Sleep Microstructure Research Articles

The relation between abnormal behaviors and REM sleep microstructure in patients with REM sleep behavior disorder

Objective To investigate the temporal relation between rapid eye movement (REM) sleep microstructure (REMs, EMG activity) and motor events in REM sleep behavior disorder (RBD). Methods Polysomnographic records of eight patients with RBD were analyzed and compared with those of eight sex- and age-matched controls. We examined sleep microstructure for REM sleep with and without REMs and phasic chin EMG activity and their temporal relation to motor events on video. Results All types of motor events were either more frequent in RBD patients than in controls ( P ⩽ 0.007) or present solely in RBD patients. In RBD, major motor events were significantly more frequent during REM sleep with REMs than during REM sleep without REMs (violent, 84.0% vs. 16.0%, P < 0.001; complex/scenic behavior, 78.1% vs. 23.2%, P < 0.001; major jerks, 77.5% vs. 20.3%, P < 0.001), whereas minor motor activity was evenly distributed (54.1% vs. 45.9%, P = 0.889). Controls showed predominantly minor motor activity with rare myoclonic body jerks. The distribution of motor events did not differ between REM sleep with and without REMs (40.9% vs. 59.1%, P = 0.262). Conclusions In RBD, major motor activity is closely associated with REM sleep with REMs, whereas minor jerks occur throughout REM sleep. This finding further supports the concept of a dual nature of REM sleep with REMs and REM sleep without REMs and implies a potential gate control mechanism of REM sleep with REMs for the manifestation of elaborate or violent behaviors in RBD.

Aircraft noise: Effects on macro- and microstructure of sleep

Objective The effects of aircraft noise on sleep macrostructure (Rechtschaffen and Kales) and microstructure (American Sleep Disorders Association [ASDA] arousal criteria) were investigated. Patients and methods For each of 10 subjects (mean age 35.3 years, 5 males), a baseline night without aircraft noise (control), and two nights with exposure to 64 noise events with a maximum sound pressure level (SPL) of either 45 or 65 dBA were chosen. Spontaneous and noise-induced alterations during sleep classified as arousals (ARS), changes to lighter sleep stages (CSS), awakenings including changes to sleep stage 1 (AS1), and awakenings (AWR) were analyzed. Results The number of events per night increased in the order AWR, AS1, CSS, and ARS under control conditions as well as under the two noise conditions. Furthermore, probabilities for sleep disruptions increased with increasing noise level. ARS were observed about fourfold compared to AWR, irrespective of control or noise condition. Conclusions Under the conditions investigated, different sleep parameters show different sensitivities, but also different specificities for noise-induced sleep disturbances. We conclude that most information on sleep disturbances can be achieved by investigating robust classic parameters like AWR or AS1, although ASDA electroencephalographic (EEG) arousals might add relevant information in situations with low maximum SPLs, chronic sleep deprivation or chronic exposure.

Effects of a Mandibular Repositioning Appliance on Sleep Structure, Morning Behavior and Clinical Symptomatology in Patients with Snoring and Sleep-Disordered Breathing

Background: Mandibular repositioning appliances (MRAs) have become an established treatment for snoring and sleep-disordered breathing – though most studies only focused on the evaluation of respiratory variables. Methods: This single-blind, placebo-controlled case-series study investigated the effects of an individually adjustable MRA on psychopathology, macro-/microstructure of sleep, periodic leg movements, morning performance, mood/affect and psychophysiology. Fifty patients (37 males) aged 59.7 ± 10.3 years, suffering from primary snoring (7), mild (22), moderate (15) and severe apnea (6), spent 4 nights in the sleep laboratory (adaptation, placebo, drug and MRA night). The drug night is not subject of the present paper. Results: Confirmatory statistics showed an improvement of the snoring index by 72%. Descriptively, the apnea index and the apnea-hypopnea index normalized. A clinical improvement was seen in the Pittsburgh Sleep Quality Index, the Zung Anxiety/Depression Scales and the Epworth Sleepiness Scale. The restless legs syndrome also improved. Polysomnographically, sleep stages REM and 4 as well as REM latency increased, stage 3, movement time, stage shifts and periodic leg movements decreased, as did all arousal measures. Subjectively, morning well-being, drive, affectivity and wakefulness improved. Objectively, attention, motor and reaction time performance, critical flicker frequency as well as muscular strength increased, diastolic blood pressure and the pulse rate decreased. Conclusion: Apart from its good therapeutic effects on snoring and respiratory variables (snoring showed complete or partial response in 68%, the apnea-hypopnea index in 67% of the apnea patients), the MRA also improved psychopathology, objective and subjective sleep and awakening quality.

