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At least 757 records · Page 42Linked to original sources
PubMed1993

Symposium: Normal and abnormal rem sleep regulation: Episodic hormone release in relation to REM sleep.

Similar periodicities of about 90-100 min characterize both hormone pulsatility and NREM-REM sleep cycles suggesting that both processes could be temporally linked. From the current knowledge of the literature, it appears that, in spite of the diversity of the relationship between hormones and the sleep/wake cycle, systematic relationships exist between hormone pulses and the NREM-REM sleep cycles. Early studies have demonstrated the temporal association between GH and SWS episodes occurring soon after sleep onset. Renin, a key enzyme of the renin-angiotensin system, displays nocturnal oscillations that are associated strongly with the NREM-REM sleep cycles, and represents the first identified biological marker of sleep stage alternation. SWS invariably occurs in the descending phases of TSH and cortisol pulses which suggests that some specific mechanisms of this sleep stage could modulate their levels or, conversely, that increased TSH and cortisol secretion prevents the occurrence of deep sleep. Apart from the period of sleep onset associated with reduced prolactin secretion, no systematic relationship has been found between REM sleep and hormone release. These results highlight the complexity of hormone and sleep interactions and provide a basis for further research into their functional significance.

Journal Article↗
PubMed1995

Symposium: Cognitive processes and sleep disturbances: Sleep, dreams and memory: an overview.

Investigations into the role played by sleep in information processing have consistently shown that the retention of information is better when the memory storage is followed by a period of sleep than of waking. Less definitive evidence, however, is available as to whether the better performance is mainly due to (a) reduction of interference during sleep, (b) slowing down of decay, or (c) consolidation processes at work during sleep. Important insights as to whether consolidation takes place during sleep have recently been provided by the thematic continuity of dreams elaborated in the same night and by the repeated incorporation of pre-sleep stimuli into dream contents. The analysis of such aspects of dreaming indicates that the items of information which are repeatedly accessed during sleep and elaborated for insertion into the ongoing dream experience are better retained at delayed recall. Finally, it is suggested that the use of the strategies applied in studying the information processing in normals may also be extended to sleep-disturbed individuals, in order to establish how memory functioning during sleep is influenced by sleep disturbances.

Journal Article↗
PubMed1995

Respiration in NREM and REM sleep after upper airway surgery for obstructive sleep apnoea.

To verify whether upper airway surgery in obstructive sleep apnoea syndrome affects differently respiration in NREM and REM sleep, 22 patients were studied by polysomnography before and three months after surgical treatment. On the average, treatment improved respiration during both sleep states, but no significant interaction was found between sleep state and effect of surgical treatment. According to the response to treatment, three groups of patients were identified: the first group (N = 6), with an improvement in apnoea-hypopnoea index (AHI), percentage of sleep time spent in apnoea and hypopnoea (time in AH) and mean oxyhaemoglobin saturation (SaO2) in both NREM and REM sleep; the second group (N = 5), with an improvement in AHI only in NREM sleep, associated with improvement in mean SaO2 in both sleep states; the third group (N = 11), without any improvement in AHI and time in AH, either associated (N = 5) or not (N = 6) with an improvement in mean SaO2 in both sleep states. An increase in the percentage of hypopnoeas out of the total AHI after treatment could partly account for the apparent discrepancy between AHI and mean SaO2 behaviour in the subjects of the second group, but not in the patients of the third group who improved their mean SaO2. Mixed apnoeas occurred before surgery in six subjects; they remained numerous after surgery only in two subjects who did not show any SaO2 improvement. In conclusion, the degree of improvement in respiration after upper airway surgery was similar in every patient in NREM and REM sleep.

Journal Article↗
PubMed1982

48-hour sleep-wake cycles in manic-depressive illness: naturalistic observations and sleep deprivation experiments.

Wrist motor activity and sleep were monitored longitudinally in 15 rapidly cycling and 52 nonrapidly cycling manic-depressive patients. The majority of patients experienced one or more consecutive 48-hour sleep-wake cycles (alternate nights with no sleep) when they switched out of depression into mania of hypomania. During a depressive phase, nine rapidly cycling patients were asked to simulate a 48-hour sleep-wake cycle by remaining awake for 40 hours (one night's total sleep deprivation). Eight switched out of depression, and seven were rated as manic or hypomanic; indicating that sleep loss (such as occurs with spontaneous 48-hour sleep-wake cycles) may help to trigger switches from depression to mania. The 48-hour sleep-wake cycles in patients may depend on a mechanism that is normally present in all humans, since normal persons also spontaneously experience near-48 hour sleep-wake cycles in certain experimental conditions.

