Sleep bruxism and sleep arousal: an experimental challenge to assess the role of cyclic alternating pattern.

Rhythmic masticatory muscle activity (RMMA) is the characteristic electromyographic pattern of sleep bruxism (SB), a sleep-related motor disorder associated with sleep arousal. Sleep arousals are generally organised in a clustered mode known as the cyclic alternating pattern (CAP). CAP is the expression of sleep instability between sleep maintaining processes (phase A1) and stronger arousal processes (phases A2 and A3). This study aimed to investigate the role of sleep instability on RMMA/SB occurrence by analysing CAP and electroencephalographic (EEG) activities. The analysis was performed on the sleep recordings of 8 SB subjects and 8 controls who received sensory stimulations during sleep. Baseline and experimental nights were compared for sleep variables, CAP, and EEG spectral analyses using repeated measure ANOVAs. Overall, no differences in sleep variables and EEG spectra were found between SB subjects and controls. However, SB subjects had higher sleep instability (more phase A3) than controls (P= 0·05). The frequency of phase A3 was higher in the pre-REM sleep periods (P < 0·001), where peaks in RMMA/SB activity were also observed (P = 0·05). When sleep instability was experimentally increased by sensory stimuli, both groups showed an enhancement in EEG theta and alpha power (P = 0·04 and 0·02, respectively) and significant increases in sleep arousal and all CAP variables. No change in RMMA/SB index was found within either groups (RMMA/SB occurred in all SB subjects and only one control during the experimental night). These findings suggest that CAP phase A3 may act as a permissive window rather than a generator of RMMA/SB activity in predisposed individuals.

Evaluation of milk enzymes and electrolytes, plasma metabolites, and oxidative status in twin cows milked in an automatic milking system or twice daily in a conventional milking parlor.

The aim of this paper was to evaluate the effects of automatic milking (AM) on milk enzymes and minerals related to mammary epithelial integrity in comparison with twice-daily conventional milking (CM). One cow from each of 6 pairs of twins was assigned to be milked with AM or with CM throughout first lactation. Milk production was recorded and milk samples were collected at 4, 11, 18, 25, 32, and 39 wk of lactation (WOL) to determine fat and protein content, somatic cell count, pH, plasminogen (pl) and plasmin (Pl) activities, Na, K, and Cl. Body condition score was monitored; blood samples were collected to determine energy-related metabolites in the first third of lactation (14 WOL), and plasma oxidative status throughout lactation. Overall mean and standard deviation of milking frequency (MF) in AM were 2.69 and 0.88, respectively. Milk production, fat and protein contents, and somatic cell count did not differ between milking systems. The pl and pl+Pl activities were lesser in AM than in CM. Milk pH was greater in AM than in CM. Milk Na, K, Na/K ratio, and Cl did not differ across the whole lactation. Milk pH had a positive correlation with milk Pl activity (r = 0.41), Na (r = 0.37), and Cl (r = 0.40) concentration, and negative correlation with the log(10) of pl/Pl ratio (r = -0.47). The milk Na/K ratio had a positive correlation (r = 0.55) with milk Pl activity. Milking system (MS) did not seem to affect mammary epithelial permeability. The differences in enzymatic (proteolytic) activity due to the MS, probably related to daily MF, lead one to suppose that the quality of the protein fraction for the cheese-making process was preserved better with AM than with CM, even if differences in pH might negatively interfere. No difference was detected in BCS, and in plasma concentration of triglycerides and nonesterified fatty acids, whereas plasma cholesterol concentration during the first 10 WOL was lesser in AM than CM. Oxidative status, measured by plasma reactive oxygen metabolites and thiol groups, did not differ between MS throughout the whole lactation. These results suggest that early lactation of AM primiparous cows may give rise to crucial situations: for milk production, when a low MF may impair further mammary cell proliferation; for milk quality, if an irregular MF, with prolonged milking intervals, leads to an increased milk pH with increased conversion of pl to Pl.

The effects of subterranean clover phytoestrogens on sheep growth, reproduction and carcass characteristics.

