An innovative biofilter technology for reducing environmental spreading of emerging pollutants and odour emissions during municipal sewage treatment.

Wastewater treatment plants (WWTPs) are known sources of contaminants of emerging concern (CECs) spreading into the environment, as well as, of unpleasant odors. CECs represent a potential hazard for human health and the environment being pharmaceutical or biologically active compounds and they are acquiring relevance in European directives. Similarly, the public concern about odour emissions from WWTPs is also increasing due to the decreasing distance between WWTP and residential areas. This study focuses on the effectiveness of the recently developed MULESL technology (MUch LEss SLudge; WO2019097463) in removing CECs and limiting odour emissions from WWTPs. MULESL technology has been developed for its ability to reduce up to 80% the sludge production from WWTPs. However, it is ought to evaluate if the benefits coming from sludge production reduction do not invalidate CECs removal or negatively affect odour emissions. Thus, the performances of a MULESL and a conventional WWTP (flow rate of 375 m3/d and 3600 m3/d, respectively) were compared while treating the same municipal sewage. Whereas both plants succeeded in removing the traditional gross parameters characterizing wastewaters (e.g. chemical oxygen demand, nitrogen), the MULESL was much more effective than the conventional one in terms of CECs removal for about 60% of the identified compounds showing, however, the same or lower effectiveness for about 30% and 10% of them, respectively. This result was attributed to the high sludge retention time and biomass concentration in the MULESL (enabling enrichment of slow growing microorganisms and forcing biomass to use unusual substrates, respectively), and to the biomass feature to grow in the form of biofilm and granules (favoring micropollutants absorption on biomass). Furthermore, odour impact analysis has shown that the MULESL was characterized by a much lower impact, i.e. 45% lower than that of primary and secondary treatments of the conventional WWTP.

Sleep electroencephalography and brain maturation: developmental trajectories and the relation with cognitive functioning.

Sleep has a crucial role in brain functioning and cognition, and several sleep electroencephalography (EEG) hallmarks are associated with intellectual abilities, neural plasticity, and learning processes. Starting from this evidence, a growing interest has been raised regarding the involvement of the sleep EEG in brain maturation and cognitive functioning during typical development (TD). The aim of this review is to provide a general framework about the maturational changes and the functional role of the human sleep EEG during TD from birth to late adolescence (≤22 years). The reviewed findings show large developmental modifications in several sleep EEG hallmarks (slow wave activity, sleep spindles, theta activity, and cyclic alternating pattern) during TD, and many studies support the notion of an active role of sleep slow wave activity in supporting brain maturation. Moreover, we focus on the possible relation between sleep microstructure, intelligence, and several memory domains (declarative, emotional, procedural), showing that sleep EEG oscillations seem involved in intellectual abilities and learning processes during TD, although results are often conflicting and divergent from findings in adults. Starting from the present literature, we propose that larger methodological uniformity, greater attention to the topographical and maturational aspects of the sleep EEG oscillations and their mutual interactions, and a higher number of longitudinal studies will be essential to clarify the role of the sleep EEG in cognitive functioning during TD.

Infodemiological patterns in searching medication errors: relationship with risk management and shift work.

INTRODUCTION: Western world health care systems have been trying to improve their efficiency and effectiveness in order to respond properly to population aging and non-communicable diseases epidemic. Treatment of the elderly population is becoming complex due to the high number of prescribed drugs because of multimorbidity. Errors in drugs administration in different health care related settings are an actual important issue due to different causes. Aim of this observational study is to measure the online interest in seeking medication errors information related to risk management and shift work. MATERIALS AND METHODS: We investigated Google Trends® for popular search relating to medication errors, risk management and shift work. Relative search volumes (RSVs) were evaluated from 2008 to 2018. A comparison between RSV curves related to medication errors, risk management and shift work was carried out. Then, we compared the world to Italian search. RESULTS: RSVs were persistently higher for risk management than for medication errors (mean RSVs 069 vs. 48%) and RSVs were stably higher for medication errors than shift work (mean RSVs 48 vs. 22%). In Italy, RSVs were much lower compared to the rest of the world, and RSVs for medication errors during the study period were negligible. Mean RSVs for risk management and shift work were 3 and 25%, respectively. RSVs related to medication errors and clinical risk management were correlated (r=0.520, p<0.0001). CONCLUSIONS: Google Trends® search query volumes related to medication errors, risk management and shift work are different. RSVs for risk management are higher, and they are correlated with medication errors. Also, shift work search appears to be lower. These results should be interpreted in order to correctly evaluate how to decrease the number of medication errors in different health care related setting.

