bluuebunny/crossref_metadata_2025 huggingface dataset:
The severity of obstructive sleep apnoea is associated with insulin resistance
Authors: TIIHONEN MIKKO , PARTINEN MARKKU , NÄRVÄNEN SAKARI
Published: January 2009

SUMMARY  Oral glucose tolerance tests (OGTT) were performed on eighteen patients with suspected obstructive sleep apnoea who also completed a whole‐night polygraphic recording with oximetry. Insulin resistance indices (IRI) were calculated as the product of areas under glucose and insulin curves. In the resulting multiple regression analysis the dependent variable was IRI and the independent variables were age, body mass index (BMI) and the number of nocturnal hypoxic episodes with over 4% desaturation per hour (ODI4).

ODI4 was between 4.6 and 70 (median 22.3); IRI ranged from 2.20 to 33.55 (median 7.50). In the regression model the coefficient of determination (R2) for IRI was 0.441 (F‐ratio = 3.681, P= 0.038). The strongest determinant of IRI was ODI4 and the regression coefficient of BMI was not significantly different from zero even when possible outliers were excluded.

It was found that insulin resistance is related to the severity of sleep anoea. This may be due to a hypoxia‐induced hormonal stress reaction which decreases tissue insulin sensitivity. Since upper body obesity is associated with both insulin resistance and sleep apnoea, the distribution of fat should be taken into account in future studies.
Re‐examination of the effects of raphe lesions on the sleep/wakefulness cycle states in cats
Authors: ARPA JAVIER , DE ANDRÉS ISABEL
Published: January 2009

SUMMARY  To study the specific effects of central superior raphe nucleus (CeSR) lesions on the different sleep/wakefulness cycle states of the cat, nine animals with implanted electrodes for EOG, EMG and EEG recordings were used. Seven cats received diathermocoagulation lesions that destroyed between 13 and 100 percent of the CeSR; the remaining two cats, which suffered lesions in the paramedial region of the oral pontine reticular nucleus (RPO), were used to determine the effects on sleep/wakefulness states caused by damage to adjacent CeSR structures and/or passage fibres. Three prelesion and five postlesion weekly 24h recordings were obtained from each cat. Recordings were scored according to the polygraphic criteria for wakefulness (W), drowsiness (D), slow wave sleep (SWS) and paradoxical sleep (PS). Results indicated that insomnia is not produced exclusively by CeSR lesions, since adjacent paramedial RPO lesions also decrease both SWS and PS; however, increased W occurred after the former while increased D occurred after the latter. Correlation coefficient analyses showed that W is the only state that correlates significantly with the volume of CeSR destroyed. The following correlations between different states of the sleep/wakefulness cycle were, however, significant: W‐D, W‐SWS and SWS‐PS. Disinhibition of W, therefore, and not sleep loss seems to be the primary effect of CeSR lesions. Thus, the CeSR nucleus appears to be involved in arousal mechanisms rather than in direct sleep promotion.
A sleep disturbance in high risk for SIDS infants
Authors: CORNWELL ANNE CHRISTAKE , LAXMINARAYAN SWAMY
Published: January 2009

SUMMARY  A developmentally immature sleep pattern has been identified in infants with a recent history of an unexplained life‐threatening episode of sleep apnoea who are considered at risk for SIDS. In these infants there is a persistence of Sleep Onset REM Periods (SOREMPS) after prolonged wakefulness when compared to controls matched for age, sex, birthweight and race. This sleep characteristic has not been previously reported.
Body temperature is elevated during the rebound of slow‐wave sleep following 40–h of sleep deprivation on a constant routine
Authors: DIJK DERK‐JAN , CZEISLER CHARLES A.
Published: January 2009

SUMMARY  EEG, EMG, EOG and core body temperature were recorded during baseline sleep and during recovery sleep from a 40–h constant routine in 9 male subjects. Slow‐wave sleep and slow‐wave activity (SWA, EEG power density 0.75–4.5 Hz) were enhanced in the first two nonREM sleep episodes of recovery sleep. Core body temperature was not significantly different in the last 30 minutes before lights out but was significantly higher during recovery sleep in the interval between lights out and sleep onset and during the first nonREM sleep episode. The data demonstrate that an enhancement of SWA/SWS is not necessarily accompanied by lower values of core body temperature, and therefore challenge the notion that SWS is the primary factor responsible for the steep decline of body temperature that occurs at the onset of the nightly sleep episode.
Cluster arousal analysis in chronic pain‐disturbed sleep
Authors: STAEDT JÜRGEN , WINDT HEIKO , HAJAK GÖRAN , STOPPE GABRIELA , RUDOLPH GERHARD , ENSINK FRANZ B. M. , HILDEBRANDT JAN , RÜTHER ECKART
Published: January 2009

SUMMARY  A new cluster arousal analysis system was developed to quantify microdisturbances in the sleep architecture. The system was evaluated in 10 healthy volunteers and the sleep of 23 outpatients with chronic low back pain was investigated before and after a special rehabilitative training. The comparison of sleep parameters before and after the treatment showed a significant reduction of the cluster disturbed sleep (CDS), whereas sleep efficiency and the number of stage shifts remained unchanged. The reduction of the CDS correlated with a reduction of depression scale. This cluster arousal analysis appears to be a sensitive tool for evaluating alterations in the sleep microstructure.
REM sleep in successful, usual, and pathological aging: the Pittsburgh experience 1980–1993
Authors: REYNOLDS CHARLES F. , HOCH CAROLYN C. , BUYSSE DANIEL J. , MONK TIMOTHY H. , HOUCK PATRICIA R. , KUPFER DAVID J.
Published: January 2009

