Corrado Cavallero

Heart rate variability during sleep as a function of the sleep cycle

In this work, in order to evaluate whether autonomic differences distinguish REM sleep and NREM sleep through the whole sleeping period, statistical analysis on spectral power associated with low frequency and high frequency bands were performed on the whole polysomnographic recording, considering the sleep cycle as a unit of sleep. Our results from nine subjects show that power associated with low frequency is higher in REM sleep than in NREM sleep, while power associated with high frequency is significantly higher in NREM sleep than in REM sleep. Differences between REM sleep and NREM sleep are not of the same magnitude within the whole sleep episode and, independent of sleep stages, specific trends are observable in the autonomic control of heart rate during the night.

Effects of sleep reduction on spatial attention

To investigate the effects exerted by sleep loss on specific attentive components the performance to a simple reaction time task and to a cued reaction time task were recorded at regular intervals during days following either 8 or 3 h of uninterrupted sleep. Eleven subjects took part in the experiment. The results show that, notwithstanding a general reduction of alertness produced by sleep curtailment (as indicated by the increase of reaction times in the simple reaction time task), in the cued reaction time task only the reaction times to invalidly cued targets significantly increase, while no difference is observed when attention is summoned by a valid cue. This result suggests that the mechanisms underlying orienting of attention are differentially affected by the reduction of alertness level.

Comparing Sleep‐Loss Sleepiness and Sleep Inertia: Lapses Make the Difference

To compare the behavioral effects of sleep‐loss sleepiness (performance impairment due to sleep loss) and sleep inertia (period of impaired performance that follows awakening), mean response latencies and number of lapses from a visual simple reaction‐time task were analyzed. Three experimental conditions were designed to manipulate sleepiness and sleep‐inertia levels: uninterrupted sleep, partial sleep reduction, and total sleep deprivation. Each condition included two consecutive nights (the first always a night of uninterrupted sleep, and the second either a night of uninterrupted sleep, a night when sleep was reduced to 3 h, or a night of total sleep deprivation), as well as two days in which performance was assessed at 10 different time points (08:00, 08:30, 09:00, 09:30, 10:00, 11:00, 14:00, 17:00, 20:00, and 23:00 h). From 08:00 to 09:00 h, reaction times in the partial sleep‐reduction and total sleep‐deprivation conditions were at a similar level and were slower than those observed in the uninterrupted sleep condition. In the same time period, the frequency of lapses in the total sleep‐deprivation condition was higher than in the partial sleep‐reduction condition, while this latter condition never differed from the uninterrupted sleep condition. The results indicate that both sleep inertia and sleep‐loss sleepiness lead to an increase in response latencies, but only extreme sleepiness leads to an increase in lapse frequency. We conclude that while reaction times slow as a result of both sleep inertia and sleep‐loss sleepiness, lapses appear to be a specific feature of sleep‐loss sleepiness.

Twenty-Four Hours of Total Sleep Deprivation Selectively Impairs Attentional Networks

Performance decrements after sleep loss have been extensively studied and are usually attributed to generic attentional deficits. This claim, however, is based on the view of attention as a unitary construct, despite evidence that it should be considered a multidimensional cognitive ability. The aim of the present study was to evaluate the impact of one night of sleep deprivation on the efficiency of three attentional networks, defined by Posner and Raichle (1994) in anatomical and functional terms, as alerting, orienting, and executive control. Thirty participants performed the Attention Network Test at 9:00 a.m. following two different sleep conditions: baseline (a normal night of sleep) and deprivation (24 hrs of wakefulness). Results showed an overall slowing in reaction times and a significant decrease in accuracy after sleep deprivation. Sleep deprivation selectively affected the three attentional networks, given that only executive control efficacy significantly decreased after sleep deprivation. By contrast, phasic alerting and orienting showed no differences in the two sleep conditions. Thus, performance deficits following sleep deprivation do not reflect global attentional deficits.

Significance of Automatically Detected Word Recurrences in Dream Associations

Verbal data files including dream reports and associations with the report items were subjected to automatic analysis aiming at the recognition of word recurrences. The research was based on the following assumptions: the associations can provide information about the dream sources; the recognition of word recurrences in text files can be a useful tool for the study of dreaming; the identification of links between different dream sources can provide an interesting insight into the phenomenon of dreaming. The principal result obtained was that word recurrences often evidence possible significant links between dream sources. A number of the possible links evidenced by the automatic analysis not only escaped the subjects notice, but might also be unexpected for an analyzer not assisted by a computer.

Adolescents’ Appraisal of Homophobic Epithets: The Role of Individual and Situational Factors

ABSTRACT Homophobic epithets have become commonly used insults among adolescents. However, evidence suggests that there are differences in how these homophobic epithets are evaluated based on beliefs held by the observer and the context in which they are used. To examine this, Italian high school students were asked to rate the offensiveness of homophobic epithets, as well as to consider how they or others would react to homophobic epithets across various situations. Homophobic beliefs and beliefs about the social acceptability of homophobic epithets were also examined. It was found that greater perceived social acceptability of homophobic epithets was related to dismissive reactions to their use, whereas homophobic beliefs were predictive of negative emotional reactions but in varying ways depending on the specific context. The results indicate that homophobic epithets may not always be perceived as homophobic by adolescents, and that attempts to alter the social acceptability of these insults may be an effective manner of reducing their use.

REM sIeep = dreaming: The never-ending story

It has been widely demonstrated that dreaming occurs throughout human sleep. However, we once again are facing new variants of the equation “REM sleep = Dreaming.” Nielsen proposes a model that assumes covert REM processes in NREM sleep. I argue against this possibility, because dream research has shown that REM sleep is not a necessary condition for dreaming to occur. [Nielson]