Adult↗
PubMed2004

Sleep and arousal mechanisms in experimental epilepsy: epileptic components of NREM and antiepileptic components of REM sleep.

Neural generators related to different sleep components have different effects on seizure discharge. These sleep-related systems can provoke seizure discharge propagation during nonrapid eye movement (NREM) sleep and can suppress propagation during REM sleep. Experimental manipulations of discrete physiological components were conducted in feline epilepsy models, mostly in the systemic penicillin epilepsy model of primary generalized epilepsy and the amygdala kindling model of the localization-related seizure disorder, temporal lobe epilepsy. The sleep-wake state distribution of seizures was quantified before and after discrete lesions, systemic and localized drug administration, and/or photic stimulation, as well as in relation to microdialysis of norepinephrine. We found that (1) neural generators of synchronous EEG oscillations--including tonic background slow waves and phasic "arousal" events (sleep EEG transients such as sleep spindles and k-complexes)--combine to promote electrographic seizure propagation during NREM and drowsiness, and antigravity muscle tone permits seizure-related movement; (2) neural generators of asynchronous neuronal discharge patterns reduce electrographic seizures during alert waking and REM sleep, and skeletal motor paralysis blocks seizure-related movement during REM; (3) there are a number of similarities between amygdala-kindled kittens and children with Landau-Kleffner Syndrome (LKS) that suggest a link among seizures, sleep disorders, and behavioral abnormalities/regression.

Amygdala↗
PubMed1990

Sleep, gender, and depression: an analysis of gender effects on the electroencephalographic sleep of 302 depressed outpatients.

Gender-related differences in electroencephalographic (EEG) sleep were examined in 151 pairs of men and women with major depression, all outpatients, matched for age and severity of depression. Across five decades (age 21-69), depressed men had less slow-wave sleep than did depressed women. Gender differences were small with respect to visually scored measures of slow-wave sleep time and percent, but moderate for gender differences in automated measures of slow-wave density. The time constant of the polygraph preamplifier significantly affected both visually scored and automatically scored slow-wave sleep. Other measures such as REM sleep latency, first REM period duration, sleep efficiency, and early morning awakening, showed robust age effects, but no main effects for gender or gender-by-age interactions. Gender effects on slow-wave sleep and delta-wave counts in depression parallel gender effects seen in healthy aging. The possibility of occult alcohol use by depressed male outpatients cannot be definitely excluded as a partial explanation of the current findings. However, covarying for past alcohol abuse did not negate the statistical significance of the observed gender effects on slow-wave sleep and delta-wave density. The possibility of gender differences in slow-wave regulatory mechanisms is suggested, but similarity in temporal distribution of delta-wave density between the first and second non-rapid-eye-movement (NREM) periods does not support gender differences in slow-wave sleep regulation.

Adult↗
PubMed1982

Comparative evaluation of sleep deprivation and sedated sleep EEGs as diagnostic aids in epilepsy.

The comparative value of sedated sleep and sleep deprivation EEGs was investigated in a consecutive series of 43 patients who had received both types of activation study for diagnostic purposes. Patients were referred because of persisting doubt concerning either the diagnosis of epilepsy, or the type of epilepsy present in those with definite seizures. Forty-one had had routine waking EEGs, all of which were normal or only mildly abnormal. EEGs were rated without access to previous reports or clinical data, and epileptiform discharges (ED) were semiquantified during wakefulness and sleep. De novo precipitation of ED, increase in abundance of ED and discovery of a new independent focus or a new type of ED were taken as the yield of useful information. 44% of sleep deprivation records provided useful information compared to 14% of sedated sleep recordings (P less than 0.005). In addition, sleep deprivation was significantly superior to sedated sleep in differentiating those with a final clinical diagnosis of epilepsy from those with doubtful or no epilepsy (P less than 0.001). It is suggested that the usefulness of the interictal EEG in patients with uncertain epilepsy or epilepsy of unknown type is increased by performance of a diagnostic series to include routine waking, sedated sleep and sleep deprivation recordings.

Adolescent↗
PubMed1987

The effect of subcutaneous administration of delta sleep-inducing peptide (DSIP) on some parameters of sleep in the cat.