EEG Arousal Norms by Age

Brief arousals have been systematically scored during sleep for more than 20 years. Despite significant knowledge concerning the importance of arousals for the sleep process in normal subjects and patients, comprehensive age norms have not been published. Seventy-six normal subjects (40 men) without sleep apnea or periodic limb movements of sleep, aged 18 to 70 years, slept in the sleep laboratory for 1 or more nights. Sleep and arousal data were scored by the same scorer for the first night (comparable to clinical polysomnograms) and summarized by age decade. There were no statistically significant differences for sex or interaction of sex by age (p > .5 for both). The mean arousal index increased as a function of age. Newman-Keuls comparisons (.05) showed arousal index in the 18- to 20-year and 21- to 30-year age groups to be significantly less than the arousal index in the other 4 age groups. Arousal index in the 31-to 40-year and 41-to 50-year groups was significantly less than the arousal index in the older groups. The arousal index was significantly negatively correlated with total sleep time and all sleep stages (positive correlation with stage 1 and wake). Brief arousals are an integral component of the sleep process. They increase with other electroencephalographic markers as a function of age. They are highly correlated with traditional sleep-stage amounts and are related to major demographic variables. Age-related norms may make identification of pathologic arousal easier.

Comparison of Polygraphic Parameters in Children With Adenotonsillar Hypertrophy With vs Without Obstructive Sleep Apnea

To compare the polygraphic parameters in children with adenotonsillar hypertrophy (ATH) with vs without obstructive sleep apnea (OSA). Prospective controlled study. Hospital-based pediatric otolaryngology practice. Children with ATH. The children enrolled in the study underwent polysomnography. According to the apnea index (AI) (a patient who has at least 1 episode of apnea per hour of sleep is considered to have apnea), they were classified as having ATH with OSA or ATH without OSA. We evaluated polysomnography parameters to describe the macrostructure of sleep (sleep efficiency, nonrapid eye movement stages 1-4, and rapid eye movement) and the microstructure of sleep (using electroencephalogram results and movement arousals) and respiratory events. Twenty children were classified as having ATH with OSA and 17 as having ATH without OSA. We found no significant differences in sleep macrostructure and microstructure between the ATH groups with vs without OSA. Apnea-hypopnea indices (AHI), respiratory disturbance events, hypopnea events in rapid eye movement and AHI, AI, respiratory disturbance events, obstructive events, hypopnea events, the duration of obstructive events, and hypopnea events during nonrapid eye movement were more frequent or of longer duration in children with OSA vs those without OSA (P < .05). Obstructive sleep apnea should be considered a disorder on the continuum of ATH. To our knowledge, our results clearly and for the first time demonstrate that more severe respiratory disturbances seem to be important risk factors for ATH to develop into OSA in children.

Detection of activation phases and quantification of coupling in NREM sleep EEG by pointwise transinformation

Background: The coupling dynamics of two time series can be assessed by pointwise transinformation (PTI). Due to its high temporal resolution, this algorithm is ideal for analysis of sleep microstructure. Different types of electroencephalographic (EEG) activation phases, like single K-complexes, K-complexes associated with spindle or alpha activity, K-complexes mixed with delta waves, and arousals, can be detected and changes in EEG coupling can be quantified. Methods: Nine hundred ninety-one one-minute EEG segments (C3-A2/C4-A1) containing the described types of activation phases were selected from the sleep EEGs of 12 healthy persons. PTI was calculated with 250 Hz resolution and an embedding dimension of 20. An averaged PTI curve was assessed for single K-complexes and K-complexes followed by spindle and alpha activity, respectively. Results: During background activity, PTI was nearly 0. With the onset of a K-complex, PTI increased significantly in a sequence of distinct phases (rising – peak – decay). For single K-complexes, the PTI curve had a nearly symmetric dome-shaped form. The decay phase was prolonged by subsequent spindle or alpha activity. In K-complexes mixed with delta activity and in arousals, repetitive maxima of PTI were obtained. The durations of arousals and their coupling phases were correlated ( r = 0.83). Conclusions: PTI displays the coupling dynamics of the sleep EEG with high resolution. It detects phases of activation represented by single K-complexes and various types of arousals. These induce a specific run of the PTI curve clearly distinguishable from background activity. PTI might, therefore, prove useful in the analysis of sleep microstructure.