The aim of the present study was to evaluate the effect of a prolonged administration of phytoestrogens on sheep growth rate, female reproductive response, lamb carcass conformation and meat quality. To investigate these effects, two groups of Comisana sheep (24 females and 20 males, initial average live weights of 25.0 and 29.9kg, respectively) were fed on subterranean clover (SC, phytoestrogen content=0.8mg/g of DM) and Italian ryegrass (C, non-oestrogenic control diet) for about one year. Feedstuffs were offered ad libitum and supplemented with maize grain and sunflower meal to maintain an adequate and similar energy and protein intake. The results demonstrated that the prolonged administration of the selected subterranean clover cultivars, with low formononetin content (lower than 10% of total isoflavones on dry basis), did not affect ewe reproduction but induced a significant improvement in animal weigh gain and, in males, good carcass and meat characteristics.

The effect of amantadine on arousal and EEG patterns in Creutzfeldt-Jakob disease.

In recent years, Creutzfeldt-Jakob disease (CJD) has been supposed to be of viral origin, and amantadine hydrochloride has been suggested as therapy because of its proved antiviral action. We studied nine patients with CJD (confirmed at autopsy in seven). Four were treated with amantadine hydrochloride, in dosages ranging from 3.5 to 15 mg/kg/day for an average period of 32 days. The clinical evolution of their disease was compared with that in five patients receiving only supportive maintenance therapy. The length of survival from the onset of clinical care did not differ significantly between the two groups. Nevertheless, a transient improvement in wakefulness and mentation was observed in three patients treated with amantadine, and EEG changes were observed in two, consisting above all of a reduction in the slow-wave activity and the periodic discharges (PDs). Amantadine administered intravenously did not induce any short-term changes in the PDs or the cyclic alternating pattern.

Seizures triggered by blinking when beginning to speak.

A patient had seizures triggered by spontaneous blinking associated with the act of beginning to speak. Diffuse paroxysmal discharges in the EEG appeared when the patient was blinking in darkness or in bright light. Closing the eyes voluntarily, on command, or as a reflex reaction produced this response very infrequently. During intermittent photic stimulation the epileptic discharges were accompanied by myoclonic jerks. The act of beginning to speak was linked with spontaneous blinking and EEG changes and was accompanied consistently by seizures. These were characterized by a peculiar stuttering and an absencelike impairment of consciousness. Seizures have been controlled well using clonazepam and valproic acid.

Sleep reactivity during acute nasal CPAP in obstructive sleep apnea syndrome.

OBJECTIVE: To measure the readjustments of sleep macro- and microstructure in patients with obstructive sleep apnea syndrome (OSAS) after acute nasal continuous positive airway pressure (NCPAP) treatment. BACKGROUND: The conventional polysomnographic analysis (macrostructure of sleep) does not necessarily provide the best measures of sleep disruption associated with OSAS. In contrast, microstructural methods of analyzing sleep (i.e., arousals and cyclic alternating pattern) may improve evaluation of patients with OSAS. METHOD: - Ten patients with OSAS were monitored polygraphically before and during the first night of NCPAP therapy. The results were compared with those of 10 age- and sex-matched controls without sleep-related breathing disorders. Each nocturnal recording was followed by daytime observation using the multiple sleep latency test and Visual Analogue Scale (VAS). RESULTS: The first night of ventilatory therapy was characterized by a remarkable expansion of stages 3 and 4 and of REM sleep. In addition, NCPAP suppressed the presence of cyclic alternating pattern (CAP) in REM sleep and induced an impressive rebound of arousals and of certain CAP variables-i.e., CAP rate, CAP time, number of CAP cycles-which dropped well below the physiologic values expressed by controls. A normal duration of phases A and B was re-established starting the first treatment night. When we matched sleep variables with the indices of daytime function, a significant correlation emerged only between the variations of CAP rate and VAS scores. In particular, improvement of daytime sleepiness was less evident when the ventilatory-induced drop of CAP rate was more pronounced. CONCLUSIONS: The application of CAP variables to the microstructural analysis of sleep may expand our knowledge regarding sleep and respiration.

