Changes in EEG power density during sleep laboratory adaptation in depressed inpatients.

BACKGROUND: The aim of the present study was to evaluate the first-night effect in depressed inpatients, using standard sleep measures as well as all-night spectral analysis of the sleep electroencephalogram (EEG). METHODS: Eighteen drug-free, depressed inpatients were studied for 3 consecutive nights in the hospital sleep laboratory. RESULTS: Visual sleep scoring results showed a slight but measurable first-night effect, characterized by a reduction of rapid eye movement (REM) sleep amount and increased wakefulness. Sleep EEG spectral analysis showed significantly reduced delta (p <.01) and theta (p <.05) power density in non-REM (NREM) sleep of the first night compared with that of the second and third nights. These differences were limited to the early part of the sleep period, a time during the night that is particularly vulnerable to the effects of depressive disorder. In contrast to the NREM sleep findings, spectral REM variables studied did not significantly vary across the three nights. CONCLUSIONS: The results obtained suggest that first-night data should not be simply discarded but could be used in subsequent analyses and could be considered useful in the evaluation of the sleep of depressed patients.     

EEG activities during elicited sleep onset REM and NREM periods reflect different mechanisms of dream generation. Electroencephalograms. Rapid eye movement.

OBJECTIVE: To be the first to compare EEG power spectra during sleep onset REM periods (SOREMP) and sleep onset NREM periods (NREMP) in normal individuals and relate this to dream appearance processes underlying these different types of sleep periods. METHODS: Eight healthy undergraduates spent 7 consecutive nights in the sleep lab including 4 nights for SOREMP elicitation using the Sleep Interruption Technique. This enabled us to control preceding sleep processes between SOREMP and NREMP. EEG power spectra when participants did and did not report 'dreams' were compared between both types of sleep. Sleep stages, subjective measurements including dream property scores, sleepiness, mood, and tiredness after awakenings were also examined to determine their consistency with EEG findings. RESULTS: Increased alpha EEG activities (11.72-13.67 Hz) observed mainly in the central area were related to the absence of SOREMP dreams and appearance of NREMP dreams. Analyses of sleep stages combining two studies (16 participants) also supported the Fast Fourier Transform findings, showing that when dreams were reported there were decreased amounts of stage 2 and increased stage REM in SOREMP and increased stage W in NREMP. SOREMP dreams were more bizarre than NREMP dreams. Participants felt more tired after SOREMP with dreams than without dreams, while the opposite was observed after NREMP episodes. CONCLUSIONS: EEG power spectra patterns reflected different physiological mechanisms underlying generation of SOREMP and NREMP dreams. The same relationships were also reflected by sleep stage analyses as well as subjective measurements including dream properties and tiredness obtained after awakenings. This study not only supports the hypothesized relationships between REM mechanisms and REM dreams as well as arousal processes and NREM dreams, it also provides a new perspective to dream research due to its unique techniques to awaken participants and collect REM dreams during experimentally induced SOREMP.     

Band-specific electroencephalogram and brain cooling abnormalities during NREM sleep in patients with winter depression.

BACKGROUND: We previously reported that delta wave activity and facial skin temperatures, an index of brain cooling activity, were both abnormal during sleep in patients with winter depression (SAD). Because other electroencephalographic (EEG) frequencies may also convey relevant thermal, homeostatic, and circadian information, we sought to spectrally analyze delta, theta, alpha, and sigma frequencies during sleep from 23 patients with SAD and 23 healthy control subjects. METHODS: We computed means for delta, theta, alpha, and sigma power during both NREM and REM sleep. We also generated 22 cross-correlation functions for each group by crossing facial and rectal temperature with each other, as well as with delta, theta, alpha, and sigma frequencies. RESULTS: We found that delta, theta, and alpha frequency activities were all increased during NREM, but not REM sleep, in patients with SAD. In addition, there were significant and abnormal cross-correlations between facial temperatures and delta and theta frequencies during NREM sleep in patients with SAD. CONCLUSIONS: Patients with winter depression exhibit correlated abnormalities of sleep homeostasis and brain cooling during NREM sleep. Their EEG profiles during NREM sleep resemble the EEG profiles of subjects who have been sleep deprived. Further studies of NREM sleep homeostasis in patients with SAD seem warranted.     