Fatigue and sleep disturbance in multiple sclerosis

Considering the association of sleep disturbance and fatigue in multiple sclerosis (MS), we investigated the presence of sleep disturbances that may be related to fatigue by using objective and subjective measures. We included 27 MS patients with fatigue, 10 MS patients without fatigue and 13 controls. The Pittsburgh sleep quality index score showed significant differences between patient groups and controls. Beck depression inventory scores were significantly higher in fatigued than non-fatigued patients. Comparison of patient groups and controls revealed significant differences for time in bed, sleep efficiency index, sleep continuity index, wake time after sleep onset, total arousal index and periodic limb movement arousal index. Our study confirms that MS causes sleep fragmentation in terms of both macro and microstructure. Fatigue in MS could be partially explained by disruption of sleep microstructure, poor subjective sleep quality and depression.

Micro- and macrostructure of sleep EEG

Electroencephalogram (EEG) provides important and unique information about the sleeping brain. Polysomnography was the major method of sleep analysis and the main diagnostic tool in sleep medicine. The standard interpretation of polysomnographic recordings describes their macrostructure in terms of sleep stages, delineated according to R&K scoring criteria. Several descriptors of sleep microstructure rely on the quantification of sleep spindles and slow wave activities, detection of arousals, etc. However, these descriptors are usually assessed by means of substantially different signal processing (or visual) methods. This hinders possibilities of combining their results into a coherent description of the sleep process. This study proposes a solution to these problems in terms of a framework based upon adaptive time-frequency approximations - a recent, advanced method of signal processing. The proposed approach provides compatibility with the visual EEG analysis and standard definitions of EEG structures and describes both the macro- and microstructure of sleep EEG. Adaptive time-frequency approximations of signals calculated by means of the matching pursuit (MP) algorithm allow for the discrimination between series of unrelated structures and oscillatory activity. The detection, parametrization, and description of all these features of sleep are based upon the same unifying approach

Neurophysiological aspects of primary insomnia: Implications for its treatment

Insomnia has usually been studied from a behavioral perspective. Somatic and/or cognitive conditioned arousal was shown to play a central role in sleep complaints becoming chronic, and was used as a starting point for the development of treatment modalities. The introduction of the neurocognitive perspective, with its focus on cortical or CNS arousal, has given rise to a renewed interest in the neurophysiological characteristics of insomnia. Recent research, using quantitative EEG, neuroimaging techniques and the study of the microstructure of sleep, suggests a state of hyperarousal with a biological basis. Furthermore, insomnia might not be restricted to sleep complaints alone because it appears to be a 24-h disorder, affecting several aspects of daytime functioning as well. These new findings have implications for the treatments used and indicate that a focus on cortical or CNS arousal should be pursued. As such, the use of EEG neurofeedback, a self-regulation method based on the paradigm of operant conditioning, might be a promising treatment modality. Preliminary results for insomnia and successful applications for other disorders suggest that this treatment can have the necessary stabilizing effects on the EEG activity, possibly resulting in a normalizing effect on daytime as well as nighttime functioning.

Sleep Disturbances in Patients with Post-Traumatic Stress Disorder

Subjective reports of sleep disturbance indicate that 70-91% of patients with post-traumatic stress disorder (PTSD) have difficulty falling or staying asleep. Nightmares are reported by 19-71% of patients, depending on the severity of their PTSD and their exposure to physical aggression. Objective measures of sleep disturbance are inconsistent, with some studies that used these measures indicating poor sleep and others finding no differences compared with non-PTSD controls. Future research in this area may benefit from examining measures of instability in the microstructure of sleep. Additionally, recent findings suggest that sleep disordered breathing (SDB) and sleep movement disorders are more common in patients with PTSD than in the general population and that these disorders may contribute to the brief awakenings, insomnia and daytime fatigue in patients with PTSD. Overall, sleep problems have an impact on the development and symptom severity of PTSD and on the quality of life and functioning of patients. In terms of treatments, SSRIs are commonly used to treat PTSD, and evidence suggests that they have a small but significant positive effect on sleep disruption. Studies of serotonin-potentiating non-SSRIs suggest that nefazodone and trazodone lead to significant reductions in insomnia and nightmares, whereas cyproheptadine may exacerbate sleep problems in patients with PTSD. Prazosin, a centrally acting alpha1-adrenoceptor antagonist, has led to large reductions in nightmares and insomnia in small studies of patients with PTSD. Augmentation of SSRIs with olanzapine, an atypical antipsychotic, may be effective for treatment-resistant nightmares and insomnia, although adverse effects can be significant. Additional medications, including zolpidem, buspirone, gabapentin and mirtazapine, have been found to improve sleep in patients with PTSD. Large randomised, placebo-controlled trials are needed to confirm the above findings. In contrast, evidence suggests that benzodiazepines, TCAs and MAOIs are not useful for the treatment of PTSD-related sleep disorders, and their adverse effect profiles make further studies unlikely. Cognitive behavioural interventions for sleep disruption in patients with PTSD include strategies targeting insomnia and imagery rehearsal therapy (IRT) for nightmares. One large randomised controlled trial of group IRT demonstrated significant reductions in nightmares and insomnia. Similarly, uncontrolled studies combining IRT and insomnia strategies have demonstrated good outcomes. Uncontrolled studies of continuous positive airway pressure for SDB in patients with PTSD show that this treatment led to significant decreases in nightmares, insomnia and PTSD symptoms. Controlled studies are needed to confirm these promising findings.