Electrical stimulation of the frontal cortex enhances slow-frequency EEG activity and sleepiness.

Our aim was to enhance the spontaneous slow-frequency EEG activity during the resting state using oscillating transcranial direct currents (tDCS) with a stimulation frequency that resembles the spontaneous oscillations of sleep onset. Accordingly, in this preliminary study, we assessed EEG after-effects of a frontal oscillatory tDCS with different frequency (0.8 vs. 5 Hz) and polarity (anodal, cathodal, and sham). Two single-blind experiments compared the after effects on the resting EEG of oscillatory tDCS [Exp. 1=0.8 Hz, 10 subjects (26.2 ± 2.5 years); Exp. 2=5 Hz, 10 subjects (27.4 ± 2.4 years)] by manipulating its polarity. EEG signals recorded (28 scalp derivations) before and after stimulation [slow oscillations (0.5-1 Hz), delta (1-4 Hz), theta (5-7 Hz), alpha (8-12 Hz), beta 1 (13-15 Hz) and beta 2 (16-24 Hz)] were compared between conditions as a function of polarity (anodal vs. cathodal vs. sham) and frequency of stimulation (0.8 vs. 5 Hz). We found a significant relative enhancement of the delta activity after the anodal tDCS at 5 Hz compared to that at 0.8 Hz. This increase, even though not reaching the statistical significance compared to sham, is concomitant to a significant increase of subjective sleepiness, as assessed by a visual analog scale. These two phenomena are linearly related with a regional specificity, correlations being restricted to cortical areas perifocal to the stimulation site. We have shown that a frontal oscillating anodal tDCS at 5 Hz results in an effective change of both subjective sleepiness and spontaneous slow-frequency EEG activity. These changes are critically associated to both stimulation polarity (anodal) and frequency (5 Hz). However, evidence of frequency-dependence seems more unequivocal than evidence of polarity-dependence.

Indoor air quality (IAQ) assessment in a multistorey shopping mall by high-spatial-resolution monitoring of volatile organic compounds (VOC).

In order to assess indoor air quality (IAQ), two 1-week monitoring campaigns of volatile organic compounds (VOC) were performed in different areas of a multistorey shopping mall. High-spatial-resolution monitoring was conducted at 32 indoor sites located in two storehouses and in different departments of a supermarket. At the same time, VOC concentrations were monitored in the mall and parking lot area as well as outdoors. VOC were sampled at 48-h periods using diffusive samplers suitable for thermal desorption. The samples were then analyzed with gas chromatography-mass spectrometry (GC-MS). The data analysis and chromatic maps indicated that the two storehouses had the highest VOC concentrations consisting principally of terpenes. These higher TVOC concentrations could be a result of the low efficiency of the air exchange and intake systems, as well as the large quantity of articles stored in these small spaces. Instead, inside the supermarket, the food department was the most critical area for VOC concentrations. To identify potential emission sources in this department, a continuous VOC analyzer was used. The findings indicated that the highest total VOC concentrations were present during cleaning activities and that these activities were carried out frequently in the food department. The study highlights the importance of conducting both high-spatial-resolution monitoring and high-temporal-resolution monitoring. The former was able to identify critical issues in environments with a complex emission scenario while the latter was useful in interpreting the dynamics of each emission source.