SUMMARY  Successful psychological and physical adaptation in late life correlates with preservation of sleep quality and physiological integrity of nocturnal EEG sleep measures. Failure to adapt is associated with loss of sleep continuity, alterations in the temporal distribution of delta wave activity, and by either a relative increase in REM sleep (e.g. in mood disorders) or a decrease in REM sleep (e.g. neurodegenerative disorders). Maintenance of sleep (particularly REM sleep) into late life may not be just a correlate, but also possibly a mechanism, of successful aging and thus necessary to the long‐term maintenance of vitality and engagement in life.
Phasic muscle activity during REM sleep in infancy—normal maturation and contrastive abnormality in SIDS/ALTE and West syndrome
Authors: KOHYAMA JUN , SHIMOHIRA MASAYUKI , ITOH MASAHIRO , FUKUMIZU MICHIO , IWAKAWA YOSHIHIDE
Published: January 2009

SUMMARY  The generation of phasic muscle activity during REM sleep is regulated by the brainstem. We proposed two sleep indices for phasic muscle activity during REM sleep, and examine their usefulness in assessing normal brainstem maturation and functional brainstem impairment during infancy. One ‐ the dissociation index (DI) ‐ seems to reflect maturation of the tonic inhibitory system functioning during REM sleep, and the other ‐ % body movements in REMs bursts (%BMs‐R) ‐ to reflect that of the phasic one. In normal infants, DI showed a gradual, linear and significant increase with age, whereas %BMs‐R showed a gradual and significant decrease with age. In infants with sudden infant death syndrome (SIDS) and one who had experienced apparent life‐threatening events (ALTE), the DI values were lower than those in controls, although %BMs‐R values were identical in the controls. In contrast, DI was variable in infants with West syndrome (WS), while %BMs‐R exceeded normal values. The tonic inhibitory system seemed to be specifically involved in SIDS and ALTE, but the phasic inhibitory one in WS. Anatomical differences between these inhibitory systems are also discussed.
The value of one hour daytime sleep recording in the diagnosis of the sleep apnoea syndrome
Authors: VAN KEIMPEMA ANTON R. J. , RUTGERS STEVEN R. , STRIJERS ROB L. M.
Published: January 2009

SUMMARY  In this study we investigated whether the diagnosis of sleep apnoea syndrome (SAS), based on night‐time polysomnography (NPSG), can be predicted or excluded by a one‐hour daytime polysomnography (DPSG). The results of 306 NPSGs were compared with DPSGs, which were performed the day before. Treated patients were excluded. In the 89 patients with SAS (Apnoea index (AI)≥5) 59 showed apnoeas during the DPSG and 30 did not. In the 217 without SAS 25 showed apnoeas during DPSG and 192 did not. Sensitivity for detecting SAS was 66%, the specificity was 88%, the positive predictive value (PPV) 70% and the negative predictive value (NPV) 86%. For relevant SAS (AI ≥ 10) the NPV would be 95%. We conclude that the one‐hour DPSG is not sufficient for diagnosing or excluding SAS with certainty. It can be used to make the presence of relevant SAS unlikely.
Hypnotic drugs, psychomotor performance and ageing
Authors: MORGAN KEVIN
Published: January 2009

SUMMARY This review examines studies, reported since 1976, in which the residual effects of hypnotic drugs on psychomotor performance have been evaluated in older people. The 33 studies involved a total of 934 subjects (aged 60–96 y), evaluated 21 different products, utilized 26 test procedures, and reported 169 drug versus placebo (or drug versus drug) comparisons, of which 42 were associated with significant residual impairment. While performance decrements were more associated with longer half‐life drugs, repeated dosing, and frailty, these characteristics were often unreliable in predicting outcome. Significant improvements in performance were rare, and usually consistent with practice effects. While this literature provides a useful basis for clinical caution, it is not characterized by experimental rigour, and provides little or no empirical basis for predicting those real‐life skills most likely to be affected. Issues of subject selection, experimental design, testing strategies, and data analysis need to be addressed if the risks and benefits of hypnotic drug use in later life are to be more clearly understood.
The Ullanlinna Narcolepsy Scale: validation of a measure of symptoms in the narcoleptic syndrome
Authors: HUBLIN C. , KAPRIO J. , PARTINEN M. , KOSKENVUO M. , HEIKKILÄ K.
Published: January 2009

SUMMARY  The Ullanlinna Narcolepsy Scale (UNS) is a simple questionnaire‐based method used to measure the symptoms of the narcoleptic syndrome. The 11‐item scale (range 0–44) assesses the two main features of the narcoleptic syndrome, the abnormal sleeping tendency and cataplexy. The UNS sum score reliably distinguishes patients with the narcoleptic syndrome from patients with sleep apnoea, multiple sclerosis, and epilepsy. The mean score in patients with the narcoleptic syndrome was 27.3 (95% confidence limits 24.4–33.1); the sleep apnoea group with a mean score of 9.6 (95% confidence limits 7.2–12.0) came closest to this. Validation data were also selected from a large survey of non‐institutionalized adults in Finland including groups with insomnia, excessive daytime sleepiness, sleep deprivation, sciatica, alcohol abuse, and high scores on a depression scale and on a scale of neurovegetative symptoms. With the lowest UNS score in the narcoleptic syndrome group (= 14) as the cutpoint, the sensitivity is 100% and the specificity is 98.8% in the subjects studied. The accurate assessment of the symptoms of the narcoleptic syndrome in a format suitable for questionnaire studies is essential.
Effects of rate of tone‐pip stimulation on the evoked K‐Complex
Authors: BASTIEN CÉLYNE , CAMPBELL KENNETH
Published: January 2009

