2 g (in 8 of them in combination with stimulants). The following significant effects were observed: improved subjective sleepiness (12/13), cataplexy (13/13; median number of attacks from 20 to 1/month), hallucinations (8/10) and sleep paralysis (8/8); increase in mean sleep latency on the Maintenance of Wakefulness Test (from 5.5 to 17.4 min) and sleep/rest efficiency on actigraphy (from 61 to 76%); decrease in Epworth Sleepiness Scale score (from 18 to 14), sleep onset REM periods on the Multiple Sleep Latency Test (from 3.6 to 2.4) and errors in the Steer-Clear Test (from 11 to 2%). Five patients discontinued SO because of insufficient compliance (n = 2), lack of efficiency (n = 1) and side effects (n = 1). These data confirm and expand previous reports on the good effects and tolerability of SO as a treatment for narcolepsy with cataplexy.

Modafinil ameliorates excessive daytime sleepiness after traumatic brain injury.

BACKGROUND: Excessive daytime sleepiness (EDS) and fatigue are common symptoms after traumatic brain injury (TBI), but there is no specific treatment for affected patients. With this pilot study, we aimed at studying the effect of daily modafinil on posttraumatic EDS and fatigue. METHODS: We conducted a prospective, double-blind, randomized, placebo-controlled pilot study in 20 patients with TBI who had fatigue or EDS or both. After baseline examinations (questionnaires including the Epworth Sleepiness Scale to assess EDS and the Fatigue Severity Scale to assess fatigue, actigraphy, polysomnography, maintenance of wakefulness test, and psychomotor vigilance test), 10 patients received 100 to 200 mg modafinil every morning, and 10 patients were treated with placebo. After a 6-week treatment period, all examinations were repeated. RESULTS: EDS improved significantly in patients with TBI who were treated with modafinil, compared with the placebo group. Similarly, the ability to stay awake on the maintenance of wakefulness test improved only in the modafinil group. Modafinil, however, had no impact on posttraumatic fatigue. Clinically relevant side effects were not observed. CONCLUSION: This study indicates that modafinil is effective and well tolerated in the treatment of posttraumatic EDS but not of fatigue. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that modafinil (100-200 mg daily) improves posttraumatic EDS compared with placebo. This study provides Class I evidence that modafinil (100-200 mg daily) does not improve posttraumatic fatigue compared with placebo.

Hypocretin (orexin) deficiency predicts severe objective excessive daytime sleepiness in narcolepsy with cataplexy.

Cerebrospinal fluid (CSF) hypocretin-1 deficiency is associated with definite ("clear cut") cataplexy in patients with narcolepsy. The relationship between CSF hypocretin-1 levels and other narcoleptic symptoms (including excessive daytime sleepiness, EDS) is not properly understood. In a consecutive series of 18 subjects with narcolepsy and definite cataplexy, patients with undetectable CSF hypocretin-1 (n = 12) were found to have significantly lower mean sleep latencies (p = 0.045) and a higher frequency of sleep onset REM periods (SOREMPs, p = 0.025) on multiple sleep latency test than patients (n = 6) with detectable levels. Conversely, Epworth sleepiness scale scores, the frequency of hallucinations/sleep paralysis, and the frequency and severity of cataplexy were similar in both groups. These results suggest that hypocretin deficiency identifies a homogenous group of patients with narcolepsy characterised by the presence of definite cataplexy, severe EDS, and frequent SOREMPs.

Electromagnetic fields, such as those from mobile phones, alter regional cerebral blood flow and sleep and waking EEG.

Usage of mobile phones is rapidly increasing, but there is limited data on the possible effects of electromagnetic field (EMF) exposure on brain physiology. We investigated the effect of EMF vs. sham control exposure on waking regional cerebral blood flow (rCBF) and on waking and sleep electroencephalogram (EEG) in humans. In Experiment 1, positron emission tomography (PET) scans were taken after unilateral head exposure to 30-min pulse-modulated 900 MHz electromagnetic field (pm-EMF). In Experiment 2, night-time sleep was polysomnographically recorded after EMF exposure. Pulse-modulated EMF exposure increased relative rCBF in the dorsolateral prefrontal cortex ipsilateral to exposure. Also, pm-EMF exposure enhanced EEG power in the alpha frequency range prior to sleep onset and in the spindle frequency range during stage 2 sleep. Exposure to EMF without pulse modulation did not enhance power in the waking or sleep EEG. We previously observed EMF effects on the sleep EEG (A. A. Borbély, R. Huber, T. Graf, B. Fuchs, E. Gallmann and P. Achermann. Neurosci. Lett., 1999, 275: 207-210; R. Huber, T. Graf, K. A. Cote, L. Wittmann, E. Gallmann, D. Matter, J. Schuderer, N. Kuster, A. A. Borbély, and P. Achermann. Neuroreport, 2000, 11: 3321-3325), but the basis for these effects was unknown. The present results show for the first time that (1) pm-EMF alters waking rCBF and (2) pulse modulation of EMF is necessary to induce waking and sleep EEG changes. Pulse-modulated EMF exposure may provide a new, non-invasive method for modifying brain function for experimental, diagnostic and therapeutic purposes.