Hippocampal sleep spindles preceding neocortical sleep onset in humans.

The coexistence of regionally dissociated brain activity patterns -with some brain areas being active while other already showing sleep signs- may occur throughout all vigilance states including the transition from wakefulness to sleep and may account for both physiological as well as pathological events. These dissociated electrophysiological states are often characterized by multi-domain cognitive and behavioral impairment such as amnesia for events immediately preceding sleep. By performing simultaneous intracerebral electroencephalographic recordings from hippocampal as well as from distributed neocortical sites in neurosurgical patients, we observed that sleep spindles consistently occurred in the hippocampus several minutes before sleep onset. In addition, hippocampal spindle detections consistently preceded neocortical events, with increasing delays along the cortical antero-posterior axis. Our results support the notion that wakefulness and sleep are not mutually exclusive states, but rather part of a continuum resulting from the complex interaction between diffuse neuromodulatory systems and intrinsic properties of the different thalamocortical modules. This interaction may account for the occurrence of dissociated activity across different brain structures characterizing both physiological and pathological conditions.

History of allergy is a predictor of adverse events in unstable angina treated with coronary angioplasty.

BACKGROUND: The aim was to investigate prognostic relevance of history of allergy in subjects with unstable angina treated with coronary angioplasty. METHODS: Fifty-seven consecutive patients with unstable angina who underwent coronary angioplasty were enrolled in the study and were divided into two groups: those with a history of allergy (Group A, N = 15); and controls (Group C, N =42). Major adverse cardiac events were recorded over a six-month follow-up period. Patients with primary or unsuccessful angioplasty and patients treated with drug eluting stent were excluded from the study. RESULTS: Group A patients (history of allergy) showed a 46.67% incidence of major adverse cardiac events at six-month follow-up (vs. 9.52% Group C, p < 0.01): results remained significant even in a multiple Cox regression analysis (hazard ratio 7.17, 95% CI 1.71-29.98, p < 0.01). CONCLUSION: History of allergy is an independent predictor of major adverse cardiac events after coronary angioplasty in a six-month follow-up period in unstable angina.

The impact of one night of sleep deprivation on moral judgments.

Recent studies have shown the existence of a relationship between sleep and moral judgment. In this study, we investigated whether one night of sleep deprivation affects the ability to judge the appropriateness of moral dilemmas. Forty-eight students had to judge 30 moral dilemmas at test, after a night of home sleep, and another 30 dilemmas at retest, following one night of continuous wakefulness. The 60 dilemmas (20 moral impersonal, 20 moral personal, and 20 non-moral) were selected from Greene's dilemmas. Both groups judged the appropriateness of personal and impersonal dilemmas in the same way. A close to significant effect of sleep deprivation was observed on the reaction times for impersonal moral dilemmas, to which the deprived subjects responded faster (p = .05) than the control subjects. However, this was not the case for personal ones, for which no difference was significant. This result shows a greater ease/speed in responding to the (impersonal) dilemmas, which induce low emotional engagement after sleep deprivation, although the willingness to accept moral violations is not affected. This suggests that one night of sleep loss selectively influences the response speed only for moral impersonal dilemmas, probably due to disinhibition processes. The quality of moral judgment dilemmas does not seem to be easily influenced by a single night of sleep deprivation, but only by a longer lack of sleep.

A specific deficit in spatial memory acquisition in post-traumatic stress disorder and the role of sleep in its consolidation.