SUMMARY  The effects of rate of presentation on the evoked K‐Complex were examined. In different conditions, brief duration tone pips were presented every 5, 10 or 30 s. Trials were sorted into those on which a K‐Complex was or was not elicited and averaged separately. The evoked K‐Complex consisted of two different negative components peaking at approximately 350 and 550 ms (respectively), followed by a positive component peaking at approximately 900 ms. K‐Complexes were elicited more often in Stage 2 early and 2 late than in slow‐wave sleep although the differences were not significant. K‐Complexes were elicited more often in the Long ISI compared to the Short and Medium ISI conditions. When a K‐Complex was evoked, the amplitude of N350 and N550 was greater for the Long ISI than for the Short or Medium ISI conditions. P900 amplitude remained invariant regardless of the ISI. A micro‐analysis was carried out whenever 3 consecutive occurring K‐Complexes were elicited. During the Short and Medium ISI conditions, N350 and N550 following the second and third occurrence of the K‐Complex were significantly attenuated compared to the first occurrence. There was no difference in N350 and N550 amplitudes among the 3 consecutive occurrences during the Long ISI condition. The decay in amplitude over consecutive occurrences of the K‐Complex might be a reflection of either habituation or refractory processes.
Effects of the selective 5‐HT1Bagonist, CGS 12066B, on sleep/waking stages and EEG power spectrum in rats
Authors: BJORVATN BJØRN , URSIN REIDUN
Published: January 2009

SUMMARY Sleep/waking stages and EEG power spectra were studied in rats for 8 h following intraperitoneal administration of CGS 12066B, a selective 5‐HT1Bagonist. Waking was increased and rapid eye movement (REM) sleep decreased in a dose‐dependent manner. Total slow‐wave sleep (TSWS) was reduced, but only in the first 2 h period. The latencies to REM sleep and stable sleep were increased dose‐dependently. The drug also induced profound behavioural changes that may account for some of the sleep/waking changes. EEG power densities in waking and TSWS were reduced dose‐dependently from 7 to 20 Hz after CGS 12066B, suggesting a tendency towards general deactivation. The increase in waking together with a general deactivation suggest complex effects of CGS 12066B on the sleep/waking axis.
The meaning of good sleep: a longitudinal study of polysomnography and subjective sleep quality
Authors: ÅKERSTEDT TORBJÖRN , HUME KEN , MINORS DAVID , WATERHOUSE JIM
Published: January 2009

SUMMARY  The present study sought to investigate the meaning of subjectively good sleep, using a longitudinal and intraindividual design. Eight subjects slept in an isolation unit according to an irregular schedule of 6h sleeps and 1h naps, designed to give normal amounts of time in bed (1/3 of total), but variable sleep quality. Eight sleeps and eight naps were used for longitudinal simple and multiple regression analyses with standard polysomnographical sleep variables as predictors and subjective sleep quality as dependent variables. The results showed that subjective sleep quality (and related variables) was closely related to sleep efficiency, but not sleep stages. At least 87% efficiency was required for ratings of ‘rather good’ sleep. In addition, sleep quality ratings improved with closeness (of the awakening) to the circadian acrophase (17.00–21.00 hours) of the rectal temperature rhythm. The subjective ease of awakening differed from most other other variables in that it was related to low sleep efficiency. Objective and subjective homologues of sleep length and sleep latency showed high mean intraindividual correlations (r= 0.55 and 0.64, respectively). It was concluded that objective measures of sleep continuity were closely reflected in perceived sleep quality and that sleep quality essentially means sleep continuity.
Premature infants in car seats: effect of sleep state on breathing
Authors: HERTZ GILA , AGGARWAL RENU , ROSENFELD WARREN N. , GREENSHER JOSEPH
Published: January 2009

SUMMARY  Previous studies have shown that premature infants may be at risk for hypoxemia and bradycardia when placed in standard car seats. However, the relationship of such breathing abnormalities to sleep state have not been studied. The purpose of the present study was to investigate the effect of car seat positioning on respiratory patterns in preterm infants during sleep and to evaluate their relationship to sleep state. Complete polysomnography, including sleep and breathing parameters, was performed on twenty‐eight premature infants. Each infant was randomly assigned to the car seat or prone (crib) position for the first recording period. Following the recording of at least two sleep cycles, the position was reversed. The percentage of active and quiet sleep was calculated and breathing parameters were measured. In the car seat, the infants spent significantly more time in active sleep and less time in quiet sleep than in the prone position, of the respiratory parameters, periodic breathing (PB) was significantly higher in the car seat. The presence of at least one abnormal breathing events (bradycardia, desaturation, PB apnoea) was also significantly higher in the car seat. An analysis of variance (ANOVA) of PB revealed significant sleep‐state effect (active vs. quiet sleep), but no significant condition or interaction effects, indicating that PB was more frequent in active sleep regardless of the sleeping condition. It is concluded that increased active sleep in the car seat condition, rather than the positioning of the infant in the seat per se, may account for the increase in periodic breathing and possibly other breathing abnormalities reported in car seats.
Quantitative description of EEG periodicities during stationary sleep stages
Authors: BARCARO UMBERTO , BIZZARI MAURA , NAVONA CARLO , BONANNI ENRICA , MURRI LUIGI
Published: January 2009