Early morning melatonin administration impairs psychomotor vigilance.

The acute soporific effect of melatonin in humans has been demonstrated in a range of studies. How alertness and performance are changed after melatonin given in the morning is not yet known. In a double-blind, placebo-controlled study of nine healthy young men, melatonin was given at 0700 h under controlled conditions of a modified constant routine protocol lasting 56 h (2 days, 3 nights with sleep). A clear decrement in neurobehavioral functions as measured by the Psychomotor Vigilance Test lasted for 6 h after melatonin administration (particularly in the lapse domain and median of the reaction time) without any effect on a letter cancellation task. A subjective soporific effect was present but less pronounced. Thus, melatonin taken in the morning requires caution in situations where high attention is needed.

Functional link between distal vasodilation and sleep-onset latency?

Thermoregulatory processes have long been implicated in initiation of human sleep. The purpose of this study was to evaluate the role of heat loss in sleep initiation, under the controlled conditions of a constant-routine protocol modified to permit nocturnal sleep. Heat loss was indirectly measured by means of the distal-to-proximal skin temperature gradient (DPG). A stepwise regression analysis revealed that the DPG was the best predictor variable for sleep-onset latency (compared with core body temperature or its rate of change, heart rate, melatonin onset, and subjective sleepiness ratings). This study provides evidence that selective vasodilation of distal skin regions (and hence heat loss) promotes the rapid onset of sleep.

New tools for the generation of E1- and/or E3-substituted adenoviral vectors.

We have designed new vectors for the construction of recombinant adenoviruses containing expression cassettes in the E1 and/or E3 regions. Using a versatile set of restriction enzymes, the cassettes are cloned into small bacterial vectors and subsequently introduced into large plasmids containing the adenoviral sequences. Two positive selection markers facilitate the recovery of a cosmid containing a copy of the sequence of the recombinant adenovirus. The resulting cosmid is transfected into 293 or 911 cells in order to rescue the virus. Importantly, the method does not require any recombination event, either in E. coli or in mammalian cells. The entire procedure can generate viral plaques in 12 days. Gene Therapy (2000) 7, 80-87.

Haloperidol disrupts, clozapine reinstates the circadian rest-activity cycle in a patient with early-onset Alzheimer disease.

Measurement of the circadian rest-activity cycle in a patient with early-onset Alzheimer disease for 555 days revealed marked changes in the timing and amount of nocturnal activity. After neuroleptic medication was changed to haloperidol, the rest-activity cycle became completely arrhythmic for two months, concomitant with a marked worsening of cognitive state. Circadian integrity returned together with clinical improvement when the patient was subsequently treated with clozapine. This observation suggests that the known tendency for patients with Alzheimer disease to develop sleep-wake cycle disturbances may be aggravated by a classic neuroleptic; in contrast, the atypical neuroleptic clozapine may consolidate it. Similar observations in schizophrenic patients indicate that this chronobiological finding is drug- and not illness-related.

A rapid-cycling bipolar patient treated with long nights, bedrest, and light.

BACKGROUND: Stabilization of rapid-cycling bipolar disorder is extremely difficult. METHODS: A refractory bipolar I rapid-cycling patient on valproate was treated with long "nights" (extended sleep in darkness) and daytime light therapy. RESULTS: Rapid cycling immediately stopped on initiation of a 10 hour dark/rest period. This was extended to 14 hours (plus a self-selected 1 hour midday nap) without problems. Depression gradually improved when midday light therapy was added; near-euthymia was attained after light therapy was shifted to the morning. CONCLUSIONS: Nonpharmacological chronobiological treatments may be a means to interrupt rapid cycling.

Effect of frequent brief awakenings from nonREM sleep on the nonREM-REM sleep cycle.