Alteration of sleep microstructure in psychiatric disorders

Macrostructure describes the temporal organization of sleep based on successive epochs of conventional length, while microstructure, which is analyzed on the basis of the scoring of phasic events, provides additional important dynamic characteristics in the evaluation of both normal and pathological sleep processes. Relationships between sleep, sleep disorders, and psychiatric disorders are quite complex, and it clearly appears that both the macrostructure and the microstructure of sleep are valuable physiologically and clinically. Psychiatric patients often complain about their sleep, and they may show sleep abnormalities that increase with the severity of their illness. Changes in the occurrence and frequency of phasic events during sleep may be associated with specific psychiatric disorders, and may provide valuable information for both diagnosis and prognosis of these disorders.

Atypical sleep architecture and the autism phenotype

A growing body of evidence indicates that people with autism frequently experience sleep disorders and exhibit atypical sleep architecture. In order to establish whether sleep disorders truly belong to the autism spectrum disorder (ASD) phenotype, we conducted a subjective and objective study of sleep in a group of high-functioning adults with ASD but without sleep complaints, psychiatric disorders or neurological comorbidity. We compared the subjective data of 27 ASD participants with those of 78 healthy controls matched for chronological age and gender. Subjective measures of sleep in the clinical group were compatible with insomnia and/or a tolerable phase advance of the sleep-wake cycle. Subjective data were confirmed by objective laboratory sleep recordings in a subset of 16 patients and 16 controls. Persons with autism presented with a longer sleep latency (P < 0.04), more frequent nocturnal awakenings (P < 0.03), lower sleep efficiency (P < 0.03), increased duration of stage 1 sleep (P < 0.02), decreased non-REM sleep (stages 2 + 3 + 4, P < 0.04) and slow-wave sleep (stages 3 + 4, P < 0.05), fewer stage 2 EEG sleep spindles (P < 0.004), and a lower number of rapid eye movements during REM sleep (P < 0.006) than did control participants. On clinical scales, the scores of persons with ASD on the Beck Depression Inventory were similar to those of persons without, but their trait anxiety scores on the Spielberger Anxiety Scale were higher (P < 0.02). The state anxiety scores of the Spielberger scale and cortisol levels were the same in the two groups. Objective total sleep time correlated negatively with the Social (-0.52, P < 0.05) and Communication (-0.54, P < 0.02) scales of the Autism Diagnostic Interview-Revised. The sleep of clinical subgroups (10 with high-functioning autism, six with Asperger syndrome) did not differ, except for the presence of fewer EEG sleep spindles in the Asperger syndrome subgroup (P < 0.05). In conclusion, these findings indicate that atypicalities of sleep constitute a salient feature of the adult ASD phenotype and this should be further investigated in younger patients. Moreover, the results are consistent with an atypical organization of neural networks subserving the macro- and microstructure of sleep in ASD. We are furthering this research with quantified analysis of sleep EEG.