SUMMARY  A quantitative method was applied in order to assess variations in EEG activities during sleep. Three classes of variations were distinguished: variations connected with sleep‐stage changes (class 1), higher‐frequency variations described by the envelope of frequency‐band activities (class 2), intermediate‐frequency variations, corresponding to periods from 4 to 120 s (class 3). For each class, parameters characterizing the frequency spectra were computed. These parameters were mathematically simple and clear in their meaning, since they measured power, modulation index and mean squared frequency. A statistical comparison of the mean values of the parameters during different sleep stages evidenced a certain number of significant shifts in each of the three classes. The most important class‐1 and class‐2 variations were described by our parameters with high levels of significance. The results obtained for class 3 were in agreement with visual observations reported in the literature, such as the progressive increase in the interval between successive arousals from sleep onset to Stage 4 and the frequent occurrence of cyclic alternating patterns during Stage 2 epochs immediately preceding REM sleep.
Changes of sleep EEG slow‐wave activity in response to sleep manipulations: to what extent are they related to changes in REM sleep latency?
Authors: BEERSMA D. G. M. , ACHERMANN P.
Published: January 2009

SUMMARY  Sleep interventions may have direct effects on slow‐wave activity (SWA, i.e. power of the sleep EEG signal in the 0.75‐4.5 Hz range) as well as indirect ones caused by changes in REM sleep (REMS) latency. The effects of changes in REMS latency on SWA were investigated by analysing simulations with a mathematical model. Mean SWA in the first non‐REMS episode shows an initial increase and a later decline as a function of REMS latency. In the second non‐REMS episode, mean SWA decreases with increasing REMS latency. These results of the simulations were validated with experimental data.

In the evaluation of the effects of sleep interventions on SWA the effects of the timing of REMS have to be accounted for. The analysis of SWA over a sufficiently long constant amount of time spent in non‐REMS proves to be relatively independent of REMS latency, which allows conclusions about the effects of sleep interventions on SWA per se.
Synchronized sleep duration is related to tonic vasoconstriction of thermoregulatory exchangers
Authors: AZZARONI ADELE , PARMEGGIANI PIER LUIGI
Published: January 2009

SUMMARY  The relationship between duration of the ultradian sleep cycle and intensity of tonic vasoconstrictor sympathetic outflow to thermoregulatory heat exchangers was studied in cats chronically implanted with EEG and EMG electrodes, and temperature transducers. Vasoconstrictor sympathetic outflow to heat exchangers was indirectly appraised by measuring the difference between hypothalamic temperature and ear pinna temperature. The vasoconstrictor sympathetic outflow was varied experimentally by means of thermal and vascular manipulations. The results show that the duration of the stage of synchronized sleep, but not that of the stage of desynchronized sleep of the ultradian sleep cycle, is correlated positively with the intensity of tonic vasoconstrictor sympathetic outflow to heat exchangers in the thermal zone of vasomotor regulation of body temperature.
Prolactin secretion during sleep in obstructive sleep apnoea patients
Authors: SPIEGEL K. , FOLLENIUS M. , KRIEGER J. , SFORZA E. , BRANDENBERGER G.
Published: January 2009

SUMMARY  Plasma prolactin (PRL) concentration exhibits a sleep‐dependent pattern, with highest levels during sleep and lowest levels during the waking period. The syndrome of obstructive sleep apnoea (OSA) is associated with severe hypoxaemia and chronic sleep fragmentation, both of which could affect the sleep‐entrained PRL rhythm. Treatment with nasal continuous positive airway pressure (CPAP) immediately restores a normal sleep structure by successful abolition of the apnoeas. In the present study, seven OSA patients underwent two night studies, once when no treatment was given and once during the first night of CPAP treatment. Sleep was recorded polygraphically in all experiments. Plasma PRL was measured at 10 min intervals and secretory rates were calculated by a deconvolution procedure. CPAP treatment greatly reduced hypoxaemia and improved sleep quality. The secretory pulse amplitude and the total amount of PRL secreted during the night remained constant regardless of whether patients were treated or not. The only difference found was a lower pulse frequency in untreated OSA patients as compared to treated patients, which may be attributed either to hypoxaemia or to sleep disturbance or to the combined action of both. Treatment may be considered to normalize PRL release by restoring pulse frequency to values similar to those observed for normal subjects.
Automatic recognition of rapid eye movement (REM) sleep by artificial neural networks
Authors: Grözinger Michael , Röschke Joachim , Klöppel Bert
Published: January 2009

Artificial neural networks are well known for their good performance in pattern recognition. Their suitability for detecting REM sleep periods on the basis of preprocessed EEG data in humans under clinical conditions was tested and their performance compared with the manual evaluation. A single channel of the EEG signal was analysed in time periods of 20 s and preprocessed into a vector of six real numbers, which served as input to the network. EOG and EMG information was ignored. Backpropagation was used as a learning rule for the network, which consisted of 12 neurons and 39 synapses. Training datasets were put together from the input vectors and the corresponding sleep stages were scored manually. In working mode different networks were compared in terms of the rate of misclassified time periods for data not belonging to the training sets. The indicator function of REM sleep was well approximated by the network output in the course of the night, which was especially true for REM onsets. The average rate of correctly classified time periods was 89%. The errors were analysed and suggestions for improvements developed.
Sleep deprivation and c‐fos expression in the rat brain
Authors: Cirelli Chiara , Pompeiano Maria , Tononi Giulio
Published: January 2009