In the framework of a selective sleep deprivation study, eight young men were repeatedly awakened during 3 nights from nonREM sleep (nonREMS). The mean number of awakenings per night was 27.4, 29.5 and 32.8. In order to avoid excessive suppression of slow wave sleep, no awakening occurred in the first nonREMS episode. Compared to baseline, cycle 2 was significantly prolonged in all 3 nights, and cycle 3 in night 3 only. However, after subtracting the waking intervals, the differences from baseline was eliminated. The results show that the mechanisms underlying sleep cycle control keep track of sleep time and disregard epochs of waking.

Selective REM sleep deprivation in humans: effects on sleep and sleep EEG.

To investigate rapid eye movement (REM) sleep regulation, eight healthy young men were deprived of REM sleep for three consecutive nights. In a three-night control sleep deprivation (CD) session 2 wk later, the subjects were repeatedly awakened from non-REM sleep in an attempt to match the awakenings during the REM sleep deprivation (RD) nights. During the RD nights the number of sleep interruptions required to prevent REM sleep increased within and across consecutive nights. REM sleep was reduced to 9.2% of baseline (CD nights: 80.7%) and rose to 140.1% in the first recovery night. RD gave rise to changes in the EEG power spectra of REM sleep. Power in the 8.25- to 11-Hz range was reduced in the first recovery night, an effect that gradually subsided but was still present in the third recovery night. The rising REM sleep propensity, as reflected by the increase of interventions within and across RD nights, and the moderate REM sleep rebound during recovery can be accounted for by a compensatory response that serves REM sleep homeostasis. The changes in the electroencephalogram power spectra, which were observed during enhanced REM sleep propensity, may be a sign of an altered quality of REM sleep.

Spindle frequency activity in the sleep EEG: individual differences and topographic distribution.

The brain topography of EEG power spectra in the frequency range of sleep spindles was investigated in 34 sleep recordings from 20 healthy young men. Referential (F3-A2, C3-A2, P3-A2 and O1-A2) and bipolar derivations (F3-C3, C3-P3 and P3-O1) along the anteroposterior axis were used. Sleep spindles gave rise to a distinct peak in the EEG power spectrum. The distribution of the peak frequencies pooled over subjects and derivations showed a bimodal pattern with modes at 11.5 and 13.0 Hz, and a trough at 12.25 Hz. The large inter-subject variation in peak frequency (range: 1.25 Hz) contrasted with the small intra-subject variation between derivations, non-REM sleep episodes and different nights. In some individuals and/or some derivations, only a single spindle peak was present. The topographic distributions from referential and bipolar recordings showed differences. The power showed a declining trend over consecutive non-REM sleep episodes in the low range of spindle frequency activity and a rising trend in the high range. The functional and topographic heterogeneity of sleep spindles in conjunction with the intra-subject stability of their frequency are important characteristics for the analysis of sleep regulation on the basis of the EEG.

Fronto-occipital EEG power gradients in human sleep.

The brain topography of power spectra along the antero-posterior (A-P) axis was studied in the all-night human sleep EEG. Spectra (0.25 - 25.0 Hz) were computed for an anterior (A; F3-C3), a middle (M; C3-P3) and a posterior (P; P3-O1) bipolar derivation, and the spectral gradients between two adjacent derivations were expressed by power ratios (A/M and M/P). At NREM-REM sleep transitions a power shift from A to M was present over almost the entire frequency range, while the direction of shifts between M and P differed between frequency bands. Within NREM sleep, frequency specific power gradients were present: In the low delta band power in both A (0.25 Hz bin) and P (0.25-1.0 Hz bins) was higher than in M. In the 4-9 Hz range the relation was A > M > P, and in the 15 - 25 Hz range power was largest in M. Power in the spindle frequency range was highest at 11.75 Hz in M, and at 13.5 - 13.75 Hz in A. Topographical differences were seen also in the temporal changes of power across and within NREM sleep episodes. Whereas NREM sleep power in the 2-Hz bin was higher in A than in M in the first episode, this difference vanished in the course of the night. This result points to a specific involvement of frontal parts of the cortex in sleep homeostasis. The regional differences in sleep EEG spectra indicate that sleep is not only a global phenomenon but also a local brain process with a different regional involvement of neuronal populations.

Brain topography of the human sleep EEG: antero-posterior shifts of spectral power.