EEG sleep in young depressives: first and second night effects

The sleep electroencephalogram (EEG) of young, drug-free, recurrently depressed outpatients was analyzed for 2 nights and was compared to age-matched controls using a variety of standard and computerized measures of sleep activity. On the first night, young depressives showed significantly greater difficulty in falling asleep and decreased sleep efficiency. Sleep architecture differences between the young depressives and controls were highlighted by increased percentages of Stage 2 sleep and major decreases in Stages 3 and 4 (delta wave) sleep among the depressives, as indicated by either period analyses or spectral analysis. The greatest differences in delta wave activity during night 1 were found in the first two (non-rapid eye movement (NREM) periods as measured by period analysis (NREM period 1, p less than 0.04; NREM period 2, p less than 0.001--average delta wave count) or by spectral analysis for the first 100 min of sleep (0.5-2.0 Hz). In contrast to the NREM sleep findings, various REM variables, including REM latency did not significantly distinguish the two subject groups for either night 1 or 2. Stepwise discriminant analysis demonstrated that night 1 sleep latency and delta wave counts during the second NREM period correctly classified 100% of all 16 individuals studied. The only differences between the young depressed patients and controls that remained on night 2 were significant reductions in slow-wave sleep as quantified by the computerized methods. Taken together, these findings suggest that the EEG response of young outpatients to the first night's stay in a sleep laboratory may be a useful tool for the diagnosis of depression in this age group. In addition, the use of computerized methods in this study point to an underlying deficit in delta sleep waveforms as being a prominent feature of the sleep of young depressed subjects.     

Baseline and post-deprivation recovery sleep in SCN-lesioned rats

In humans, advancing age alters sleep patterns, reducing high voltage NREM sleep, sleep bout length, and delta power during NREM sleep. Although the mechanism by which these alterations occur is unknown, age-related changes in normal circadian processes may play a role. Increased age produces histological and functional changes in the suprachiasmatic nucleus (SCN), and alters the amplitude and phase of circadian rhythms. To examine the relationship between SCN function and age-related changes in sleep, we produced radiofrequency (RF) lesions of the SCN in rats of different ages and examined sleep behavior before and after sleep deprivation. Three-, 12- and 18-month-old rats received RF or sham lesions of the SCN. After verifying loss of circadian rhythm, 24-h EEG/EMG/temperature recordings were made in dim light before and after 24 h of sleep deprivation using the disk-over-water method. Age-related changes in NREM sleep, sleep bout length, and delta EEG power persisted despite SCN lesions. SCN lesions in all age groups increased baseline NREM sleep by 4% and NREM delta power by 15%, and decreased REM sleep by 10%. Although SCN lesions initially produced more REM and NREM sleep during recovery, 24-h values did not differ. Deteriorating SCN function is unlikely to cause the characteristic changes in sleep that occur with age. Our data also imply that an intact SCN slightly inhibits NREM sleep in the rat. Changes in NREM sleep and delta EEG power during recovery in lesioned rats suggest that the SCN may influence homeostatic regulation.     

Sleep following sport-related concussions

ObjectivesSleep and vigilance disorders are among the most commonly reported symptoms following a concussion. The aim of the study was thus to investigate the effects of sport-related concussions on subjective and objective sleep quality.MethodsTen concussed athletes and 11 non-concussed athletes were included. Concussed athletes had a history of 4.6 ± 2.1 concussions with at least one concussion during the last year. They were recorded for two consecutive nights in the laboratory and during a 10-min period of wakefulness. They completed questionnaires related to sleep quality and symptoms as well as neuropsychological tests and the CogSport computer battery.ResultsConcussed athletes reported more symptoms and worse sleep quality than control athletes, but no between-group differences were found on polysomnographic variables or on REM and NREM sleep quantitative EEG variables. However, concussed athletes showed significantly more delta activity and less alpha activity during wakefulness than did control athletes.ConclusionIn spite of the subjective complaints in sleep quality of concussed athletes, no change was observed in objective sleep characteristics. However, concussions were associated with an increase in delta and a reduction in alpha power in the waking EEG. Sport-related concussions are thus associated with wakefulness problems rather than sleep disturbances.     