This study examined the effects of sleep deprivation on the expression of the immediate early gene c‐fos in the brain with both in situ hybridization and immunocytochemistry. Rats were manually sleep‐derived for 3 h, 6 h, 12 h, and 24 h starting at light onset (08.00 hours), and for 12 h starting at dark onset (20.00 hours). c‐Fos expression was found to be higher in sleep‐deprived rats with respect to control animals in several brain areas. The increase was evident both in terms of c‐fos mRNA and Fos protein, although with a different time course. Among the areas that showed a consistent induction of c‐fos were many cortical regions, the medial preoptic area and the posterior hypothalamic area, some thalamic nuclei, and several nuclei of the dorsal pontine tegmentum. The pattern of c‐fos expression after sleep deprivation was very similar to that observed after comparable periods of spontaneous wakefulness (Pompeiano et al. 1994). In general, the increase in c‐fos expression was not simply proportional to the amount of previous wakefulness. In many areas, the highest levels of c‐fos were seen after 3 h of sleep deprivation. These observations are discussed with respect to the homeostatic regulation of sleep and to the functional consequences of wakefulness in specific brain areas.
EEG arousal pattern in habitual snorers with and without obstructive sleep apnoea (OSA)
Authors: Zucconi Marco , Oldani Alessandro , Ferini‐Strambi Luigi , Calori Giliola , Castronovo Cinzia , Smirne Salvatore
Published: January 2009

This study evaluated the arousal pattern and sleep fragmentation in the sleep microstructure of heavy snorers and obstructive sleep apnoea (OSA) patients. Fifteen snorers [Group A, (A + H I) ≤ 10], 15 mild OSA (Group B, A + H I > 10 ≤ 30] and 15 moderate to severe OSA (Group C, A + H I > 30) were studied retrospectively analysing the number, duration and type of arousals according to scoring rules concerning definition (including delta bursts) and length (from 2 to 60 s) of phasic arousal events. The number of arousals per hour of sleep related to respiratory events was higher in Groups B and C, whilst in Group A there was a number of arousals not related to apnoea or hypopnoea. Daytime sleepiness, present in all three groups and measured by a subjective evaluation, correlated with both the number and EEG type of arousal, but not with the duration. Statistical analysis indicated that arousal index related to apnoea or hypopnoea was the best variable for determining the sleepiness risk in OSA and snorers. Sleep microstructure analysis seems a good scoring method for the detection of sleep fragmentation and arousals in relation to abnormal respiratory events.
A reconceptualization of EEG alpha activity as an index of arousal during sleep: all alpha activity is not equal
Authors: PIVIK R. T. , HARMAN K.
Published: January 2009

SUMMARY  Alpha activity occurring during sleep is generally considered to reflect arousal processes and a shift toward wakefulness. This long‐standing interpretation is based on physiological and behavioural arousal correlates of alpha activity presumed to have an occipital focus. In addition to the application of this interpretation to sleep/wake state determinations, there have been reports of nonrefreshing or nonrestorative sleep in clinical populations exhibiting dramatic amounts of alpha intrusion during sleep in the absence of awakening. Reports of the presence of alpha activity during sleep in normal subjects without sleep disruption or complaints of daytime sleepiness call into question the interpretation that this activity is associated with arousal. A re‐examination of this literature, incorporating the results from recent investigations employing multi‐site EEG recordings, electronic processing and source diple analyses of this activity, suggests the existence of alpha activity which differs in generation site (thalamus), scalp distribution (frontal‐central), and behavioural correlates (e.g. enhancement to stimulation during wakefulness, concentration in the first‐half of the night during sleep, and absence of sleep disturbance) from occipital alpha activity. Such marked differences in defining characteristics imply different functional correlates for these activities. In this context, it is proposed that this fronto‐central alpha activity is associated with sleep‐maintaining processes which may be enhanced in response to sleep‐disturbing events.
Diurnal sleep/wake‐related immune functions during the menstrual cycle of healthy young women
Authors: MOLDOFSKY HARVEY , LUE FRANKLIN A. , SHAHAL BARUCH , JIANG CHENG‐GAN , GORCZYNSKI REGINALD M.
Published: January 2009

SUMMARY  Animal and human studies have related the sleeping/waking brain to the immune system. Because women are more susceptible to certain immunological illnesses, and sex steroids regulate immune functions, it was investigated whether the diurnal sleep/wake pattern of aspects of cellular immune functions and interleukin‐1 (IL‐1) and IL‐2‐like activities differed during low and high progesterone phases of the menstrual cycle.

Eleven healthy women, mean age 24y, were assessed over 24h with serial venous blood samples. Peripheral blood monocytes were assayed for mitogen responses, i.e. phytohemagglutin (PHA) and pokeweed (PWM) and natural killer (NK) cell activities. Plasma was assayed for IL‐1 and IL‐2‐like activities, cortisol and progesterone. Data were standardized by Z transformation and analysed by repeated‐measures analysis of variance by comparing high (N= 5) vs. low (N= 6) progesterone phases.