Posttraumatic stress disorder (PTSD) is characterized by the presence of anatomo-functional hippocampal alterations. To date, the ability to orient within the environment, which relies on hippocampal integrity, has never been investigated in PTSD. We hypothesized that the ability to form a cognitive map of the environment would be impaired in PTSD. Moreover, spatial memory consolidation benefits from postlearning sleep. Because PTSD individuals often complain about sleep disturbances, we hypothesized that any sleep effect on memory performance would be hampered in these subjects. Twenty-two subjects, all survivors of the L'Aquila 2009 earthquake, were divided into a PTSD and a control group, based on clinical evaluation. After an acquisition phase, they were tested twice ("test" and "retest") on a virtual navigation task. In addition, participants were administered the Digit Span and Task Switching. Subjective sleep quality and sleep disturbances were also assessed. The two testing sessions were on consecutive mornings, interspersed with a night of sleep. During the acquisition phase, the PTSD group took more than twice as long to form a cognitive map of the environment compared to the control group. However, once this phase was successfully completed, the two groups did not differ at test, but they tendentially differed at postsleep retest. Additional analyses comparing performances between groups on test-retest difference scores confirm that sleep-dependent consolidation may be differentially affected in the two groups. Our findings are strictly confined to the navigation performance, excluding a generalized cognitive deficit. PTSD also reported more subjective sleep disturbances and shorter sleep time than controls, which were correlated to worse performance at retest. The specific deficit in the formation of a cognitive map reported in PTSD may be related to hippocampal dysfunctions as well as to the sleep disturbances experienced by these patients. The possible deficiency of sleep-dependent spatial performance improvement should however be confirmed by further studies comprising a wake control group.

Electroencephalographic sleep inertia of the awakening brain.

Sleep inertia (SI) denotes a period of hypovigilance, confusion and impaired cognitive and behavioral performance that immediately follows awakening. Based on the observation that the reactivation of some cortical areas is faster than other upon awakening, here we examined regional differences between presleep and postsleep waking period. Moreover, we also compared rapid eye movements (REM) and stage 2 non-rapid eye movements (NREM) awakenings in a within-subject design. Presleep and postsleep waking electroencephalogram (EEG; 5 min with eyes-closed and 5 min with eyes-open) of 18 healthy subjects (12 males, mean age=23.8±2.3 years) were recorded from 19 derivations. Participants slept for two consecutive nights in the laboratory. In one night they were awakened from stage 2 NREM, while in the other from REM sleep. EEG power spectra were calculated across the following bands: delta (1-4 Hz), theta (5-7 Hz), alpha (8-12 Hz), beta-1 (13-16 Hz) and beta-2 (17-24 Hz). Moreover, a detailed hertz-by-hertz analysis has been repeated in the 2-4 Hz frequency range. Postsleep wakefulness, compared to presleep, is characterized by a generalized decrease of higher beta-1 and beta-2 EEG power over almost all scalp locations. A detailed analysis of topographical modifications in the low-frequency range showed that postsleep wakefulness is characterized by an increased delta activity in the posterior scalp locations, and by a concomitant frontal decrease compared to presleep. Moreover, it was found a prevalence of EEG power in the high frequency ranges (beta-1 and beta-2) upon awakening from stage 2 compared to REM awakenings over the left anterior derivations. Altogether these findings support the hypothesis that a generalized reduction in beta activity and increased delta activity in more posterior areas upon awakening may represent the EEG substratum of the sleep inertia phenomenon.

Immune response to cytolethal distending toxin of Aggregatibacter actinomycetemcomitans in periodontitis patients.