Altered interaction between cardiac vagal influence and delta sleep EEG suggests an altered neuroplasticity in patients suffering from major depressive disorder

Jurysta F, Kempenaers C, Lancini J, Lanquart J‐P, van de Borne P, Linkowski P. Altered interaction between cardiac vagal influence and delta sleep EEG suggests an altered neuroplasticity in patients suffering from major depressive disorder. Objective: Major depressive disorder (MDD), which is associated with altered neuroplasticity and increased relative cardiac sympathic activity, enhances the risk of cardiovascular pathologies. Interaction between cardiac sympatho‐vagal indexes and delta sleep power is probably altered in MDD. Method: Sleep characteristics and cardiac sympatho‐vagal indexes of 10 depressive patients were compared to 10 control men across the first three non‐rapid eye movement (NREM)–REM cycles. Interaction between normalized high frequency (HF) and delta power bands was studied using coherence analysis. Results: Patients showed increased sleep latency, stage 1 and wake durations. No differences in heart rate variabilities were observed: Total power, HF and RR‐interval decreased from NREM to REM sleep and wakefulness in both groups. Gain value was lower in patients while coherence and phase shift were similar between groups. Modifications in HF appear 8 min before modifications in delta. Conclusion: Major depressive disorder is related to an altered link between cardiac vagal influence and delta sleep, suggesting disorders in cardiovascular controls and an altered neuroplasticity.     

Paradoxes of the first-night effect: a quantitative analysis of antero-posterior EEG topography.

OBJECTIVE: The first-night effect (FNE) is a common issue in sleep research. Being considered fragmented and poorly efficient, the adaptation night is discarded for data analysis. The present study aims to provide a quantitative and topographical EEG analysis of this phenomenon. METHODS: Eight healthy subjects slept for two consecutive nights (adaptation (AD) and baseline (BSL)), and their polysomnography was visually scored and then submitted to spectral power analysis. RESULTS: The results showed a decreased quality and quantity of first-night sleep as indicated by more stage 1 and intrasleep wake, paralleled by a reduced sleep efficiency and a longer sleep onset latency. On the other hand, EEG quantitative data showed a more complex and apparently paradoxical picture. An increase in delta power was observed, particularly over the central areas during the first night, paralleled by an increased power in beta bin frequencies solely at posterior scalp locations. CONCLUSIONS: These results have been interpreted as caused by, respectively, a reduced total sleep time during the adaptation night and a cortical hyperactivity, typical of psychophysiological insomnia. The present results confirm the need to exclude the laboratory sleep adaptation night from data analysis since it is not a reliable index of sleep on subsequent nights as regards both visual scoring and quantitative EEG analysis. Finally, regional differences between REM and NREM sleep have been confirmed. Significance: This is the first attempt to evaluate the FNE with a quantitative approach to the antero-posterior EEG topography, providing both a Hz-by-Hz and a classical EEG band-based analysis.     

Rapid eye movement density shows trends across REM periods but is uncorrelated with NREM delta in young and elderly human subjects