During the high progesterone phase, delayed slow‐wave sleep (SWS) onset time and reduced amount of SWS was accompanied by a delay in the decline of NK cell activity, but rise in PHA activity following sleep onset. With the low progesterone phase, the pattern was similar to men with an early sleep decline in NK cell and late sleep rise in PHA activities. PWM rose during the night and plasma IL‐1‐like activity peaked during midday and during nocturnal sleep irrespective of the amount of progesterone.

Slow‐wave sleep and sleep‐related NK cell and PHA activities differed over the menstrual cycle, but not PWM response. Increases in plasma IL‐1 functions during midday and night are consistent with predisposition to sleepiness during these times.
Age trends in the sleep EEG of healthy older men and women
Authors: LARSEN LAWRENCE H. , MOE KAREN E. , VITIELLO MICHAEL V. , PRINZ PATRICIA N.
Published: January 2009

SUMMARY  The all‐night sleep EEGs of 314 (191 women, 123 men) healthy older subjects between the ages of 45 and 90 were studied for age trends in the power spectra of the all‐night NREM sleep EEG. Power spectra of the unnormalized EEG of the women show a power loss in the delta band and a power increase in the beta band with increasing age. For the men no significant trends in the power spectra of the unnormalized EEG were in evidence. A normalization of the power spectra was performed by referencing each logarithmically expressed spectra to its area between 2 Hz and 30 Hz. For both genders the normalized spectra show significant decreases in power at many frequencies below 16 Hz and significant increases in power at frequencies above 18 Hz with increasing age. The age trends observed in the spectra of this population (45‐90y age group) are about a third of the magnitude of those reported in the literature for subjects between the ages of 20y and 40y.
Is the SF 36 sensitive to sleep disruption? A study in subjects with sleep apnoea
Authors: SMITH IAN E. , SHNEERSON JOHN M.
Published: January 2009

SUMMARY  The objectives of this study were to test the sensitivity of the short form 36 health survey questionnaire (SF 36) to sleep disruption in patients with obstructive sleep apnoea (OSA) and assess its use as an outcome measure for treatment with nasal continuous positive airway pressure (CPAP). Two hundred and twenty‐three subjects under investigation for snoring and/or daytime somnolence completed the questionnaire at presentation and again after a six month period. Subjects with OSA requiring treatment scored lower on all dimensions of the SF 36 (P<0.05) than normative scores for the general population. The largest differences were for vitality (24%) and social functioning (27.9%). After six months of treatment with CPAP there was an improvement in all scores and the score for vitality was no longer significantly different from that of the general population. The SF 36 is sensitive to the effects of sleep disruption in subjects with obstructive sleep apnoea, is a useful outcome measure for treatment with CPAP and its value in other sleep disorders should be assessed.
Sleep propensity and sleep architecture after bright light exposure at three different times of day
Authors: CARRIER JULIE , DUMONT MARIE
Published: January 2009

SUMMARY  The aim of this work was to study the effects of bright light‐induced circadian phase shifts on sleep propensity and sleep architecture while the timing of the sleep/wake cycle is kept constant. Twenty‐three normal subjects underwent an 11‐day study including: (i) baseline sleep and vigilance evaluation; (ii) baseline evaluation of the circadian temperature rhythm with a 40‐h constant routine; (iii) five hours of bright light exposure on each of three days; (iv) post‐treatment sleep and vigilance evaluation; (v) post‐treatment circadian rhythm evaluation with a second 40‐h constant routine. Subjects were divided into three groups: eight subjects were exposed to bright light in the morning (‘Morning group’), eight subjects were exposed in the evening (‘Evening group’), and seven subjects were exposed in the afternoon (‘Afternoon group’). After light exposure, the Morning group showed an advance of 1.23 h in the phase of the temperature rhythm, the Evening group showed a delay of 1.62 h, and the Afternoon group showed a non‐significant advance of 0.5 h. In support of expectations, early‐night sleep propensity was decreased by evening bright light, was increased in almost all subjects exposed to morning bright light, and was not changed by afternoon bright light exposure. The phase shift created by bright light exposure did not seem to be large enough to have a systematic effect on sleep consolidation or on REM sleep parameters in any of the three groups, suggesting that these variables are less sensitive to alterations in phase of the circadian oscillator than early‐night sleep propensity.
Modafinil, d‐amphetamine and placebo during 64 hours of sustained mental work. II. Effects on two nights of recovery sleep
Authors: BUGUET A. , MONTMAYEUR A. , PIGEAU R. , NAITOH P.
Published: January 2009

SUMMARY  Polysomnograms were obtained from 37 volunteers, before (baseline) and after (two consecutive recovery nights) a 64‐h sleep deprivation, with (d‐amphetamine or modafinil) or without (placebo) alerting substances. The drugs were administered at 23.00 hours during the first sleep deprivation night (after 17.5 h of wakefulness), to determine whether decrements in cognitive performance would be prevented; at 05.30 hours during the second night of sleep deprivation (after 47.5 h of wakefulness), to see whether performance would be restored; and at 15.30 hours during the third day of continuous work, to study effects on recovery sleep. The second recovery night served to verify whether drug‐induced sleep disturbances on the first recovery night would carry over to a second night of sleep. Recovery sleep for the placebo group was as expected: the debt in slow‐wave sleep (SWS) and REM sleep was paid back during the first recovery night, the rebound in SWS occurring mainly during the first half of the night, and that of REM sleep being distributed evenly across REM sleep episodes. Recovery sleep for the amphetamine group was also consistent with previously published work: increased sleep latency and intrasleep wakefulness, decreased total sleep time and sleep efficiency, alterations in stage shifts, Stage 1, Stage 2 and SWS, and decreased REM sleep with a longer REM sleep latency. For this group, REM sleep rebound was observed only during the second recovery night. Results for the modafinil group exhibited decreased time in bed and sleep period time, suggesting a reduced requirement for recovery sleep than for the other two groups. This group showed fewer disturbances during the first recovery night than the amphetamine group. In particular, there was no REM sleep deficit, with longer REM sleep episodes and a shorter REM latency, and the REM sleep rebound was limited to the first REM sleep episode. The difference with the amphetamine group was also marked by less NREM sleep and Stage 2 and more SWS episodes. No REM sleep rebound occurred during the second recovery night, which barely differed from placebo. Hence, modafinil allowed for sleep to occur, displayed sleep patterns close to that of the placebo group, and decreased the need for a long recovery sleep usually taken to compensate for the lost sleep due to total sleep deprivation.
Acute mood improvement after dextroamphetamine and methylphenldate in narcolepsy
Authors: ZWICKER J. , BRUCK D. , PARKES J. D. , BROUGHTON R. J.
Published: January 2009