Charcot-Marie-Tooth disease type 2 with restless legs syndrome.

In a series of 44 consecutive patients with Charcot-Marie-Tooth disease (CMT), we found restless legs syndrome (RLS) in 10 of 27 CMT type 2 (CMT2) patients (37%) and in none of 17 CMT type 1 patients (p = 0.004). In the CMT2 patients, RLS was associated with positive sensory symptoms (10/10 versus 10/17; p = 0.026). This finding supports the view that a disorder of sensory input plays a role in the pathogenesis of RLS. Symptomatic treatment may benefit these patients.

Evaluation of EEG cyclic alternating pattern during sleep in insomniacs and controls under placebo and acute treatment with zolpidem.

In nonrapid eye movement (NREM) sleep, electroencephalographic cyclic alternating patterns (CAPS) express the organized complexity of arousal-related phasic events. As a translation of sustained instability of the arousal level, CAPS increase under perturbation and decrease under sleep-promoting conditions. After adaptation to the sleep lab, 18 subjects (12 with persistent psychophysiological insomnia and 6 without sleep complaints), all aged 40-60 years, underwent a random sequence of two nonconsecutive nocturnal recordings, one under placebo and one under an imidazopyridine hypnotic agent (zolpidem). The choice of this drug was oriented by its capability to warrant, at the selected dose of 10 mg, a physiological profile of sleep. Polysomnographic parameters and self-report of sleep quality by means of visual analogue scale (VAS) were assessed by analysis of variance followed by a Scheffé test when F statistics were significant. The placebo nights of controls showed a significantly longer duration of total sleep time (+60 minutes) compared with the placebo nights of insomniacs. However, no relevant differences emerged from the other traditional polysomnographic variables. Conversely, CAP rate (CAP time x 100/NREM sleep time) showed highly sensitive and consistent modifications. Under placebo, CAP rate was significantly higher among insomniacs compared with controls (62.2% vs. 38.5%). Under medication, CAP rate dropped to 26.8% in insomniacs, whereas it was only moderately reduced in controls (31%). CAP rate values paralleled the self-rating estimation of sleep quality, but the VAS means differed significantly only among insomniacs where a sharp average fall from 45 mm (placebo nights) to 15 mm (zolpidem nights) could be detected. Our findings suggest that CAP rate in sleep analysis can represent a useful tool for the diagnosis of insomnia and for gaining insight into the therapeutic efficacy of hypnotic-sedative drugs.

Relationship of slow and rapid EEG components of CAP to ASDA arousals in normal sleep.

STUDY OBJECTIVES: Besides arousals (according to the ASDA definition), sleep contains also K-complexes and delta bursts which, in spite of their sleep-like features, are endowed with activating effects on autonomic functions. The link between phasic delta activities and enhancement of vegetative functions indicates the possibility of physiological activation without sleep disruption (i.e., arousal without awakening). A functional connection seems to include slow (K-complexes and delta bursts) and rapid (arousals) EEG events within the comprehensive term of activating complexes. CAP (cyclic alternating pattern) is the spontaneous EEG rhythm that ties both slow and rapid activating complexes together during NREM sleep. The present study aims at exploring the relationship between arousals and CAP components in a selected sample of healthy sleepers. DESIGN: Polysomnographic analysis according to the scoring rules for sleep stages and arousals. CAP analysis included also tabulation of subtypes A1 (slow EEG activating complexes), A2 and A3 (activating complexes with fast EEG components). SETTING: 40 sleep-lab accomplished recordings. PARTICIPANTS: Healthy subjects belonging to a wide age range (38 +/- 20 yrs.). INTERVENTIONS: N/A. MEASUREMENT AND RESULTS: Of all the arousals occurring in NREM sleep, 87% were inserted within CAP. Subtypes A2 and A3 of CAP corresponded strikingly with arousals (r=0.843; p<0.0001), while no statistical relationship emerged when arousals were matched with subtypes A1 of CAP. Subtypes A1 instead correlated positively with the percentages of deep sleep (r=0.366; p<0.02). CONCLUSIONS: The CAP subtype classification encompasses both the process of sleep maintenance (subtypes A1) and sleep fragmentation (subtypes A2 and A3), and provides a periodicity dimension to the activating events of NREM sleep.

