Relation between heart beat fluctuations and cyclic alternating pattern during sleep in insomnia patients.

Insomnia is a condition that affects the nervous and muscular system. Thirty percent of the population between 18 and 60 years suffers from insomnia. The effects of this disorder involve problems such as poor school or job performance and traffic accidents. In addition, patients with insomnia present changes in the cardiac function during sleep. Furthermore, the structure of electroencephalographic A-phases, which builds up the Cyclic Alternating Pattern during sleep, is related to the insomnia events. Therefore, the relationship between these brain activations (A-phases) and the autonomic nervous system would be of interest, revealing the interplay of central and autonomic activity during insomnia. With this goal, a study of the relationship between A-phases and heart rate fluctuations is presented. Polysomnography recording of five healthy subjects, five sleep misperception patients and five patients with psychophysiological insomnia were used in the study. Detrended Fluctuation Analysis (DFA) was used in order to evaluate the heart rate dynamics and this was correlated with the number of A-phases. The results suggest that pathological patients present changes in the dynamics of the heart rate. This is reflected in the modification of A-phases dynamics, which seems to modify of heart rate dynamics.

On separability of A-phases during the cyclic alternating pattern.

A statistical analysis of the separability of EEG A-phases, with respect to basal activity, is presented in this study. A-phases are short central events that build up the Cyclic Alternating Pattern (CAP) during sleep. The CAP is a brain phenomenon which is thought to be related to the construction, destruction and instability of sleep stages dynamics. From the EEG signals, segments obtained around the onset and offset of the A-phases were used to evaluate the separability between A-phases and basal sleep stage oscillations. In addition, a classifier was trained to separate the different A-phase types (A1, A2 and A3). Temporal, energy and complexity measures were used as descriptors for the classifier. The results show a percentage of separation between onset and preceding basal oscillations higher than 85 % for all A-phases types. For Offset separation from following baseline, the accuracy is higher than 80 % but specificity is around 75%. Concerning to A-phase type separation, A1-phase and A3-phase are well separated with accuracy higher than 80, while A1 and A2-phases show a separation lower than 50%. These results encourage the design of automatic classifiers for Onset detection and for separating among A-phases type A1 and A3. On the other hand, the A-phase Offsets present a smooth transition towards the basal sleep stage oscillations, and A2-phases are very similar to A1-phases, suggesting that a high uncertainty may exist during CAP annotation.

Nonlinear analysis of the change points between A and B phases during the Cyclic Alternating Pattern under normal sleep.

This study analyzes the nonlinear properties of the EEG at transition points of the sequences that build the Cyclic Alternating Pattern (CAP). CAP is a sleep phenomenon built up by consecutive sequences of activations and non-activations observed during the sleep time. The sleep condition can be evaluated from the patterns formed by these sequences. Eleven recordings from healthy and good sleepers were included in this study. We investigated the complexity properties of the signal at the onset and offset of the activations. The results show that EEG signals present significant differences (p<0.05) between activations and non-activations in the Sample Entropy and Tsallis Entropy indices. These indices could be useful in the development of automatic methods for detecting the onset and offset of the activations, leading to significant savings of the physician's time by simplifying the manual inspection task.

A novel method to assist the detection of the Cyclic Alternating Pattern (CAP).

This study proposes a novel method to assist the detection of the components that build up the Cyclic Alternating Pattern (CAP). CAP is a sleep phenomenon formed by consecutive sequences of activations (A1, A2, A3) and non-activations during nonREM sleep. The main importance of CAP evaluation is the possibility of defining the sleep process more accurately. Ten recordings from healthy and good sleepers were included in this study. The method is based on inferential statistics to define the initial and ending points of the CAP components based only on an initialization point given by the expert. The results show concordance up to 95% for A1, 85% for A2 and 60% for A3, together with an overestimation of 1.5 s in A1, 1.3 s in A2 and 0 s in A3. The total CAP rate presents a total underestimation of 7 min. Those results suggest that the method is able to accurately detect the initial and ending points of the activations, and may be helpful for the physicians by reducing the time dedicated to the manual inspection task.