SUMMARY  Mood changes following ingestion of dextroamphetamine (D‐AMP) or methylphenidate (MPH) were examined in 40 narcoleptic patients. The Profile of Mood Status (POMS) and eight additional adjectives describing feelings were used to quantify changes in mood before taking stimulant medication and approximately 90 minutes after ingestion of medication. No significant differences were found between the effects of the two stimulants. When the data from D‐AMP and MPH were combined, significantly higher ratings on the POMS factor of Vigour‐Activity and the adjectives of ‘confident’, ‘talkative’ and ‘competitive’ were found. Lower ratings after medication were noted for the POMS factors of Fatigue‐Inertia, Depression‐Dejection and Confusion‐Bewilderment (all P < 0.001). These effects are similar to those previously reported in normal subjects as well as in certain other patient populations. The findings indicate a possible therapeutic role of stimulant medication not only for the treatment of excessive sleepiness but also for improving affect, motor and mental vigour, and aspects of cognition.
Haemodynamics during sleep: old results and new perspectives
Authors: COCCAGNA GIORGIO , LUGARESI ELIO
Published: January 2009

SUMMARY  After the advent of polygraphic recordings in the 1960s a great deal of interest focused on cardiocirculatory and respiratory activity during sleep.

The Bologna sleep laboratory was the first to make direct recordings of systemic arterial pressure, pulmonary arterial pressure and alveolar ventilation in normal subjects, measuring gas‐blood values during different sleep stages. In the 1960s, neurophysiologists rediscovered a syndrome known to pneumologists for a decade as Pickwickian Syndrome. Polygraphic studies performed in sleep laboratoires all over Europe (Germany, France and Italy) led to a major discovery: the syndrome was not caused by respiratory overload due to obesity, but usually by the presence of obstructive apnoeas arising during sleep. By means of continuous sleep recordings, our laboratory documented the severe repercussions of apnoeas on ventilatory and cardiocirculatory functions. Hypnologists pointed to tracheostomy as the logical effective treatment for the syndrome. Surgery was first performed in Germany by Kuhlo and coworkers and then in Bologna.

In the early 1970s, following the Bologna group's research, there emerged the now accepted concept that obstruction of the upper airways is a continuum stretching from snoring to full‐blown sleep apnoea syndrome. The Bologna team was also the first to conduct epidemiological surveys that indicated that snoring is a relevant risk factor for the cardiocirculatory system.

Here the trends of haemodynamic and ventilatory parameters during sleep are investigated in syndromes of obstructive respiratory failure. The conclusion is that sleep, particularly REM‐sleep, exacerbates all these disorders, and the topic provides a basis for a wider look at how cardiocirculatory activity varies during sleep under normal and pathological conditions.
Hypertension and sleep apnoea
Authors: SKATRUD JAMES B. , MORGAN BARBARA
Published: January 2009

SUMMARY  Epidemiological data indicate a link between sleep‐disordered breathing and elevation of arterial pressure. Previous studies suggest increased activity of the sympathetic nervous system in patients with sleep apnoea. The response of muscle sympathetic nerve activity was further investigated in normal, awake subjects following exposure to 20 minutes of asphyxia. Sympathetic nerve traffic increased during exposure and remained elevated even after the return to room air breathing. These findings raise the possibility that this sustained elevation of sympathetic nerve traffic could play a role in the development of daytime hypertension in patients with sleep‐disordered breathing.
Diurnal variation in pulmonary artery pressure
Authors: BRIGDEN G. , RAFTERY E. B.
Published: January 2009

SUMMARY  Previous observations have suggested that pulmonary artery pressure rises during sleep, whereas systemic artery pressure falls. A system has been developed for careful and accurate recording of pulmonary arterial pressure, and applied it to two groups of subjects: patients with heart failure, and patients with chronic stable angina. The results have largely confirmed the nocturnal pressure rise in pulmonary arterial pressure. Detailed analysis strongly suggests that the same physiological mechanisms producing a fall in systemic pressure are responsible for the rise in pulmonary pressure. The precise mechanism remains to be elucidated.
Effects of CPAP on venous return
Authors: FESSLER HENRY E.
Published: January 2009