Effect of age on EEG arousals in normal sleep.

EEG arousals were quantified in 40 nocturnal polysomnographic recordings belonging to four age groups (teenagers: 10 to 19 years; young adults: 20 to 39 years; middle-aged: 40 to 59 years; elderly: > or = 60 years). Ten subjects (five males and five females) participated in each group. The subjects were healthy and sound sleepers. All sleep recordings were preceded by an adaptation night which aimed at excluding the presence of sleep-related disorders. The recordings were carried out in a partially soundproof recording chamber and in a standard laboratory setting. Arousal indices (AI), defined as the number of arousals per hour of sleep, were calculated for total sleep time (AI/TST) and for all the sleep stages. AI/TST increased linearly with age (r = 0.852; p < 0.00001): teenagers (13.8), young adults (14.7), middle-aged (17.8), elderly (27.1). An age-related positive linear correlation was found also for the arousal indices referred to NREM sleep (r = 0.811; p < 0.00001) and to stages 1 and 2 (r = 0.712; p < 0.00001), while in stages 3 and 4 and in REM sleep, arousal indices showed stable values across the ages. Overall, arousals lasted 14.9 +/- 2.3 seconds, with arousal duration stable across the ages (range of means: 13.3-16.6 seconds) and no relevant differences between NREM sleep (14.6 +/- 2.5 seconds) and REM sleep (16.2 +/- 5 seconds). The paper discusses the impact of age on arousals, the similarities between arousals and the phases d'activation transitoire, and the consideration that arousals are physiological components of sleep.

The cyclic alternating pattern as a physiologic component of normal NREM sleep.

The cyclic alternating pattern (CAP) is a long-lasting periodic activity consisting of two alternate electroencephalogram (EEG) patterns. This variation in EEG is closely related to fluctuations in the level of arousal that characterize two different functional states in the arousal control mechanism. We studied 20 sleep records of 10 healthy subjects to see if CAP appears under physiologic conditions. During NREM sleep, CAP corresponded to a periodic succession of spontaneous phasic phenomena recurring within every stage, i.e., intermittent alpha rhythm, K-complex sequences, and reactive slow wave sequences. The following analyses were performed. Each EEG specific alternating pattern, defined as a cycle, was subdivided into two phases depending on the arousal response to stimulation. Average cycle length, average duration of each phase, and average ratio phase/cycle were calculated. CAP rate defined as (CAP time/Sleep time) was calculated for total sleep time (TST), (Cap time/TST); for NREM sleep, (CAP time/Total NREM); and for each NREM sleep stage. CAP is the EEG translation of the reorganization of the sleeping brain challenged by the modification of environmental conditions.

Nocturnal eating syndrome in adults.

Ten adult subjects were referred to our sleep disorders center complaining of difficulty in maintaining sleep due to frequent and recurrent awakenings to eat or drink. All patients manifested more than one episode per night, characterized by compulsive food seeking and a return to sleep only after adequate food intake. Food-seeking drive was described as an urgent abnormal need to swallow food and was associated with an absence of real hunger. Six subjects showed an elective nighttime intake of carbohydrates, and in all cases only edible substances were injected. The patients were always fully awake during the episodes and could clearly recall them in the morning. Polysomnographic investigation showed low levels of sleep efficiency, a high number of awakenings and a strict relation between nocturnal eating episodes and nonrapid eye movement (NREM) sleep. The average length of each episode was 3.5 minutes. The "eating latency", that is the interval between awakening and chewing start, was shorter than 30 seconds in 50% of the episodes. No medical, hormonal or neurological disorders were found during clinical and laboratory investigations. Body mass index was abnormally high in six patients. Anorexia nervosa and bulimia were carefully excluded. Various psychiatric disturbances were found in nine subjects, who were nevertheless well-functioning adults. Concurrent dyssomniac disorders, such as narcolepsy or periodic leg movements occasionally associated with restless legs syndrome, were diagnosed in five patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Precocious loss of physiological sleep in a case of Creutzfeldt Jakob disease: a serial polygraphic study.