To investigate the brain topography of the human sleep EEG along the antero-posterior axis, spectra (0.25-25 Hz; 1 Hz bins) were computed from all-night EEG recordings (n = 20 subjects) obtained from an anterior F3-C3) and a posterior (P3-O1) derivation. State-dependent and frequency-dependent topographic differences were observed. In non-rapid eye movement (REM) sleep, power in the anterior derivation was higher than in the posterior derivation in the 2 Hz bin, and lower in the 4-10 Hz bins. In REM sleep, a posterior dominance was present in most bins below 18 Hz. The 2-6 Hz bins exhibited an antero-posterior shift of power over consecutive non-REM sleep episodes. Consistent shifts of power were also present within non-REM sleep episodes. The results suggest that anterior and posterior cortical regions may be differently involved in the sleep process.

Dynamics of the sleep EEG after an early evening nap: experimental data and simulations.

Increasing sleep pressure is associated with highly predictable changes in the dynamics of the sleep electroencephalogram (EEG). To investigate whether the effects of reduced sleep pressure also can be accounted for by homeostatic mechanisms, nighttime sleep following an evening nap was recorded in healthy young men. In comparison with the baseline night, sleep latency in the postnap night was prolonged, rapid eye movement sleep (REMS) latency was reduced, and EEG power density in non-REMS was decreased in the delta and theta band. The buildup of both EEG slow-wave activity (SWA; power density in the 0.75-to 4.5-Hz range) and spindle frequency activity (SFA; power density in the 12.25-to 15.0-Hz range) in non-REMS episodes was diminished (SWA: episodes 1-3; SFA: episode 1). The typical declining trend of SWA over consecutive non-REM sleep episodes was attenuated. The time course of SWA could be closely simulated with a homeostatic model of sleep regulation, although some discrepancies in level and buildup of SWA were apparent. We conclude that homeostatic mechanisms can largely account for the dynamics of the sleep EEG under conditions of reduced sleep pressure.

Sleep and the sleep electroencephalogram across the menstrual cycle in young healthy women.

Cyclic changes in hormones, body temperature, and metabolic rate characterize the menstrual cycle. To investigate whether these changes are associated with changes in sleep and the sleep electroencephalogram (EEG), a total of 138 sleep episodes from 9 women with no premenstrual syndrome symptoms were recorded every second night throughout one ovulatory menstrual cycle and analyzed in relation to menstrual phase. Ovulation and menstrual cycle stage were confirmed by measurements of temperature, urinary LH, and midluteal plasma levels of estrogen and progesterone. No significant variation across the menstrual cycle was observed for subjective ratings of sleep quality and mood as well as for objective measures of total sleep time, sleep efficiency, sleep latency, rapid eye movement sleep latency, and slow wave sleep. In nonrapid eye movement sleep, EEG power density in the 14.25-15.0 hertz band, which corresponds to the upper frequency range of the sleep spindles, exhibited a large variation across the menstrual cycle, with a maximum in the luteal phase. The data show that in healthy young women, sleep spindle frequency activity varies in parallel with core body temperature, whereas homeostatic sleep regulatory mechanisms, as indexed by the time course of EEG slow wave activity are not substantially affected by the menstrual cycle.

Melatonin effect on daytime sleep in men: suppression of EEG low frequency activity and enhancement of spindle frequency activity.

The effect of melatonin (5 mg, p.o.) on electroencephalographic (EEG) activity during sleep was investigated in eight men in a placebo-controlled cross-over design. Melatonin was administered immediately prior to a 4-h daytime sleep episode (13-17 h) after a partial sleep deprivation. The non-REM sleep stages and REM sleep duration were not significantly affected. Melatonin enhanced EEG power density in non-REM sleep in the 13.75-14.0 Hz bin (i.e., within the frequency range of sleep spindles), and reduced activity in the 15.25-16.5 Hz band. In the first 2 h spectral values within the 2.25-5.0 Hz range were reduced. These changes in the EEG are to some extent similar to those induced by benzodiazepine hypnotics and to the contribution of the endogenous circadian pacemaker to the spectral composition of the sleep EEG when sleep occurs at night.

Time course of sleep inertia after nighttime and daytime sleep episodes.

Sleep inertia refers to the period of reduced vigilance following upon awakening from sleep. To investigate the time course of sleep inertia, self-ratings of alertness and reaction time in a memory task were repeatedly assessed after nighttime and daytime sleep episodes in healthy young men. Alertness gradually increased and reaction time gradually decreased within the first hour after awakening. Their time course could be described by exponential functions with time constants of 0.45 h and 0.3 h, respectively. The data demonstrate that sleep inertia is a robust, quantifiable process that can be incorporated in models of sleep and vigilance.