Positive Airway Pressure Therapy of OSA

Positive airway pressure is standard therapy for patients with obstructive sleep apnea. It comes in three basic varieties: (1) continuous positive airway pressure (CPAP), (2) bilevel positive airway pressure (BPAP), and (3) autotitrating positive airway pressure (APAP). When properly titrated, positive airway pressure devices minimize the number of sleep-related breathing disorder events, often producing dramatic results. Sleep-related breathing may completely normalize, specific stages of sleep may selectively rebound due to having been chronically suppressed, sleep microstructure may improve, and the patient may awaken feeling refreshed for the first time in years. The specific indications and criteria for recommending APAP, BPAP, and CPAP therapy are reviewed. The titration process is presented in a step-by-step manner and titration grading is explained. Issues surrounding the interface, acceptance, utilization, and side-effects are discussed. Finally, we present an assortment of approaches for troubleshooting clinical problems commonly encountered among patients being treated with positive airway pressure therapy.

Análisis espectral de la variabilidad del ritmo cardíaco y activación cardíaca durante el despertar en el sonambulismo

In sleepwalking, a disorder that is characterised by partial waking, the subject experiences an alteration of the microstructure of sleep that can affect autonomous activity during sleep and the waking state. In order to evaluate any possible upset in the regulation of autonomous functioning in sleepwalkers during sleep and the waking state, we conducted a spectral analysis of their heart rate variability (HRV) during both sleep and the waking state. Spectral analysis of HRV was conducted in the group of 10 sleepwalkers and 10 normal controls during sleep and during the waking state in both the horizontal and vertical positions. Their pattern of cardiac activation was also analysed during different types of arousal. There were no differences between the group of sleepwalkers and the control group in the parameters used in the spectral analysis of HRV during sleep and in the horizontal position during the waking state. Sleepwalkers showed a greater shift in the sympathovagal balance in favour of sympathetic activity, as a response to standing. During the 5-minute sequences immediately before the start of pathological arousal in sleepwalkers, the total energy in the spectral analysis of HRV was seen to increase. No differences were found between the patterns of cardiac activation displayed by the groups of patients and normal subjects during several different types of arousal. Autonomous reactivity was seen to be altered as a response to the orthostatic load in sleepwalkers, which could be the consequence of the instability of these patients' sleep. The increase in the total energy in the spectral analysis of HRV immediately before pathological arousal during NREM 4 sleep in sleepwalkers suggests that autonomous activation precedes cortical arousal.

Sleep microstructure and neurodegeneration as measured by [123I]?-CIT SPECT in treated patients with Parkinson?s disease

Along with spindles, K-complexes are well known hallmarks of stage 2 (S2) sleep. However, little is known about their quantity in S2 sleep of patients with Parkinson's disease (PD). Sleep laboratory, Department of Neurology, University of Vienna, Austria. Whole-night polysomnography (PSG) was performed in twelve treated PD patients and ten healthy controls without history of sleep complaints. The quantity of spontaneous K-complexes, K-alpha-complexes, and sleep spindles in one hour S2 sleep, distributed in four epochs of 15 minutes all through the night, were visually selected and analysed. The quantity and the temporal course of these phasic events were compared with the quantity in age-matched healthy controls. Nine of the twelve PD patients underwent [123I]beta-CIT SPECT for calculating dopamine transporter binding in the striatum and serotonin transporter density in the thalamus-hypothalamus region. There was no difference between the quantity of K-complexes, K-alpha-complexes, and sleep spindles in PD patients and in the healthy control group. K-complexes but not sleep spindles decreased over the night in both groups. The number of sleep spindles did not correlate with the dopamine transporter binding in the striatum or the serotonin binding in the thalamic/hypothalamic region. K-complexes and sleep spindles are not reduced and do not seem to be related to the degree of dopaminergic degeneration in treated PD patients.

A general automatic method for the analysis of NREM sleep microstructure

Objective To define a unified method for the automatic recognition and quantitative description of EEG phasic events of sleep microstructure occurring during NREM sleep, particularly arousals, phase A subtypes of cyclic alternating pattern and spindles. Methods The NREM sleep EEG of 10 normal young subjects was examined in order to recognize formal phasic events of sleep microstructure. The following ‘formal’ events (i.e. events defined exclusively on the basis of automatic analysis criteria) were classified: arousals, A1-phases (A-phases not including arousals) and A2- and A3-phases (A-phases including arousals). Spindle bursts, corresponding to visually recognized spindles, were also formally defined. The identification of these events was carried out following a three-step procedure: (1) computation of band-related descriptors derived from the EEG signal, (2) introduction of suitable thresholds and (3) application of simple logical principles, i.e. an exclusion principle and an overlapping principle. Results Formal A-phases, arousals and spindle bursts showed spectral characteristics which were consistent with visual inspection. The value of the parameter Correctness for the recognition of the A-phases was 83.5%. In particular, the different physiological distribution of the A-phases in Stage 2 preceding slow wave sleep with respect to Stage 2 preceding REM sleep was confirmed. Conclusions The proposed method provides a unified quantitative approach to the study of sleep microstructure. Visually defined events can be reliably identified by means of automatic recognition.