Delta sleep inducing peptide (DSIP) significantly increases deep-slow-wave sleep (DSWS) of cats after subcutaneous (SC) injection. Cats (n = 8) were SC injected with DSIP (120 nmol.kg-1) prior to polygraphic recording of EEG combined with electro-oculography, EOG) and electromyography (EMG) for 8 hours. DSIP was found to significantly increase slow-waves (delta sleep) in the sleep EEG. There was a tendency to reduced waking time and a prolongation of slow wave sleep time, and a shortening of sleep onset and REM sleep latencies but the differences from control (Ringer injection) were not statistically significant. There was no change in the amount of REM sleep. These findings support the belief that DSIP can increase sleep wave activity when administered by peripheral route.

Animals↗
PubMed1988

The sequential hypothesis on sleep function. II. A correlative study between sleep variables and newly synthesized brain DNA.

The information acquired by brain during wakefulness (W) may be processed in two sequential steps occurring during synchronized sleep (SS) and paradoxical sleep (PS), respectively. On the assumption that brain molecules synthesized during the acquisition step undergo a comparable sleep processing, we have designed an experiment aimed at the verification of the sequential hypothesis. Groups of adult female Wistar rats received [3H-methyl] thymidine by intraventricular injection 30 min before being exposed to a 4 hr session of a two-way active avoidance training. Animals failing to achieve the learning criterion were further allowed a period of 3 hr during which they were left free to sleep, or were deprived of PS or of total sleep. Control rats were similarly treated, but were left in their home cages in the same training room during the period of acquisition. The results of correlative study among behavioral, sleep and biochemical variables demonstrate that the specific radioactivity of DNA in the cerebral cortex, cerebellum and brainstem is correlated with several variables of postacquisition sleep, mostly SS parameters. The correlations depend on the previous waking experience of the rats. The data substantiate the two main consequences of the hypothesis, i.e., (1) the involvement of SS in brain information processing; and (2) the dependence of the operations performed by the sleeping brain on the nature of the previous waking experience. The results also provide some insight into the kind of processing which occurs in the sleeping brain.

Animals↗
PubMed1995

The reticular arousal threshold during the transition from slow wave sleep to paradoxical sleep in the rat.

The short-lasting intermediate stage of sleep occurring between slow wave sleep and paradoxical sleep showed frontal cortex spindles of higher amplitude and longer duration than during slow wave sleep, and hippocampal theta rhythm of lower frequency than during paradoxical sleep. During the intermediate stage, the mesencephalic reticular arousal threshold was slightly higher than during the slow wave sleep and much lower than in the paradoxical sleep. Thus, following this central reactivity test, the intermediate stage seems to be functionally nearer the slow wave sleep than the paradoxical sleep.

Animals↗
PubMed1984

Application of automated REM and slow wave sleep analysis: II. Testing the assumptions of the two-process model of sleep regulation in normal and depressed subjects.

Abnormalities in a two-process model of sleep regulation (a sleep-dependent process, termed Process S, and a sleep-independent circadian process, termed Process C) have been proposed to account for sleep abnormalities in depressive states. The major tenets of the two-process model of sleep regulation as applied to depression are: the level of process S, as reflected by the electroencephalographic (EEG) slow-wave activity, corresponds to the sleep-dependent facet of sleep propensity; the pathognomonic changes of sleep in depressives are a consequence of a deficiency in the build-up of process S. The application of automated rapid eye movement (REM) and delta wave analyses in normal subjects and younger depressed patients supports the model to some extent: The time spent asleep is positively correlated with total delta waves (normals and depressives) and average delta waves (depressives); delta sleep is lower in depressives than in normals; the average delta wave count is significantly reduced in younger depressives over the total night and in non-REM period 1. The model also postulates that measures of phasic REM activity are inversely related to process S, suggesting that process S can be regarded as exerting an inhibitory influence on phasic REM activity.

Adult↗
PubMed1996

[Propensity for sleep and diurnal somnolence in the course of sleep apnea syndrome].

Daytime sleepiness is one of the major symptoms of obstructive sleep apnea. However, its definition raises problems, since it may be based on either subjective feeling (evaluated by means of questionnaires or analog visual scales), physiological drive or need (inferred by a sleep latency) or on the concept of sleep propensity defined as the probability of falling asleep (measured by the occurrence of sleep in various circumstances of daily life). Data from the literature suggest that sleep fragmentation and hypoxemia, both related to sleep apneas, cause daytime sleepiness. Our own data show that sleep propensity in a group of 44 patients with obstructive sleep apnea was correlated with the increase in esophageal pressure swings during obstructive apneas. This result suggests that the increased respiratory effort against occluded upper airways also contributes to daytime sleepiness in patients with obstructive sleep apnea.