Creutzfeldt-Jakob disease (CJD) is a prion-related subacute encephalopathy producing widespread neuronal degeneration and spongiform pathological changes, especially in the neocortex. Progressive dementia, motor signs and electroencephalographic (EEG) alterations characterize the full stage of the disease. A series of eight 24-hour polygraphic recordings were carried out in the last 3 months of life of a 68-year-old female patient affected by CJD that was confirmed neuropathologically. Genetic classification demonstrated this patient to have a sporadic form of the disease. The polygraphic recordings demonstrated three types of EEG findings, as follows: 1) sustained pseudoperiodic discharges (SPD), characterized by long-lasting diffuse sequences of slow sharp waves or di- or triphasic slow waves recurring at 0.5- to 1.5-second intervals; 2) discontinuous pseudoperiodic discharges (DPD), consisting of runs of pseudoperiodic discharges (PD)(phase A) cyclically replaced at about 1-minute intervals with semi-rhythmic theta-delta activities (phase B); 3) non-rapid eye movement (NREM) sleep-like pattern, with dominant 0.5- to 4-Hz activities, less rhythmic than the EEG of phase B. Only these three EEG patterns occurred spontaneously during the repeated polygraphic sessions. The NREM sleep-like pattern was found only in the first recording, whereas the following polygraphic sessions were occupied exclusively by SPD or by a DPD pattern. SPD was associated with either a relatively high level of vigilance (along the first three recordings) or a state of alert-appearing silent immobility (following the fourth recording). During DPD, the patient was unable to accomplish any voluntary movement and fluctuated between levels of greater arousal (phase A) and lesser arousal (phase B). Just as in stage 2 coma, the fluctuations between phases A and B of DPD were synchronous with phasic modifications of muscle activity and neurovegetative functions. In particular, reinforcement of muscle tone and myoclonic spasms coincided with phase A, whereas heart rate deceleration and respiratory pauses or decrease in flow were synchronous with phase B. As EEG evolved toward the disappearance of DPD and finally to flatness, the phase-locked coordination among arousal, somatic and vegetative activities was progressively impaired and was replaced with an uncontrolled exaggeration of cardiorespiratory activity. The genetic, neuropathological and polysomnographic differences between CJD and another prion disease, fatal familial insomnia, are discussed.

Polysomnographic effects of hypnotic drugs. A review.

This review aims at providing a critical assessment of the effects of the most widely used benzodiazepine (flurazepam, flunitrazepam, temazepam, triazolam) and non-benzodiazepine (zopiclone and zolpidem) hypnotic drugs, based on the recording of polysomnographic variables. In the light of newly acquired neurophysiological data on the microstructure of sleep, this paper reconsiders the problem of insomnia and the current ideas on polysomnography and hypnotic drugs.

Clinical and polysomnographic effects of trazodone CR in chronic insomnia associated with dysthymia.

Six middle aged subjects complaining of chronic insomnia associated with dysthymia were investigated in a 2-month single blind study: a 7-day placebo treatment period, followed by a 6-week phase with increasing doses of trazodone controlled release (CR) formulation (50 mg through days 8-10; 75 mg through days 11-13; 150 mg through days 14-49) and then a final 7-day withdrawal period under placebo. Medication was always administered at bedtime. Five polysomnographic recordings were accomplished by each subject (sleep 1: under baseline placebo; sleep 2-3-4; under active treatment; sleep 5: after drug discontinuation). A "blind" EEG reader analysed the traditional polysomnographic variables (macrostructure of sleep) and the amount and percentage ratio (CAP rate) of cyclic alternating pattern (CAP), the microstructural parameter that measures the instability of arousal during sleep. Visual analogue scales (VAS) for the evaluation of subjective sleep quality and the Hamilton rating scale for depression (HAM-D) were regularly assessed across the study. Statistical analysis was based on an ANOVA test with repeated measures completed by means of Bonferroni adjusted probabilities. No significant differences emerged from the macrostructural parameters referred to sleep initiation and maintenance, while significant overall modifications emerged from stage 2 (P < 0.0005), slow wave sleep (P < 0.0001), total CAP time (P < 0.0001) and CAP rate (P < 0.0001). Compared to the placebo baseline night, a significant increase of slow wave sleep (+40 min) and significant reductions of stage 2 (-67 min), CAP time (-90 min) and CAP rate (-23%) were already found on day 4 of treatment (sleep 2).(ABSTRACT TRUNCATED AT 250 WORDS)