Is insomnia a neurophysiological disorder? The role of sleep EEG microstructure

Unlike other sleep disorders, such as sleep-related breathing disorders and periodic limb movement (PLM), the nature and severity of which are quantified by specific respiratory and motor indexes, no apparent organ dysfunction underlies several cases of insomnia (in particular primary insomnia), which can be objectively diagnosed only through the structural alterations of sleep. Polysomnography (PSG) investigation indicates that insomnia is the outcome of a neurophysiological disturbance that impairs the regulatory mechanisms of sleep control, including sleep duration, intensity, continuity and stability. In particular, analysis of sleep microstructure has permitted to establish that etiologic factors of different nature (including depressive disorders) exert a common destabilizing action on sleep, which is reflected in an increase of cyclic alternating pattern (CAP) rate. These premises allow us to attribute a more objective identity to insomnia, which risks otherwise to be considered as an unexplainable mental complaint. In conclusion, PSG remains the “gold standard” for measuring sleep, and especially insomnia.

Is insomnia a neurophysiological disorder? The role of sleep EEG microstructure

Unlike other sleep disorders, such as sleep-related breathing disorders and periodic limb movement (PLM), the nature and severity of which are quantified by specific respiratory and motor indexes, no apparent organ dysfunction underlies several cases of insomnia (in particular primary insomnia), which can be objectively diagnosed only through the structural alterations of sleep. Polysomnography (PSG) investigation indicates that insomnia is the outcome of a neurophysiological disturbance that impairs the regulatory mechanisms of sleep control, including sleep duration, intensity, continuity and stability. In particular, analysis of sleep microstructure has permitted to establish that etiologic factors of different nature (including depressive disorders) exert a common destabilizing action on sleep, which is reflected in an increase of cyclic alternating pattern (CAP) rate. These premises allow us to attribute a more objective identity to insomnia, which risks otherwise to be considered as an unexplainable mental complaint. In conclusion, PSG remains the “gold standard” for measuring sleep, and especially insomnia.

Microstructure of sleep in eating disorders: preliminary results.

Attempts to analyse the sleep structure of patients with eating disorders have so far led to conflicting results. Polygraphic findings suggest that patients with bulimia nervosa are not easily distinguishable from age-matched controls, whereas anorexic patients show some abnormalities in sleep efficiency and sleep architecture. Nevertheless, both bulimic and anorexic patients complain of poor quality sleep. The aim of this study was to evaluate the microstructure of sleep in anorexia and bulimia by analysing arousal (following the rules of the American Sleep Disorders Association) and the cyclic alternating pattern (CAP). The results confirmed the presence of sleep disturbances in eating disordered patients: an increase in arousal length and the CAP rate. They also seem to confirm the findings of previous studies suggesting that altered sleep in eating disordered patients may be related to their body mass index (BMI) and psychopathological status.

Efectos de las crisis epilépticas en la arquitectura del sueño

Many studies have appeared in the literature that aim to analyse the influence of sleep and its stages on the behaviour of seizures, but very few look into the opposite effect, that is, the effect of the seizures on the structure of sleep. The influence exerted by a number of variables, such as the presence of seizures during the waking state prior to the study, the administration or withdrawal of antiepileptic drugs, sleep disorders during the night in the laboratory or the presence of concomitant sleep pathologies, together with the difficulties involved in monitoring or controlling all these factors gives rise to varying results in the publications examined. We offer a brief review of the components of sleep and its stages together with an update of the literature on the influence seizures exert on them.With regard to the macrostructure of sleep, there seems to be general agreement about the fact that nocturnal generalised seizures alter the architecture of sleep, with a reduction in the efficiency of sleep and a drop in the amount of REM sleep. There also appears to be a high degree of concurrence about how recurring partial seizures on the night of the study affect the pattern of sleep, REM sleep being especially sensitive. No generalised agreement exists concerning the influence exerted by isolated partial seizures or by the seizures that take place during the waking state prior to the night the recording is made. Studies into the influence exerted by seizures on the microstructure of sleep (CAP) are scarce and are limited to specific pathologies. A deeper understanding of these interactions will provide us with key data about the clinical manifestations and the physiopathology of epileptic diseases.