Maria José Esposito

Postural control after a night without sleep.

The present study analysed the efficiency of postural control after 12 h of nocturnal forced wakefulness using Rombergs test comprising 1 min of recording with eyes-open and 1 min of recording with eyes-closed, with a 1 min break between the two sessions. Our aim was to see if the decreased postural control efficiency after a sleepless night was unspecific (in both eyes-closed and eyes-open conditions) or selective (in only one of the conditions). A total of 55 students spent a whole night awake at our laboratory and were tested at 22:00 and 08:00 h. In general, the results showed that postural sway increased, performing the recording from eyes-open to eyes-closed condition. The statokinesigram length (SL or efficiency of the postural system) increased after the sleepless night, while in eyes-open condition, the length in function of surface (LFS or accuracy of postural control) and Rombergs index (or contribution of vision to maintain posture) significantly decreased. This could indicate that after a night without sleep, there is a slower elaboration of visual inputs in the postural control process. On the basis of these results, the effects of sleep deprivation on cognitive performance were considered from a neuropsychological point of view.

Relationship between preterm birth and circadian typology in adolescence

A possible relationship between preterm birth and circadian typology was investigated in two pilot survey studies involving 13-year-old teen-agers. Two different questionnaires were used: the Junior Morningness-Eveningness Questionnaire (MEQ) (administered to 55 preterm and 210 fullterm subjects) and the Junior Composite Scale (CS) (administered to 40 preterm and 318 fullterm subjects). In both surveys, preterm groups presented significantly higher total scores, indicating a higher propensity to morningness. Indeed in the preterm samples no evening types were found. The results are discussed in relation to recent models of circadian regulation of the sleep-wake cycle.

Time-based prospective remembering: Interference and facilitation in a dual task

The aim of this study was to analyse prospective memory behaviour when people have to fulfil two different intentions whose retention intervals partially overlapped. More specifically, the purpose of the study was to explore the effects of a secondary PM task (either time-based or event-based) on performance of a main time-based PM task. Four embedded conditions were tested: two event-based ones and two time-based ones. The time- and event-based interpolated tasks differed in how closely their target time was to the 20-minute response required by the main time-based task (16th and 19th min., respectively). The results indicated that when a main time-based prospective memory task shares a portion of the retention interval with a second time-based prospective task, this overlapping facilitated performance on the main task. However, the interpolated tasks appeared to be affected by the moment in which they were administered during the execution of the main time-based task. More specifically, a decrease in the interpolated task performance was observed when this was time-based and had to be executed very closely to the target time of the main task. On the contrary, when the two tasks were different (event-based vs. time-based), there was neither interference, nor facilitation.

Circadian motor asymmetries before and after prolonged wakefulness in humans

It was hypothesized that the relative superiority of the non-dominant hand movements during late evening could arise from a more pronounced homeostatic deactivation of the left hemisphere. We tested such hypothesis collecting motor activity before and after prolonged wakefulness. Fifty-one right-handed subjects wore actigraphs on both left and right wrist for three consecutive days (baseline-sleep deprivation-sleep recovery). We replicated higher motor activity in left hand respect to the right hand at 22:00 and 23:00 h, but only in baseline condition. The results provide the evidence that circadian motor asymmetries do not seem to express homeostatic processes.

Bizarreness of size and shape in dream images

Bizarreness in dreams is defined as an unusual combination of features in the phenomenal unified consciousness, that is, an incoherent simulation of the waking world. The present study investigated the specific mechanisms underlying dream image production and the phenomenal unity of consciousness by focusing on size and shape bizarreness. Data were derived from a Dream Data Bank of experimental dream studies. Analyses revealed that feature distortion was quite infrequent. Results are discussed in terms of cognitive processes proposed in a dream production model. Theoretical cognitive constructs, such as Kosslyns imagery model, memory systems functioning, and binding, were used to speculate about these two specific types of bizarreness.

Prospective time estimation over a night without sleep

Abstract The aim of the present study was to investigate the time of night effect on prospective time estimation efficiency. Fifty-four participants took part in six consecutive experimental sessions from 10:00 p.m. to 8:00 a.m. at intervals of 2 h, during which they had to carry out two kinds of tasks (simple reaction time and prospective time estimation), give an evaluation of their subjective alertness, and record body temperature. In agreement with previous data on body temperature, subjective alertness and performance in simple reaction time showed a significant decrease during the night, while performance in prospective time estimation did not change over the night. Taking into account circadian typology we found that morning-types tended to produce significantly shorter time intervals and less time estimation accuracy than evening-types. With reference to recent cognitive timing models and data derived from free-running conditions, it is hypothesised that internal pace-makers pulse at different rates between the extreme chronotypes.