BACKGROUND AND OBJECTIVE: Cytolethal distending toxin (CDT) is a genotoxin produced by Aggregatibacter actinomycetemcomitans. In spite of its association with pathogenesis, little is known about the humoral immune response against the CDT. This study aimed to test whether subgingival colonization and humoral response to A. actinomycetemcomitans would lead to a response against CDT. MATERIAL AND METHODS: Sera from periodontally healthy, localized and generalized aggressive periodontitis and chronic periodontitis subjects (n = 80) were assessed for immunoglobulin G titers to A. actinomycetemcomitans serotypes a/b/c and to each CDT subunit (CdtA, CdtB and CdtC) by ELISA. A. actinomycetemcomitans subgingival levels and neutralization of CDT activity were also analyzed. RESULTS: Sera from 75.0% localized and 81.8% generalized aggressive periodontitis patients reacted to A. actinomycetemcomitans. A response to serotype b was detected in localized (66.7%) and generalized aggressive periodontitis (54.5%). Reactivity to A. actinomycetemcomitans correlated with subgingival colonization (R = 0.75, p < 0.05). There was no correlation between A. actinomycetemcomitans colonization or response to serotypes and the immunoglobulin G response to CDT subunits. Titers of immunoglobulin G to CdtA and CdtB did not differ among groups; however, sera of all generalized aggressive periodontitis patients reacted to CdtC. Neutralization of CDT was not correlated with levels of antibodies to CDT subunits. CONCLUSION: Response to CdtA and CdtB did not correlate with the periodontal status of the subject in the context of an A. actinomycetemcomitans infection. However, a response to CdtC was found in sera of generalized but not of localized aggressive periodontitis subjects. Differences in response to CdtC between generalized and localized aggressive periodontitis subjects indicate that CDT could be expressed differently by the infecting strains. Alternatively, the antibody response to CdtC could require the colonization of multiple sites.

Increased cortical plasticity in the elderly: changes in the somatosensory cortex after paired associative stimulation.

A fundamental feature of the human cortex is the capability to express plastic changes that seem to be present even during physiological aging. The paired associative stimulation (PAS) protocol is a paradigm capable of inducing neuroplastic changes, possibly by mechanisms related to spike timing-dependent associative neuronal activity, and represents a suitable tool for investigating age-dependent neuroplastic modulations of the primary somatosensory cortex (S1). To examine age dependency of S1 plasticity, the amplitude changes of median nerve somatosensory evoked potential (SEP) before and after PAS intervention were investigated in young and elderly subjects. The main finding of our study is that low-frequency medial nerve stimulation paired with transcranial magnetic stimulation over the contralateral cortex enhances S1 excitability. Moreover, the S1 long term potentiation-like plasticity changes as a function of aging, with a significant increase of N20-P25 complex in the elderly compared to young subjects. These results are congruent with the hypothesis that some elderly subjects retain a high level of plasticity in specific neuronal circuits. Such plasticity could represent a compensatory mechanism, in terms of functional reserve of somatosensory cortex, used by the aging brain to counterbalance the cortical degeneration associated with aging.

Psychomotor performance is not influenced by brief repeated exposures to mobile phones.

The present study investigated the presence of a cumulative effect of brief and repeated exposures to a GSM mobile phone (902.40 MHz, 217 Hz modulated; peak power of 2 W; average power of 0.25 W; SAR = 0.5 W/kg) on psychomotor functions. To this end, after each of 3 15-min exposures, both an acoustic simple reaction time task (SRTT) and a sequential finger tapping task (SFTT) were administered to 24 subjects. The present study was unable to detect the cumulative effects of brief and repeated EMF exposure on human psychomotor performance, although there was a non-statistical trend to shorter reaction times. In summary, these data show an absence of effects with these particular exposure conditions; however, possible cognitive effects induced by different signal characteristics cannot be excluded.

Neurophysiological effects of mobile phone electromagnetic fields on humans: a comprehensive review.

In recent years a growing number of people have begun to use mobile phone technology. This phenomenon has raised questions and doubts about possible effects on users' brains. This literature review focuses on the human electrophysiological and neuro-metabolic effects of mobile phone (MP)-related electromagnetic fields (EMFs) published in the last 10 years. To this end, all relevant papers have been reported and, subsequently, a literature selection has been carried out by taking several criteria into account, such as: blind techniques, randomization or counter-balancing of conditions and subjects, detail of exposure characteristics and the statistical analyses used. As a result, only the studies meeting the selection criteria have been described, evaluated and discussed further. The main goal of this review is to provide a clear scenario of the most reliable experiments carried out over the last decade and to offer a critical point of view in their evaluation. It is concluded that MP-EMFs may influence normal physiology through changes in cortical excitability and that in future research particular care should be dedicated to both methodological and statistical control, the most relevant criteria in this research field.