Circadian Rhythm↗
PubMed2005

Sleep-wake behavior and responses of interleukin-6-deficient mice to sleep deprivation.

Interleukin (IL)-1 and tumor necrosis factor (TNF) are involved in the regulation of non-rapid eye movements sleep (NREMS). Accumulating evidence suggests IL-6 modulates sleep under some pathophysiologic conditions. We used mice lacking a functional IL-6 gene to investigate further a potential role for IL-6 in the regulation of sleep. IL-6 knockout mice (B6.129S6-Il6tm1Kopf; n=10) and C57BL/6J mice (n=10) were purchased from the Jackson Laboratory (Bar Harbor, ME). Twenty-four-hour baseline recordings were obtained from mice in the absence of any experimental manipulation. Mice were then subjected to 6-h sleep deprivation beginning at light onset. Recordings were obtained during the deprivation period and for 18 h thereafter. During baseline conditions there were no differences between mouse strains with respect to the duration, timing or intensity of NREMS. However, across the 24-h recording period IL-6 knockout mice spent approximately 30% more time in rapid eye movements sleep (REMS) than did C57BL/6J mice. Relative to C57BL/6J mice, core body temperatures of IL-6 knockout mice were higher during the light period of the light:dark cycle. Both strains responded to sleep deprivation by spending more time in NREMS and REMS. Although the total increase in the amount of NREMS after sleep deprivation was the same in both strains, IL-6 knockout mice took 6h longer to accumulate this additional sleep. Under the conditions of this study, IL-6 does not appear necessary for the full manifestation of NREMS, although this cytokine may influence the dynamics of responses to sleep deprivation. That mice lacking IL-6 spend more time in REMS suggests that interactions between IL-6 and REMS regulatory mechanisms may differ from those of IL-1 and/or TNF.

Animals↗
PubMed2006

Gene expression in the rat cerebral cortex: comparison of recovery sleep and hypnotic-induced sleep.

Most hypnotic medications currently on the market target some aspect of GABAergic neurotransmission. Although all such compounds increase sleep, these drugs differentially affect the activity of the cerebral cortex as measured by the electroencephalogram. Whereas benzodiazepine medications such as triazolam tend to suppress slow wave activity in the cortex, the GABA(B) ligand gamma-hydroxybutyrate greatly enhances slow wave activity and the non-benzodiazepine, zolpidem, which binds to the omega1 site on the GABA(A) receptor/Cl(-) ionophore complex, is intermediate in this regard. Our previous studies have demonstrated that a small number of genes exhibit increased expression in the cerebral cortex of the mouse and rat during recovery sleep after sleep deprivation: egr-3, fra-2, grp78, grp94, ngfi-b, and nr4a3. Using these genes as a panel of biomarkers associated with sleep, we asked whether hypnotic medications induce similar molecular changes in the rat cerebral cortex to those observed when both sleep continuity and slow wave activity are enhanced during recovery sleep. We find that, although each drug increases the expression of a subset of genes in the panel of biomarkers, no drug fully replicates the molecular changes in the cortex associated with recovery sleep. Furthermore, high levels of slow wave activity in the cortex are correlated with increased expression of fra-2 whereas the expression of grp94 is correlated with body temperature. These results demonstrate that sleep-related changes in gene expression may be affected by physiological covariates of sleep and wakefulness rather than by vigilance state per se.

Analysis of Variance↗
PubMed2004

An alternative measure of sleep fragmentation in clinical practice: the sleep fragmentation index.

BACKGROUND AND PURPOSE: Micro-arousals (MA) are commonly considered as sleep components reflecting sleep fragmentation. However, their elucidation is time-consuming, with considerable inter-observer variability. The aim of our study was to investigate the usefulness of a sleep fragmentation index (SFI) to detect sleep disruption in a large sample of patients. PATIENTS AND METHODS: Five-hundred ninety-eight polysomnographic studies made in controls and patients were examined. The SFI was calculated as the total number of awakenings and sleep stage shifts divided by total sleep time. RESULTS: In the whole group a significant correlation was found between the SFI and the MA index (MAI) (P<0.001) with good agreement across a wide range of values. When patients were stratified according to final diagnosis a significant relation was noted for patients with insomnia (P<0.001), parasomnia (P<0.001), circadian schedule disorders (P<0.001) and sleep related breathing disorders (P< 0.001). Lower values were found in controls (P<0.01) and in patients with periodic limb movement disorder and/or restless legs syndrome (P<0.05). In 111 patients having two consecutive recording nights, a good reproducibility was present with no differences between nights (P=ns) and with significant correlation (P<0.001). CONCLUSIONS: The SFI seems to be an accurate, reproducible and easy method to detect sleep fragmentation in patients with sleep disorders. Further studies are needed to validate the usefulness of this tool in clinical practice.