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.

Effects of zolpidem on cyclic alternating pattern, an objective marker of sleep instability, in Japanese patients with psychophysiological insomnia: a randomized crossover comparative study with placebo.

OBJECTIVE: A placebo-controlled randomized crossover study to investigate the effects of zolpidem on sleep stability in Japanese insomniac patients was performed using the cyclic alternating pattern (CAP) rate, a polysomnographic marker that reflects sleep instability. METHODS: Seventeen patients (5 M and 12 F, mean age: 40.4+/-13.6 years) who met the International Classification of Sleep Disorders (ICSD) criteria for psychophysiological insomnia were evaluated. During the first period, patients were administered the placebo on the first night, followed by either zolpidem or the placebo on the second night (treatment night). The second crossover period was conducted after a minimum 3-day observation. Improvement in the overnight CAP rate was the primary endpoint. Secondary endpoints included the CAP variables, conventional sleep variables, EEG arousals, subjective evaluation of sleep quality (measured by means of a visual analogue scale and the St. Mary's Hospital Sleep Questionnaire), and drug safety. RESULTS: Zolpidem significantly decreased the overnight CAP rate values (57.6 vs. 39.0%, p=0.009) and improved "sleep depth" (p=0.044) and "sleep quality" (p=0.023) subjective questionnaire scores. Zolpidem also significantly improved VAS (p=0.036). The amount of time spent in sleep stages 3+4 was significantly increased by zolpidem without affecting the amounts of stage 2 and rapid eye movement (REM) sleep. Significant negative correlations were found when the sleep quality score was matched to the CAP rate (p=0.022). No serious adverse events occurred during the study. DISCUSSION: In Japanese patients with psychophysiological insomnia, zolpidem increased sleep stability by significantly improving the overnight CAP rate. Zolpidem also improved sleep depth and sleep quality, both subjectively and objectively.

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 challenge of chronic insomnia: is non-nightly hypnotic treatment a feasible alternative?

The adverse effects of insomnia on health and quality of life are matters receiving increasing attention. Yet, surveys have consistently shown that most people suffering from insomnia do not seek medical help, perhaps, in part, because of a concern of becoming dependent on hypnotic medication. The treatment of chronic insomnia poses a particular dilemma in that continuous hypnotic treatment is restricted in many countries to a maximum of 4 weeks, and behavioural treatment is not readily available. Non-nightly hypnotic treatment of chronic insomnia offers a promising alternative option for the many patients whose symptoms do not necessitate nightly drug intake, allaying fears of psychological dependence on medication and respecting regulatory constraints on hypnotic use while providing patients with adequate symptom relief. The practical feasibility and efficacy of this approach has been demonstrated with zolpidem using various treatment regimens and study designs. So far, six clinical trials have been completed on over 4000 patients. Published results show effective treatment of insomnia without any evidence of either adverse event associated with a discontinuous regimen or increased hypnotic use over the treatment period.

Fertility rate evaluation by laparoscopic approach in the experimental animal.

PURPOSE OF INVESTIGATION: The aim of the present study was to evaluate the effect of laparoscopic insemination (LAP) and natural mating (NM) on fertility rate in experimental animal (Ovis Aries Comisana) during the month of June. METHODS: For the experiment, 97 ewes were used. Laparoscopic insemination was performed with the frozen semen of three different Romanov rams: Laparoscopic insemination I (n = 24); Laparoscopic insemination 2 (n = 26); and laparoscopic insemination 3 (n = 28), and natural mating was performed with two different Ovis Aries Comisana rams with proven fertility: Natural mating I (n = 10); Natural mating 2 (n = 9). Estrus was synchronized with fluorogestone acetate impregnated intravaginal sponges (40 mg, 14 days). Pregnant mare serum gonadotrophin (Folligon, Intervet International) at a dose of 400 UI was given intramuscularly at sponge removal. Artificial insemination was carried out 60 hours after the removal of the sponges in the laparoscopic insemination groups. RESULTS: The mean pregnancy rate at ecographic diagnosis performed at about 36 days from sponge removal for the laparoscopic insemination and natural mating groups were respectively, 62.8% and 78.9% with no significant difference. CONCLUSION: The mean fertility rates for the LAP and NM groups were 56.0 and 73.4, respectively, with no significant difference.