Changes of cyclic alternating pattern (CAP) parameters in situational insomnia under brotizolam and triazolam.

The standardized scoring criteria of sleep can serve as a rough tool for monitoring the effects of psychoactive compounds, both in normal sleepers and in insomniac patients. More sensitive information on the impact of perturbing factors and drugs during sleep is supplied by the cyclic alternating pattern (CAP) parameters. In particular, CAP rate, which measures the amount of arousal instability during NREM sleep, has been proved of high reliability in a variety of clinical and pharmacological settings. The present study aimed at evaluating the activity of brotizolam (Br) 0.25 mg and triazolam (Tr) 0.25 mg on both conventional and CAP parameters in a model of situational insomnia of intermediate severity. Six middle-aged healthy subjects (three males and three females, aged 40-55 years) with no complaints about sleep, underwent a polysomnographic investigation according to a double-blind crossover design: placebo without noise (night 1), placebo with noise (night 2), brotizolam or triazolam without noise (nights 3 and 5), brotizolam or triazolam with noise (nights 4 and 6). The unperturbed nights consisted of standard recording conditions in a sound-protected sleep laboratory, whereas situational insomnia was accomplished by means of continuous white noise at 55 dBA delivered throughout the night. Subjects received medication orally at bedtime. An interval of at least 48 h was secured between consecutive recordings in the same individual. Compared to baseline conditions, situational insomnia was characterized by a shorter amount of total sleep (-40 min) and by an extension of intrasleep awakenings (+62 min).(ABSTRACT TRUNCATED AT 250 WORDS)

Automatic detection of cyclic alternating pattern (CAP) sequences in sleep: preliminary results.

OBJECTIVES: The analysis of cyclic alternating pattern (CAP) provides important microstructural information on arousal instability and on EEG synchrony modulation in the sleep process. This work presents a methodology for automatic classification of the micro-organization of human sleep EEG, using the CAP paradigm. METHODS: The classification system is composed of 3 parts: feature extraction, detection and classification. The feature extraction part is an EEG generation model-based maximum likelihood estimator. The detector part for the CAP phases A and B is done by a variable length template matched filter, while the classification criteria part is implemented on a state machine ruled-based decision system. RESULTS AND CONCLUSIONS: The preliminary results of the automatic classifier on a group of 4 middle-aged adults are presented. The high agreement between the detector and visual scoring is very promising in the achievement of a fully automated scoring system, although a more exhaustive evaluation program is needed.

Cyclic alternating pattern (CAP) and epilepsy during sleep: how a physiological rhythm modulates a pathological event.