Saccade-like eye movements are the most prominent phasic component of rapid eye movement (REM) sleep. Eye movement density (EMD) appears to be negatively related to sleep depth. Thus, EMD is depressed by sleep deprivation. We sought to determine in 19 young normal (YN) and 19 elderly normal (EN) subjects: (a) whether EMD is correlated with delta EEG in baseline sleep; (b) whether EMD is increased by daytime naps; and (c) whether EMD patterns across sleep cycles differ in the two age groups. Subjects participated in four separate 2-day recording sessions, each consisting of a baseline night, a daytime nap, and post nap night. EMD was measured as 0.3-2 Hz integrated amplitude (IA)/20 s stage REM. EMD was not correlated with rate of non rapid eye movement (NREM) delta production (power/min) in the baseline sleep of either group. Changes in EMD and delta power/min on post nap nights also were uncorrelated. These data indicate that very strong changes in sleep depth (state) are required to overcome the individual stability (traits) of NREM delta and eye movement density. ANOVA for EMD across REM periods 1-4 showed a significant cycle effect and a significant age x cycle interaction. These effects were mainly due to YNs having depressed EMD in the first REM period, likely due to the low arousal level early in sleep in these subjects. Compared with waking saccades the saccade eye movements of REM sleep have received little investigation. Further study of these movements could shed new light on neurophysiology of REM sleep. Such studies might also be clinically useful because the density of these movements appears to be related to depression and (independently) to cognitive function in individuals with brain impairment.     

Electroencephalographic sleep in young, never-medicated schizophrenics. A comparison with delusional and nondelusional depressives and with healthy controls

Electroencephalographic (EEG) sleep characteristics of young, never-medicated, nonschizoaffective schizophrenics were compared with the EEG sleep of patients with major depressive disorders (delusional and nondelusional) and with that of healthy controls. Schizophrenics had decreased sleep continuity comparable to delusional depressives. Slow-wave sleep percent was similar to that seen in healthy controls, as was the intranight temporal distribution of EEG delta activity. However, schizophrenics showed diminished delta counts per minute of non-rapid eye movement (NREM) sleep and a decreased total delta wave count. In contrast, depressives showed diminished slow-wave sleep percent compared with controls, greatly decreased delta activity (more so than did the schizophrenics), and an altered temporal distribution of delta activity, as evidenced by a shift of delta activity from the first to the second NREM period. Minutes of slow-wave sleep in the schizophrenics was inversely correlated with the severity of negative symptoms independent of the effects of age and the presence of depression. The schizophrenics showed normal REM latency and first REM period duration, in contrast to the depressives. These findings, reviewed in the historical context of sleep physiologic studies of schizophrenia over the past 30 years, suggest that young, never-medicated schizophrenics do not show the characteristic constellation of abnormalities in the first NREM-REM cycle seen in patients with major depression. However, decreased slow-wave sleep should be investigated as a possible marker for negative symptoms in schizophrenia.     

Internight reliability and benchmark values for computer analyses of non-rapid eye movement (NREM) and REM EEG in normal young adult and elderly subjects.

OBJECTIVE: To determine the reliability of computer measured non-rapid eye movement (NREM) and REM frequency bands in the 0.3-45 Hz range and to provide benchmark data for these measures in young normal (YN) and elderly normal (EN) subjects (Ss). METHODS: Sleep EEG was recorded in 19 YN and 19 EN Ss on 4 non-consecutive baseline nights and simultaneously quantified as fast Fourier transform (FFT) power and 3 zero-cross period-amplitude (PA) measures: integrated amplitude, time in band and average wave amplitude. RESULTS: The shapes of both the FFT and PA spectra differed among Ss but were highly consistent within individuals. Inter-night reliability of the separate frequency bands was correspondingly high. Despite substantial age effects, the reliability of computer-measured sleep EEG in the elderly equaled that of the YN Ss. Within both the YN and EN groups, the shapes of the NREM and REM spectral curves differed significantly. The NREM and REM also differed significantly in the two age groups. CONCLUSIONS: Computer-measured sleep EEG is highly reliable across non-consecutive nights in both young and elderly normal Ss. The trait-like stability of these measures suggests they are genetically determined. This possibility is supported by twin study data that show strong heritability for FFT-measured waking EEG. The different shapes of NREM and REM spectra add further evidence that these are fundamentally different states of brain organization. The age differences in spectral shape, along with PA data for wave incidence, demonstrate that age effects on sleep EEG are not caused by changes in skull impedance or other non-cerebral factors.     

Differences between morning-types and evening-types in the dynamics of EEG slow wave activity during night sleep.