Spike-wave discharge and the microstructure of sleep-wake continuum in idiopathic generalised epilepsy.

This review summarises all the evidences about the influence of different vigilance states on the occurrence of spike wave discharge (SWD) in idiopathic generalised epilepsy (IGE) patients. Numerous converging observations showed that full REM-sleep and alert wakefulness exert strong inhibition. A critical zone of vigilance which is a transitional state between waking and non-REM (NREM) sleep, and NREM sleep and REM sleep, has a promoting effect on the absence type spike wave discharge. Spike wave discharges are associated with phasic arousals without awakening and are attached to oscillation son the microstructural level of sleep, perpetuated by cyclic arousal events known as 'cyclic alternating pattern' (CAP), especially within the critical zone, but also along the whole sleep process. More specifically SWD seems to be attached to the 'A-phase' of CAP which is a reactive one and reflects synchronised NREM sleep EEG elements, like K-complexes, spindles and delta groups. The more slow wave elements are found in phase A--like in subtype A1--the more the coincidence with SWD occurs, and the more it is characterised by fast rhythms--as in subtype A2 and A3--the less the association with SWD could be observed. Since subtype A1 is associated with the first sleep cycle and with the descending branches of cycles, it is concluded that SWD appear in those dynamic moments of vigilance level oscillations which were characterised by strong sleep-like answers to arousal influences in high sleep pressure periods of sleep cyclicity. These data harmonize with another line of evidence suggesting that SWD represent the epileptic variant of the complex thalamocortical system function which is the substrate of NREM sleep EEG phenomena. In idiopathic generalised epilepsy there is a growing body of evidence that--as it was assumed by Gloor--spindles transform to SWD pattern. These data explain why those dynamic changes which evoke sleep responses are promoting for the occurrence of SWD. Adapting these data we offer a new interpretation to explain the strong activation effect of sleep deprivation in this kind of epilepsy. We assume that it is mainly due to the forced vigilance level oscillations, especially in morning, when elevated sleep pressure and circadian wake promoting forces, representing opposite tendencies, increase the amount of oscillations.

Sleep in Lennox-Gastaut syndrome: the role of the cyclic alternating pattern (CAP) in the gate control of clinical seizures and generalized polyspikes.

Non-rapid eye movement (NREM) sleep contains periods of arousal instability (cyclic alternating pattern or CAP) and periods of arousal stability (non-CAP). During CAP, arousal oscillates between higher (phase A) and lower (phase B) levels of activation. We evaluated the relationship between CAP and the occurrence of epileptic events, i.e. clinical seizures and generalized interictal discharges, during sleep in 10 patients with Lennox-Gastaut syndrome (LGS). The macro- and microstructure of sleep of 10 attended overnight polysomnograms were analyzed. Compared with 10 age- and gender-matched controls, patients with LGS had significantly less stage 2 and REM sleep and higher amounts of CAP rate (68% vs. 33%; P<0.0001). The number of generalized polyspike bursts per hour of sleep was highest in slow wave sleep (226.5+/-57.6) and lowest in REM sleep (3.9+/-1.5). The polyspike burst frequency was significantly greater (P<0.017) during CAP (213.2+/-60.1) than during non-CAP (100.3+/-40), and within CAP, generalized polyspikes occurred more often (P=0.005) during phase A (461.1+/-127.2) than during phase B (6.1+/-1.9). The total amount of generalized polyspike bursts identified in NREM sleep correlated positively both with the number of A phases containing at least one generalized polyspike (P=0.005) and with the mean number of polyspikes within each of these A phases (P<0.0001). Nocturnal clinical seizures occurred in 8 of the 10 patients and showed a similar trend. We conclude from our results that CAP modulates the occurrence of both clinical seizures and generalized epileptic discharges in LGS by means of a gate-control mechanism: an independent spike generator is inhibited in phase B and non-CAP and bursts with its intrinsic activity in phase A.