Is the brain influenced by a phone call? An EEG study of resting wakefulness.

We recorded the resting electroencephalogram of 20 healthy subjects in order to investigate the effect of electromagnetic field (EMF) exposure on EEG waking activity and its temporal development. The subjects were randomly assigned to two groups and exposed, in double-blind conditions, to a typical mobile phone signal (902.40 MHz, modulated at 217 Hz, with an average power of 0.25 W) before or during the EEG recording session. The results show that, under real exposure as compared to baseline and sham conditions, EEG spectral power was influenced in some bins of the alpha band. This effect was greater when the EMF was on during the EEG recording session than before it. The present data lend further support to the idea that pulsed high-frequency electromagnetic fields can affect normal brain functioning, also if no conclusions can be drawn about the possible health effects.

Time-course of electromagnetic field effects on human performance and tympanic temperature.

The study aimed to investigate the time-course of electromagnetic field (EMF)-induced effects on human cognitive and behavioral performance and on tympanic temperature. Subjects were randomly assigned to two groups, exposed to a 902.40 MHz EMF before the testing session, or to the same signal during the data collecting session. Following a double-blind paradigm, subjects were tested on four performance tasks: an acoustic simple-reaction time task, a visual search task, an arithmetic descending subtraction task and an acoustic choice-reaction time task. Moreover, tympanic temperature was collected five times during each session. Results indicated an improvement of both simple- and choice-reaction times and an increase of local temperature on the exposed region under the active exposure. There was a clear time-course of the reaction time and temperature data, indicating that performance and physiological measures need a minimum of 25 min of EMF exposure to show appreciable changes.

Reduced sympathetic outflow and adrenal secretory activity during a 40-day stay in the Antarctic.

Human adaptation to unknown and extreme environments requires changes in the psychological and physical homeostasis. We previously reported a significant decrease of anterior pituitary and adrenal hormonal levels and a significant modification of psychophysiological correlates of stress, such as galvanic skin response, after exposure to Antarctica, suggesting a possible decrease of individual arousal. The latter was hypothesized to be correlated with a modification of autonomic balance, mainly represented by a possible reduction of adrenergic output. The aim of the present study was to assess the patterns of hormonal circadian rhythms and the autonomic nervous system balance by means of spectral analysis of heart rate variability (HRV). These parameters were evaluated during 3 sessions (baseline, session 1 and session 2), before, at the beginning and after a 40-day stay in Antarctica (Station of Terra Nova Bay; average temperature in the study period: -11 degrees C, 24 h of light, sea level). In each of the sessions, 6 healthy male subjects underwent a 24-h electrocardiogram and blood sampling (08.00, 12.00, 16.00, 20.00, 24.00 and 08.00 h) for hormonal determinations. The data showed a remarkable decrease of hormonal levels without significant changes in circadian rhythms. Spectral analysis of HRV showed an imbalance of the autonomic nervous system with a relative significant decrease of the low frequency band (0.1 Hz) in session 1 and 2 compared to baseline, which can be functionally interpreted as a relative decrement of the sympathetic component. In conclusion, the exposure to a cold and extreme environment seems to affect autonomic balance over a 40-day period. This is followed by a significant reduction of the anterior pituitary and adrenal hormonal secretory patterns with preserved hormonal circadian rhythms (within the same time period of 40 days). This pattern is suggestive of a trophotropic neurovegetative adaptive process.

The boundary between wakefulness and sleep: quantitative electroencephalographic changes during the sleep onset period.