SUMMARY  Continuous positive airway pressure, like positive end‐expiratory pressure (PEEP), increases lung volume and pleural pressure and usually decreases venous return. The decrease in venous return has been ascribed to a simple increase in right atrial pressure. However, recent studies have demonstrated PEEP also changes the resistive and elastic properties of peripheral veins. PEEP elevates the upstream pressure driving venous return, increases venous resistance, and directly compresses the inferior vena cava. The dogma that PEEP decreases venous return by decreasing the pressure gradient driving blood from the systemic vessels to the heart appears to be untrue.
The effect of decreased intrathoracic pressure on ventricular function
Authors: SCHARF STEVEN M.
Published: January 2009

SUMMARY  Large decreases in inspiratory intrathoracic pressure (ITP) occur during obstructive apnoeas. The cardiac effects of apnoea‐associated decreased ITP come from the interaction of increased preload (venous return) on the right ventricle (RV) and increased afterload on the left ventricle (LV), and are modulated by the autonomic effects of shifts in blood volume and hypoxaemia. During obstructed breathing, venous return increases by as much as three‐fold during inspiration even though mean flow may change little. This leads to a substantial inspiratory increase in RV end‐diastolic and stroke volume. Because of ventricular interdependence, there is a decrease in LV diastolic compliance and corresponding decrease LV preload.

Sustained decreases in ITP (Müller manoeuvre) inhibit LV ejection, and hence increase LV afterload. However, breathing against an obstructed airway (repetitive short Müller manoeuvre) is not necessarily modelled by the sustained manoeuvre. Animal studies indicate that with airway obstruction, for the first beat or two of inspiration the primary effect on the LV is a reduction in stroke volume related to a decrease in preload, and afterload, if anything, decreases. In fact, afterload only increases during early expiration when stroke volume increases. When obstructive and central apnoeas are paired for duration and blood‐gas alterations, there are increases in pulmonary blood volume with central apnoeas and in RV volume with obstructive apnoeas, consistent with the postulation that the primary effect of obstructive apnoeas is on venous return.

In conclusion, the putative role of decreased ITP in increasing LV afterload under conditions appropriate to OSA is not well supported by experimental studies. However, effects with very large swings in ITP as might be seen under the most extreme forms of OSA, and differences in timing of the swings between diastole and systole have yet to be investigated.
Effect of hypertension on upper airway function and sleep apnoea
Authors: SCHWARTZ ALAN R. , ROWLEY JAMES A. , O'DONNELL CHRISTOPHER , KING EARL D. , MAYOR ALEXANDER , SMITH PHILIP L.
Published: January 2009

SUMMARY  Current evidence suggests that elevations in blood pressure during obstructive apnoeic episodes increase pharyngeal collapsibility and the severity of obstructive sleep apnoea.
A dog model to investigate the relationship between obstructive sleep apnoea and blood pressure regulation
Authors: O'DONNELL C. P. , KING E. D. , SCHWARTZ A. R. , SMITH P. L. , ROBOTHAM J. L.
Published: January 2009

SUMMARY  Patients exhibiting obstructive sleep apnoea (OSA) do not display a normal circadian pattern of blood pressure. It is not clear whether this disruption of the circadian blood pressure pattern is a result of the intermittent airway obstruction during sleep or is the result of confounding factors, such as obesity and age, which are common in OSA and may independently affect blood pressure. To determine if a cause and effect relationship exists between repetitive airway obstruction during sleep and blood pressure regulation a chronically instrumented canine model of OSA has been developed. This canine model has been shown to reproduce the characteristic apnoea and hypersomnolence of human OSA. Furthermore, in this model a 12‐h nocturnal period of repetitive airway obstruction during sleep caused an increase in baseline blood pressure of more than 10 mmHg that was sustained for at least two hours following the restoration of normal airway patency. These results imply that there is a cause and effect relationship between intermittent airway obstruction during sleep and elevated blood pressure.
Systemic arterial blood pressure during obstructive sleep apnoea
Authors: CALVERLEY P.M.A. , REES K.
Published: January 2009

SUMMARY  The cardiovascular changes that accompany obstructive apnoeic events are now well recognized, but their relationship to other processes during the apnoea, whether mechanical, chemical or neurophysiological remains unclear. These relationships have been examined by focusing on arterial blood pressure measured non‐invasively using the Finapres device, gas tensions (SaO2, ETCO2), intrathoracic effort (Ppl) and the median EEG frequency (derived from off‐line FFT analysis). Eighteen patients with OSA were studied (mean age 43.7 y, BMI 31.2, A + HI 41.2) during stable NREM sleep. However, not all variables were measured for each patient. Data were analysed for the breath before, at the start, mid and end of the apnoea and immediately afterwards. Mean blood pressure initially fell with the onset of apnoea, remained stable until mid‐apnoea but rose acutely with apnoea termination. The mean systolic and diastolic pressures were greater during inspiration for the initial and mid‐apnoeic efforts, but this difference was reversed at apnoea termination, possibly reflecting the onset of the arousal response. The change in blood pressure over the apnoea was unrelated to apnoea duration and only weakly associated with the intensity of the peak pleural pressure. The rise in blood pressure at end apnoea was related to the fall in SaO2, but not to changes in ETCO2. There was no correlation between the change in EEG frequency and blood pressure over the apnoea as a whole but the increase in blood pressure from the final effort to the first breath correlated with the change in EEG frequency. These data suggest that the change in arterial pressure during an obstructive apnoea are only weakly dependent on the intensity of inspiratory effort made, but are modified by chemical factors and especially changes in sleep state. The close relationship between arousal and change in blood pressure in NREM events confirms the usefulness of cardiovascular markers of arousal responses in OSA.