During baseline nights in a sleep laboratory electrophysiological sleep records were made for 8 morning-type subjects (M-types) and 8 evening-type subjects (E-types). As compared with the E-types, the M-types were relatively advanced with respect to the times of maximum and minimum rectal temperature and sleep times. Also, the M-types showed a larger initial temperature drop after sleep onset. Comparisons of the outcomes of visual sleep scoring revealed for the M-types a shorter sleep latency and a longer sleep duration. In addition, the M-types reported a higher subjective sleep quality than the E-types. For the M-types sleep stages 3 + 4 and EEG delta (0.5-3.5 Hz) energy declined monotonically across the first 4 NREM/REM cycles. For the E-types, however, no decrement was observed over the first 2 cycles. Analysis of the wave forms of delta energy, employing a pattern recognition technique independent of visual sleep scoring, substantiated this finding. These results are discussed in relation to the differences in circadian characteristics between M-types and E-types.     

The impact of chronic primary insomnia on the heart rate – EEG variability link

ObjectiveTo determine if chronic insomnia alters the relationship between heart rate variability and delta sleep determined at the EEG.MethodsAfter one night of accommodation, polysomnography was performed in 14 male patients with chronic primary insomnia matched with 14 healthy men. ECG and EEG recordings allowed the determination of High Frequency (HF) power of RR-interval and delta sleep EEG power across the first three Non Rapid Eye Movement (NREM)–REM cycles. Interaction between normalized HF RR-interval variability and normalized delta sleep EEG power was studied by coherency analysis.ResultsPatients showed increased total number of awakenings, longer sleep latency and wake durations and shorter sleep efficiency and REM duration than controls (p < .01). Heart rate variability across first three NREM–REM cycles and sleep stages (NREM, REM and awake) were similar between both groups. In each group, normalized HF variability of RR-interval decreased from NREM to both REM and awake. Patients showed decreased linear relationship between normalized HF RR-interval variability and delta EEG power, expressed by decreased coherence, in comparison to controls (p < .05). Gain and phase shift between these signals were similar between both groups.ConclusionsInteraction between changes in cardiac autonomic activity and delta power is altered in chronic primary insomniac patients, even in the absence of modifications in heart rate variability and cardiovascular diseases.SignificanceThis altered interaction could reflect the first step to cardiovascular disorders.     

Correlation between electroencephalography and heart rate variability during sleep

It is known that autonomic nervous activities change in correspondence with sleep stages. However, the characteristics of continuous fluctuations in nocturnal autonomic nerve tone have not been clarified in detail. The study aimed to determine the possible correlation between the electroencephalogram (EEG) and autonomic nervous activities, and to clarify in detail the nocturnal fluctuations in autonomic nerve activities. Overnight EEGs and electrocardiograms of seven healthy males were obtained. These EEGs were analyzed by fast Fourier transformation algorithm to extract delta, sigma and beta power. Heart rate and heart rate variability (HRV) were calculated in consecutive 5-min epochs. The HRV indices of low frequency (LF), high frequency (HF) and LF/HF ratio were calculated from the spectral analysis of R-R intervals. The sleep stages were manually scored according to Rechtschaffen and Kales' criteria. Low frequency and LF/HF were significantly lower during non-rapid eye movement (NREM) than REM, and were lower in stages 3 and 4 than in stages 1 and 2. Furthermore, delta EEG showed inverse correlations with LF (r = - 0.44, P < 0.001) and LF/HF (r = - 0.41, P < 0.001). In contrast, HF differed neither between REM and NREM nor among NREM sleep stages. Detailed analysis revealed that correlation was evident from the first to third NREM, but not in the fourth and fifth NREM. Delta EEG power showed negative correlations with LF and LF/HF, suggesting that sympathetic nervous activities continuously fluctuate in accordance with sleep deepening and lightening.     