Combined influence of cyclic arousability and EEG synchrony on generalized interictal discharges within the sleep cycle.

PURPOSE: to analyze the activating role of cyclic alternating pattern (CAP) and EEG synchrony on generalized interictal paroxysms in the first part of the night, when all sleep patterns are represented. METHODS: nocturnal polysomnographic investigation was accomplished on a randomized series of 18 subjects with an active form of primary generalized epilepsy (PGE), but only six patients showed a complete and regular profile of the first two sleep cycles (SCs). Completeness and regularity of the selected SCs consisted in the absence of intervening wakefulness, in the presence of all sleep stages, and in the identification of three main units, (a) a descending branch, dominated by the build-up of EEG synchrony in the transition from light to deep non-rapid eye movement (NREM) sleep; (b) a trough, where the magnitude of EEG synchrony is greatest and gives rise to stages 3 and 4; (c) an ascending branch characterized by a decrease of EEG synchrony preceding the onset of rapid eye movement (REM) sleep. Generalized paroxysms were evaluated in terms of discharge rates (number of interictal bursts per minute of sleep) and distribution within the investigated sleep parameters. RESULTS: the discharge rates decreased from SC1 to SC2, with higher values quantified during NREM sleep (mean, 2.8) compared with REM sleep (mean, 0.8). Both SCs showed a progressive decrease of activation across the three units, from the highest discharge rates reached during the descending branches (mean, 3.6) to the more attenuated discharge rates during the troughs (mean, 2.4) down to the lowest rates during the ascending limbs (mean, 1.1). The magnitude of activation during the descending branches was closely related to the CAP condition (mean, 5.2) and to the powerful effect of phase A (mean, 13.9). The great majority (82%) of EEG discharges occurring in phase A were distributed within the A1 subtypes (identified by sequences of k-complexes or delta bursts). CONCLUSIONS: within the first two SCs, the features of NREM sleep endowed with the major activating power on generalized bursts are represented by the rise of EEG synchrony (descending branch) and by the A phases of CAP involved in the regulation of its build-up.

Superovulation in ewes by a single injection of pFSH dissolved in polyvinylpyrrolidone (PVP): effects of PVP molecular weight, concentration and schedule of treatment.

Three experiments were carried out to evaluate induction in ewes of superovulation and embryo production by a single injection of a porcine pituitary extract (pFSH) dissolved in polyvinylpyrrolidone (PVP), investigating the effects of PVP molecular weight and its concentration (Experiment I), time and method of treatment (Experiments II and III). All ewes were synchronized for estrus by vaginal sponges impregnated with fluorogestone acetate (FGA; 30 mg, 9 days) plus PGF(2alpha) (Cloprostenol, 50 microg, 48h before sponge removal - s.r.), and superovulated by 250 IU pFSH. In Experiment I, 60 Gentile di Puglia ewes were subdivided into five experimental groups (n = 12): Group A, the control, received six decreasing intramuscular (i.m.) doses of pFSH, 12 h apart, beginning 48h before s.r.; Groups B and C were given 48 h before s.r. a single i.m. injection of pFSH dissolved in PVP with MW = 10,000, respectively, at concentrations of 15 and 30% w/v; Groups D and E received the same treatments as for B and C using PVP with MW = 40,000. None of the pFSH-PVP treatments were effective in inducing superovulation. In Experiment II, 22 Leccese ewes were subdivided into two groups (n = 11): Group A, control received i.m. four decreasing doses of pFSH, beginning 24 h before s.r., 12h apart; Group B was given a single i.m. injection of pFSH dissolved in PVP (MW = 40,000 at 30% w/v), 24 h before s.r. The pFSH-PVP treatment provided an ovulation rate similar to the control and tended to enhance embryo yield (4.4 versus 2.4, P>0.05). In Experiment III, 60 Leccese ewes were subdivided into six treatment groups (n = 10). Groups A and D served as controls and received i.m. 12 h apart, six doses (from 48 h before s.r.) and four doses (from 24h before s.r.) of pFSH, respectively. Groups B and C were treated by a single injection of pFSH in PVP (MW = 10,000; 30% w/v) 48 h before s.r., respectively by i.m. or subcutaneous (s.c.) administration. Groups E and F received the same treatments as for B and C 24 h before s.r. Intramuscular pFSH-PVP administration 24 h before s.r. provided an ovulation rate (8.1), mean numbers of ova recovered (5.6) and fertilized (4.2) comparable to the six or four dose treatments and significantly higher (P <0.01) compared to the pFSH-PVP treatment carried out i.m. 48 h before s.r. These results show that a single injection of pFSH dissolved in PVP at 30% w/v, performed i.m. 24 h before s.r., is able to induce a superovulatory response comparable to that following multiple injection treatment, regardless of PVP molecular weight.