Adult↗
PubMed2000

Sleep bruxism in patients with sleep-disordered breathing.

The aim was to test the hypothesis of a direct association between sleep-disordered breathing and sleep bruxism. The frequency of masseter contraction (MC) episodes and rhythmic jaw movements (RJM) was measured in patients with mild and moderate obstructive sleep apnoea (OSA). The diagnosis of sleep bruxism was made from a combination of questionnaire, clinical observation and all-night polysomnographic recording which included masseter electromyography. A total of 21 patients (19 males/two females, mean age 40.0 years+/-9.2 SD) were randomly selected from a provisional diagnosis of snoring and OSA by a sleep physician. In the patients with mild OSA [n=11, mean apnoea hypopnoea index (AHI)=8.0+/-4.1 SD, body mass index (BMI)=29.1+/-5.0], the diagnosis of sleep bruxism was made in six out of 11 patients (54%); similarly, four out of 10 patients (40%) with moderate OSA (n=10, mean AHI=34.7+/-19.1, BMI=30.6+/-5.0) were identified as bruxists. Although the combination of clinical, subjective estimation and nocturnal electromyographic recording of masseter muscle might provide a more solid base for the diagnosis of sleep bruxism, the result is biased by the variation in the bruxing activity. MC episodes were associated with the termination of apnoea or hypopnoea episodes in only 3.5% of the mild group and 14.4% of the moderate group (p<0.05). It appears that sleep bruxism is rarely directly associated with apnoeic events, but is rather related to the disturbed sleep of OSA patients.

Adult↗
PubMed1999

Mandibular posture during sleep in patients with obstructive sleep apnoea.

Vertical mandibular posture is thought to be related to narrowing of the upper airway, because mouth opening is associated with an inferior-posterior movement of the mandible and the tongue which influences pharyngeal airway patency. To test whether the mandibular posture is related to the occurrence and/or termination of obstructive sleep apnoea (OSA), the vertical mandibular position was recorded intraorally using a magnet sensor during a standard sleep study in seven patients with OSA. Measurements were recorded during sleep both in the supine and lateral recumbent positions. The percentage of total sleep time spent with mandibular opening greater than 5 mm was significantly larger (p<0.001) in patients with OSA (69.3+/-23.3%) compared with our previous results obtained from healthy adults without OSA (11.1+/-11.6%). The stage of sleep affected the vertical mandibular posture during sleep in the supine position, but not in the lateral recumbent position in patients with OSA. In non-rapid eye-movement sleep, mandibular opening increased progressively during apnoeic episodes and decreased at the termination of apnoeic episodes. In contrast, no significant change in mandibular posture occurred in apnoeic episodes during rapid eye-movement sleep. It was concluded that the vertical mandibular posture is more open during sleep in patients with OSA than in healthy adults and that mandibular opening increases progressively during apnoeic episodes and decreases at the termination of those episodes.

Analysis of Variance↗
PubMed1997

REM sleep disinhibition at sleep onset: a comparison between narcolepsy and depression.

Shortened REM latency and increased REM density are frequently observed in both narcolepsy and depression, suggesting a common mechanism of REM sleep disinhibition in these disorders. We compared night sleep recordings of 24 depressive and 24 narcoleptic patients. The amount of REM sleep and REM density did not differ between the patient groups; however, REM latency distributions differed significantly. Whereas in narcoleptic patients REM episodes started either immediately at sleep onset or following at least 60 min of non-REM sleep, in depressives two thirds of REM latencies were in the range from 1 to 60 min. In narcoleptic patients, short as compared to long REM latencies were associated with longer total sleep time, greater sleep efficiency, reduced amounts of wakefulness, and increased amounts of slow-wave sleep. In depressive subjects the reverse pattern was seen. We conclude that a common mechanism of REM sleep disinhibition in narcolepsy and depression is very unlikely.

Adult↗