Sleep states and sleep electroencephalographic spectral power in mice lacking the beta 3 subunit of the GABA(A) receptor

Mice lacking the GABA(A) receptor beta(3) subunit exhibit a profound disruption in thalamic circuitry. We have studied sleep in these mice under baseline conditions and following treatment with the benzodiazepine midazolam. Under baseline conditions, NREM sleep time did not differ between beta(3) subunit knockout mice and wild type mice, while REM sleep time was significantly lower in knockout mice than in wild type mice during the light portion of a 24-h light-dark cycle. In constant dark conditions, circadian rhythmicity remained intact in mutant mice for a period of at least 9 days. EEG delta power (1-4 Hz) was significantly greater in the knockout than in wild type mice during NREM sleep but not during other states. A transient increase in EEG power in the 12-16 Hz range that occurred in wild type mice just prior to the transition from NREM to REM sleep was present but significantly blunted in the knockout. Midazolam decreased NREM delta power and REM time in wild type mice. The former but not the latter response to midazolam was intact in the knockout. These results further support a role for GABAergic transmission in regulating REM sleep and EEG spectral phenomena associated with NREM sleep.     

REM sleep EEG spectral analysis in patients with first-episode schizophrenia

The pathophysiology of schizophrenia includes abnormalities in subcortical-cortical transfer of information that can be studied using REM sleep EEG spectral analysis, a measure that reflects spontaneous and endogenous thalamocortical activity. We recorded 10 patients with first-episode schizophrenia and 30 healthy controls for two consecutive nights in a sleep laboratory, using a 10-electrode EEG montage. Sixty seconds of REM sleep EEG without artifact were analyzed using FFT spectral analysis. Absolute and relative spectral amplitudes of five frequency bands (delta, theta, alpha, beta1 and beta2) were extracted and compared between the two groups. Frequency bands with significant differences were correlated with BPRS positive and negative symptoms scores. Patients with schizophrenia showed lower relative alpha and higher relative beta2 spectral amplitudes compared to healthy controls over the averaged total scalp. Analysis using cortical regions showed lower relative alpha over frontal, central and temporal regions and higher relative beta2 over the occipital region. Absolute spectral amplitude was not different between groups for any given EEG band. However, absolute alpha activity correlated negatively with BPRS positive symptoms scores and correlated positively with negative symptoms scores. Since similar results have been reported following EEG spectral analysis during the waking state, we conclude that abnormalities of subcortical-cortical transfer of information in schizophrenia could be generated by mechanisms common to REM sleep and waking.     

Spectral characteristics of sleep EEG in chronic insomnia

To determine whether the spectral characteristics of the sleep electroencephalogram (EEG) of insomniacs differ from that of healthy subjects, we compared in each of the first four non-rapid eye movement (NREM) and rapid eye movement (REM) episodes: (a) the time courses of absolute power, averaged over the subjects in each group, for the delta, theta, alpha, sigma and beta frequency bands; (b) the relationship between these time courses; and (c) the overnight trend of integrated power in each frequency band. The results show that NREM power, for all frequencies below the beta range, has slower rise rates and reaches lower levels in the insomniac group, whereas beta power is significantly increased. In REM, insomniacs show lower levels in the delta and theta bands, whereas power in the faster frequency bands is significantly increased. Thus, the pathophysiology of insomnia is characterized not only by the generally acknowledged slow wave deficiency, but also by an excessive hyperarousal of the central nervous system throughout the night, affecting both REM and NREM sleep. This hyperarousal is interpreted in terms of the neuronal group theory of sleep which provides a possible explanation for the discrepancies observed between subjective impressions and objective measures of sleep. Also, it is suggested that the progressive hyperpolarization of the thalamocortical neurons as sleep deepens is slower in the patient population and that this may explain the observed slow wave deficiency. The homeostatic control of slow wave activity, on the other hand, would appear to be intact in the patient population.     