OBJECTIVES: Epileptic susceptibility is triggered by the sleeping condition. However, both ictal and interictal events are not equally affected by the different sleep states. Besides the well-known dichotomy between non-REM sleep (high activation) and REM sleep (low activation), epileptic phenomena are deeply sensitive to the ongoing level of arousal. METHODS: During non-REM sleep the arousal level can be either unstable, as expressed by the repetitive sequences of the cyclic alternating pattern (CAP), or stable, as reflected by non-CAP. Phase A (arousal complex) and phase B (post-arousal rebound response) are the two basic components of the CAP cycle, which presents a 20-40 s periodicity. Three subtypes of A phases can be recognized: the A1 subtypes, which are thoroughly composed of K-complexes and delta bursts, and subtypes A2 and A3 dominated by moderate (A2) or prominent (A3) EEG desynchrony. RESULTS: As a manifestation of unstable sleep, CAP offers a favorable background for the occurrence of nocturnal motor seizures that in most cases arise in concomitance with a phase A. In primary generalized epilepsy (PGE) and in lesional epilepsies with fronto-temporal focus, activation of interictal discharges is high during CAP reaching the climax during phase A and the strongest inhibition during phase B. A lack of modulation is observed instead in epilepsy with benign rolandic spikes. In PGE, the interictal bursts are mostly associated with the highly synchronized phase A1 subtypes. CONCLUSIONS: The analysis of sleep microstructure based on CAP parameters offers a sensitive framework for exploring the linkage between dynamic EEG events and epileptic phenomena.

CAP components and EEG synchronization in the first 3 sleep cycles.

OBJECTIVE: There is consolidated evidence that stage changes in sleep are closely related to spontaneous EEG fluctuations centered on the 20-40 periodicity of the cyclic alternating pattern (CAP). The present investigation aimed at assessing the involvement of the different components of CAP in the process of build-up, maintenance and demolition of deep non-REM (NREM) sleep. METHODS: CAP parameters were quantified in the first 3 sleep cycles (SC1, SC2, SC3), selected from polysomnographic recordings of 25 healthy sound sleepers belonging to an extensive age range (10-49 years). Only ideal SCs were selected, i.e. the ones uninterrupted by intervening wakefulness and in which all stages were represented and linked in a regular succession of a descending branch, a trough and an ascending branch. RESULTS: Among the first 3 SCs, a total amount of 45 (SC1, 16; SC2, 13; SC3, 16) met the inclusion requirements. SCI contained the highest amount of slow wave sleep (43.7 min) and the lowest values of CAP rate (31.6%). The number of phase A1 subtypes remained unmodified across the 3 SCs (SC1, 48; SC2, 48; SC3, 48), whereas both subtypes A2 (SC1, 9; SC2, 14; SC3, 14) and A3 (SC1, 2; SC2, 8; SC3, 10) increased significantly (P<0.028 and P<0.0001, respectively). The A1 subtypes composed more than 90% of all the A phases collected in the descending branches and in the troughs, while the A2 and A3 subtypes were the major representatives (64.3%) of the A phases occurring in the ascending branches. CONCLUSIONS: Within the dynamic organization of sleep, the non-random distribution of CAP sequences, with their succession of slow (subtypes A1) and rapid (subtypes A2 and A3) EEG shifts, seem to be responsible for sculpturing EEG synchrony under the driving and alternating forces of NREM and REM sleep.

Sleep bruxism is a disorder related to periodic arousals during sleep.

There is evidence that sleep bruxism is an arousal-related phenomenon. In non-REM sleep, transient arousals recur at 20- to 40-second intervals and are organized according to a cyclic alternating pattern. Polysomnographic recordings from six subjects (two females and four males) affected by sleep bruxism (patients) and six healthy age-and gender-matched volunteers without complaints about sleep (controls) were analyzed to: (1) compare the sleep structure of bruxers with that of non-complaining subjects; and (2) investigate the relations between bruxism episodes and transient arousals. Patients and controls showed no significant differences in conventional sleep variables, but bruxers showed a significantly higher number of the transient arousals characterized by EEG desynchronization. Bruxism episodes were equally distributed between non-REM and REM sleep, but were more frequent in stages 1 and 2 (p < 0.0001) than in slow-wave sleep. The great majority of bruxism episodes detected in non-REM sleep (88%) were associated with the cyclic alternating pattern and always occurred during a transient arousal. Heart rate during the bruxism episodes (69.3+/-18.2) was significantly higher (p < 0.0001) than that during the pre-bruxing period (58.1+/-15.9). Almost 80% of all bruxism episodes were associated with jerks at the anterior tibial muscles. The framework of the cyclic alternating pattern offers a unified interpretation for sleep bruxism and arousal-related phenomena.