[Neurophysiological basis of insomnia: role of cyclic alternating patterns]. / Les bases neurophysiologiques de l'insomnie: le rôle des tracés alternant cycliques (CAP).

During non-REM (NREM) sleep it is possible to identify two complementary conditions of arousal stability and arousal instability. Unstable sleep, which can be detected in all stages, is expressed by the recurrence of arousal complexes (sequences of K-complexes, delta bursts, K-alpha, conventional arousals), which translate a brief (10-15 s) activation of the sleeping brain. These repetitive arousal complexes compose the cyclic alternating pattern (CAP). During stable NREM sleep, arousal complexes are rare or absent and the EEG lacks any cyclic pattern (non-CAP). CAP is a spontaneous feature of normal sleep as it is typically involved in stage changes and nocturnal motor activity. The physiological amount of CAP rate (ratio of CAP time to NREM sleep time) varies with age according to a U-shape curve. Within these ranges, sleep is perceived as continuous and restorative. Conversely, an excess of CAP rate fragments sleep and impairs its quality. Polysomnographic investigation reveals that untreated insomniac patients exhibit significantly higher values of CAP rate compared to healthy sleepers. Effective hypnotic treatment restores physiological amounts of CAP rate, with specific differences between the administered drugs. The sensitivity of CAP parameters to drug manipulation can provide circumscribed information on the hypnotic properties of active compounds.

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.

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.

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.

Cyclic alternating pattern and spectral analysis of heart rate variability during normal sleep.

The natural arousal rhythm of non-rapid eye movement (NREM) sleep is known as the cyclic alternating pattern (CAP), which consists of arousal-related phasic events (Phase A) that periodically interrupt the tonic theta/delta activities of NREM sleep (Phase B). The complementary condition, i.e. non-CAP (NCAP), consists of a rhythmic electroencephalogram background with few, randomly distributed arousal-related phasic events. Recently, some relation between CAP and autonomic function has been preliminarily reported during sleep in young adults by means of spectral analysis of heart rate variability (HRV). The present study was aimed at analysing the effects of CAP on HRV in a group of normal children and adolescents. Six normal children and adolescents (age range 10.0-17.5 y) were included in this study. All-night polygraphic recordings were performed after adaptation to the sleep laboratory. Six 5-min epochs were selected from sleep Stage 2 and six from Stages 3 and 4 (slow-wave sleep), both in CAP and NCAP conditions. From such epochs, a series of parameters describing HRV was then calculated, in both time and frequency domains, on the electrocardiographic R-R intervals. Statistical comparison between CAP and NCAP epochs revealed a significant difference for most of the frequency domain parameters (increase of the low-frequency band, increase of the low-frequency/high-frequency ratio and decrease in the high-frequency band during CAP) both in Stage 2 and in slow-wave sleep. Our results demonstrate that the physiological fluctuations of arousal during sleep described as CAP are accompanied by subtle, but significant, changes in balance between the sympathetic and vagal components of the autonomic system.