Sleep and treatment response in depression: new findings using power spectral analysis

This study examined quantitative measures of sleep electroencephalogram (EEG) and phasic rapid eye movements (REM) as correlates of remission and recovery in depressed patients. To address correlates of remission, pre-treatment EEG sleep studies were examined in 130 women outpatients with major depressive disorder treated with interpersonal psychotherapy (IPT). To address correlates of recovery, baseline and post-treatment EEG sleep studies were examined in 23 women who recovered with IPT alone and 23 women who recovered with IPT+fluoxetine. Outcomes included EEG power spectra during non-rapid eye movement (NREM) sleep and REM sleep and quantitative REMs. IPT non-remitters had increased phasic REM compared with remitters, but no significant differences in EEG power spectra. IPT+fluoxetine recoverers, but not IPT recoverers, showed increases in phasic REM and REM percentage from baseline to recovery. In NREM sleep, the IPT+fluoxetine group showed a decrease in alpha power from baseline to recovery, while the IPT group showed a slight increase. The number of REMs was a more robust correlate of remission and recovery than modeled quantitative EEG spectra during NREM or REM sleep. Quantitative REMs may provide a more direct measure of brainstem function and dysfunction during REM sleep than quantitative sleep EEG measures.     

Non-REM sleep instability in patients with major depressive disorder: subjective improvement and improvement of non-REM sleep instability with treatment (Agomelatine)

OBJECTIVE: To assess the importance of non-rapid eye movement (NREM) sleep disturbance in major depressive disorder (MDD) patients using cyclic alternating pattern (CAP) analysis, and to determine the usefulness of CAP analysis in evaluating treatment effect. METHODS: Baseline sleep-staging data and CAP analysis of NREM sleep was compared in 15 MDD patients (Hamilton depression scale score>20) and normal controls. Longitudinal evaluation of sleep changes using similar analysis during a treatment trial was also performed. ANALYSIS: A single-blinded researcher scored and analyzed the sleep of MDD and age-matched normal controls at baseline and during a treatment trial using the international scoring system as well as CAP analysis. RESULTS: MDD patients had evidence of disturbed sleep with both analyses, but CAP analysis revealed more important changes in NREM sleep of MDD patients at baseline than did conventional sleep staging. There was a significant decrease in CAP rate, time, and cycle and disturbances of phase A subtype of CAP. NREM abnormalities, observed by CAP analysis, during the treatment trial paralleled subjective responses. Analysis of subtype A phase of CAP demonstrated better sleep improvement. CONCLUSION: CAP analysis demonstrated the presence of more important NREM sleep disturbances in MDD patients than did conventional sleep staging, suggesting the involvement of slow wave sleep (SWS) in the sleep impairment of MDD patients. Improvement of NREM sleep paralleled subjective mood improvement and preceded REM sleep improvement. CAP analysis allowed objective investigation of the effect of treatment on sleep disturbances.     

Periodic limb movements both in non-REM and REM sleep: Relationships between cerebral and autonomic activities

ObjectiveTo investigate the temporal relationship between cerebral and autonomic activities before and during periodic limb movements in NREM and REM sleep (PLMS).MethodsPatterns of EEG, cardiac and muscle activities associated with PLMS were drawn from polysomnographic recordings of 14 outpatients selected for the presence of PLMS both in NREM and REM sleep. PLMS were scored during all sleep stages from tibial EMG. Data from a bipolar EEG channel were analyzed by wavelet transform. Heart rate (HR) was evaluated from the electrocardiogram. EEG, HR and EMG activations were detected as transient increase of signal parameters and examined by analysis of variance and correlation analysis independently in NREM and REM sleep. Homologous parameters in REM and NREM sleep were compared by paired t-test.ResultsThe autonomic component, expressed by HR increase, took place before the motor phenomenon both in REM and NREM sleep, but it was significantly earlier during NREM. In NREM sleep, PLM onset was heralded by a significant activation of delta-EEG, followed by a progressive increase of all the other bands. No significant activations of delta EEG were found in REM sleep. HR and EEG activations positively correlated with high frequency EEG activations and negatively (in NREM) with slow frequency ones.ConclusionsOur findings suggested a heralding role for delta band only in NREM sleep and for HR during both NREM and REM sleep. Differences in EEG and HR activation between REM and NREM sleep and correlative data suggested a different modulation of the global arousal response.SignificanceIn this study, time–frequency analysis and advanced statistical methods enabled an accurate comparison between brain and autonomic changes associated to PLM in NREM and REM sleep providing indications about interaction between autonomic and slow and fast EEG components of arousal response.