Sleep Deprivation and Time-Based Prospective Memory.

STUDY OBJECTIVES To evaluate the effect of sleep deprivation on time-based prospective memory performance, that is, realizing delayed intentions at an appropriate time in the future (e.g., to take a medicine in 30 minutes). DESIGN Between-subjects experimental design. The experimental group underwent 24 h of total sleep deprivation, and the control group had a regular sleep-wake cycle. Participants were tested at 08:00. SETTINGS Laboratory. PARTICIPANTS Fifty healthy young adults (mean age 22 ± 2.1, 31 female). INTERVENTIONS 24 h of total sleep deprivation. MEASUREMENTS AND RESULTS Participants were monitored by wrist actigraphy for 3 days before the experimental session. The following cognitive tasks were administered: one time-based prospective memory task and 3 reasoning tasks as ongoing activity. Objective and subjective vigilance was assessed by the psychomotor vigilance task and a visual analog scale, respectively. To measure the time-based prospective memory task we assessed compliance and clock checking behavior (time monitoring). Sleep deprivation negatively affected time-based prospective memory compliance (P < 0.001), objective vigilance (mean RT: P < 0.001; slowest 10% RT: P < 0.001; lapses: P < 0.005), and subjective vigilance (P < 0.0001). Performance on reasoning tasks and time monitoring behavior did not differ between groups. CONCLUSIONS The results highlight the potential dangerous effects of total sleep deprivation on human behavior, particularly the ability to perform an intended action after a few minutes. Sleep deprivation strongly compromises time-based prospective memory compliance but does not affect time check frequency. Sleep deprivation may impair the mechanism that allows the integration of information related to time monitoring with the prospective intention.

La tipologia circadiana come fattore di rischio nel consumo di sostanze psicoattive

Da un punto di vista cronopsicologico si distinguono tre categorie di individui che fra loro presentano pattern di attivazione diversi nel corso della giornata: mattutini, intermedi e serotini. Precedenti ricerche hanno mostrato che i tipi serotini sono quelli che tendono ad utilizzare con piu frequenza sostanze psicoattive. Allo scopo di replicare tali evidenze in un campione di individui italiani, e di valutare se l’utilizzo di tali sostanze risulti differenziato nei diversi cronotipi in funzione del proprio livello circadiano di attivazione, ad un campione di 205 studenti universitari e stato somministrato un questionario sugli stili di vita. I risultati confermano che i soggetti serotini tendono ad utilizzare con piu frequenza alcune sostanze psicoattive, in particolare nicotina e alcool. L’ipotesi secondo la quale l’assunzione di sostanze psicoattive avviene in modo differenziato nelle due tipologie in relazione all’effetto, di attivazione o relax, che si vuole ottenere nei diversi momenti della giornata non sembra essere confermata dai dati di questa ricerca. Emerge comunque chiaramente che gli studenti serotini tendono piu dei loro colleghi mattutini a fare un maggiore uso di sostanze psicoattive, esponendosi con piu frequenza a comportamenti a rischio, potenzialmente dannosi per il loro benessere. Questo ultimo risultato viene discusso in relazione a dati recenti della letteratura scientifica, secondo i quali la tipologia serotina sembra essere un fattore di rischio in relazione al consumo di sostanze psicoattive.

Single and Sequential REM sleep episodes in humans: a phylogenetic left-over?

The occurrence of REM sleep in the rat appears to be under the control of either sleep related processes and homeostatic regulation of physiological variables. With respect to this, it has been observed that in this species REM sleep may occur in the form of two types of episodes, Single and Sequential episodes, which are supposed to play a different functional role. Since it is possible to distinguish Single and Sequential REM sleep episodes also in human beings, the aim of this pilot study was to asses whether a sleep deprivation may differently affect these two types of REM episodes. The sleep deprivation was induced in young human subjects by a progressive restriction of sleep within the same night period. Seventy-two PSG tracing belonging to six subjects have been analyzed. The results show that sleep deprivation does not significantly affect the relative occurrence of Single and Sequential REM sleep episodes, suggesting that in human beings these two types of REM episodes might not have a different functional role.