Microstructural electroencephalographic changes during the wakefulness-sleep transition have been investigated by comparing two definitions of sleep onset: the first occurrence of stage 1 and of stage 2. Power values were calculated across a 1-28-Hz frequency range in a 1-Hz bin resolution in the sleep recordings of 26 normal subjects. Quantitative changes were assessed after averaging individual time series, aligned with respect to the first occurrence of stage 1 or of stage 2. The time course of the single-Hz activity revealed a linear increase of power in the 1-6-Hz range and a linear decrease in the 9-12- and 16-28-Hz ranges during the stage 1 transition. During the stage 2 transition, electroencephalogram power linearly increased in the 1-7- and 14-15-Hz ranges and decreased in the 18-28-Hz range, while the 8-12-Hz range fitted a second-order polynomial curve. The two 'switch' points were also compared in their ability to differentiate Hz by Hz wakefulness from sleep: a lower mean power was found after stage 1 onset in the 9-11-Hz and 20-28-Hz bins and a higher one in the 1-5-Hz bins, while a higher power was found in the 1-8-Hz and 12-16-Hz bins and a lower one in 18-28-Hz bins after stage 2 onset. The time course of three electroencephalographic frequency ranges [delta/theta/sigma (1-7 and 12-16 Hz); beta (17-28 Hz); alpha (8-11 Hz)], grouped on the basis of a principal component analysis, fitted a first-order polynomial curve for the first two ranges, and a second-order polynomial curve for the last, with a progressive decrease during wakefulness, a minimum point during stage 1, and a subsequent increase during stage 2. The uniformly increasing electroencephalographic power across the 1-16-Hz frequency range during stage 2 and the shift of functional meaning for the alpha power during stage 1 point to the start of stage 2 as a more reliable boundary between wakefulness and sleep.

Antero-posterior EEG changes during the wakefulness-sleep transition.

OBJECTIVES: To investigate the brain topography of the human sleep EEG along the antero-posterior axis during the wakefulness-sleep transition, by means of both a single Hz analysis and a grouped-frequency analysis of EEG changes. METHODS: EEG power values were calculated across a 1-28 Hz frequency range in a 1 Hz resolution during the wakefulness-sleep transition of 7 normal subjects. Topographical changes were assessed from C3-A2, C4-A1, Fpz-A1, Fz-A1, Cz-A1, Pz-A1, Oz-A1 recordings, after averaging individual time series, aligned with respect to the onset of stage 2. RESULTS: The single Hz analysis showed that before sleep onset (SO), the <7 Hz slow frequencies were more prominent at the more anterior scalp locations; this anterior prominence was counterbalanced by a reciprocal prevalence across the >8 Hz frequencies of EEG activity from the occipital areas; while the >13 Hz fast frequencies were not characterized by significant antero-posterior differences. After SO, more EEG power was found in the range of slow frequencies at the centro-frontal scalp locations and a second peak of EEG activity was also revealed within the range of the sigma frequency, higher at the centro-parietal scalp locations. No consistent topographical changes were observed within the range of faster EEG frequencies. Grouped-frequency analysis confirmed these results, also pointing to different changes in the alpha frequency as a function of the SO point. CONCLUSIONS: The results suggest that: (a) the alpha rhythm spreads anteriorly as the transition progresses; (b) several anterior areas first synchronize EEG activity; (c) the functional meaning of the EEG bands during the SO period should be partially revised with regard at least to alpha rhythm; (d) SO coincides with the start of stage 2.

Auditory evoked responses upon awakening from sleep in human subjects.

The hypothesis that a state of hypoarousal upon awakening should lead to a decrease in amplitude and an increase in latency of the N1-P2 components of the Auditory Evoked Potentials (AEPs) as compared to presleep wakefulness levels, was evaluated after two nocturnal awakenings and after the final morning awakening from a 7.5-h night of sleep. The amplitude of the N1-P2 complex was reduced upon awakening as compared to presleep wakefulness levels, but only following the first nocturnal awakening, scheduled after the first 2 h of sleep. This result is interpreted as indicating a link between slow wave sleep amount, mainly present during the first part of the night, and lowered levels of brain activation upon awakening. The reaction times, recorded concomitantly to AEPs, were more sensitive to the negative effects of sleep inertia.