Gianluca Ficca

Morning recall of verbal material depends on prior sleep organization

Despite the evidence that sleep may facilitate memory, controversial findings concern the role of sleep states (NREM, REM). We put forward the hypothesis that sleep organization, i.e. the regular occurrence of NREM-REM cycles, more than sleep states per se, may be crucial for the retention of verbal material presented before sleep. An experiment was performed in which recall of verbal material was requested of young subjects after three different kinds of night sleep: undisturbed sleep, fragmented sleep without sleep cycles disorganization, and fragmented sleep interrupted with sleep disorganization. Morning recall of verbal material was impaired after the night with disturbed sleep cycles, whereas it was not after the night with preserved sleep cycles; the amount of REM was similar in both cases. We conclude that the recall of verbal material is greatly affected by sleep cycle disorganization.

A 50-Hz electromagnetic field impairs sleep.

In view of reports of health problems induced by low frequency (50–60Hz) electromagnetic fields (EMF), we carried out a study in 18 healthy subjects, comparing sleep with and without exposure to a 50Hz/1μTesla electrical field. We found that the EMF condition was associated with reduced: total sleep time (TST), sleep efficiency, stages 3+4 slow wave sleep (SWS), and slow wave activity (SWA). Circulating melatonin, growth hormone, prolactin, testosterone or cortisol were not affected. The results suggest that commonly occurring low frequency electromagnetic fields may interfere with sleep.

Sleep organization in the first year of life: Developmental trends in the quiet sleep–paradoxical sleep cycle

The night sleep of 48 healthy drug‐free infants, aged 1–54 weeks, was recorded and analysed in order to show how cycles contribute to sleep episode organization and how the balance among different sleep states (i.e. quiet sleep, paradoxical sleep and ambiguous sleep) within cycles changes as a function of age.

Body movements during night sleep and their relationship with sleep stages are further modified in very old subjects

The night sleep of 12 healthy subjects aged 76-98 was polygraphically investigated in order to analyse body movements and their association with sleep stages at very old age; this group was compared with 11 healthy old subjects aged 61-75 years. In very old subjects sleep is less punctuated by body movements and the association of body movements with each sleep stage is further modified compared to less old subjects. Short-lasting movements emerge indifferently from stage 1, stage 2 and REM sleep, but are significantly less frequent in SWS. Furthermore, in very old subjects the probability of awakening after body movements is higher than in old subjects, suggesting that sleep is more vulnerable to the occurrence of body movements than at previous ages. The difficulty in the elderly to maintain a stable state expresses the inability to sustain and coordinate stable physiological activities characteristic of the old age. In addition, the presence of numerous awakenings, not preceded by movements, supports the hypothesis that the awakening in the very old people may be a sudden event, as should be confirmed by the study of other behavioural and physiological activities preceding awakening.

Increased spontaneous eye blink rate following prolonged wakefulness.

Sleep deprivation (SD) is a technique of sleep-wake manipulation which has been used to treat depression. Changes in neurotransmitter systems, that are also involved in the effects of the antidepressant drugs, have been suggested as the possible mechanisms of action of SD. However, the therapeutic effect of SD is acute and transient, while antidepressant effects of drug treatments are gradual and stable. SD might work throughout mechanisms that are different from those mediating drugs effects. In the present study we analyzed the role of dopamine activity in SD. Spontaneous eye blink rate provides a non invasive measure of central dopamine activity. We assessed eye blink rate across prolonged wakefulness (from 10:00 a.m. to 07:00 a.m.) in 25 young normal subjects. Eye blink rate increased at the end of the wakefulness period. Blink rates and sleepiness as assessed by Karolinska Sleepiness Scale correlated positively with time spent awake. We propose that increased blink rate might reflect a dopamine activation that counteracts sleep drive. Antidepressant effects of sleep deprivation might be related to activation of the physiological mechanisms which regulate wake maintenance.

Effects of different types of hand gestures in persuasive speech on receivers’ evaluations

Hand gestures have a close link with speech and with social perception and persuasion processes, however to date no one has experimentally investigated the role of hand gestures alone in persuasive speech. An experiment with undergraduates was conducted using 5 video-messages in which only hand gestures of the speaker were manipulated along five types. ANOVAs reveal effect of gesture type on receivers’ evaluation of message persuasiveness, speaker communication style effectiveness, and speakers composure and competence. A control study (Experiment 2) confirms that these effects are due to visible gestures. Speech accompanying gestures appear to play a causal role in social perception.

Spontaneous awakenings from sleep in the first year of life.

Spontaneous awakenings from nocturnal sleep were studied in a sample of 48 healthy infants (M = 26, F = 22), in four age groups (1 to 7 weeks, 8 to 15 weeks, 17 to 22 weeks, 25 to 54 weeks). Consistent with previous data, the number of awakenings is reported less frequently at later ages, owing to a lower frequency of awakenings out of REM sleep. Like young adults, infants in all age groups awake more often from REM than from quiet sleep (QS); this is particularly evident in the first 6 months of life, less so in the second. The duration of the bouts of wakefulness following awakenings remains stable with age. Awakenings out of QS are followed by longer periods of wakefulness than those out of REM sleep, although in older infants the duration is considerably reduced. Night sleep first shows a decrease in the number of awakenings out of REM sleep and then continues after the sixth month of life with the shortening of the wakefulness after awakenings out of QS. In the two younger groups, the distribution of the awakenings shows two main peaks and one main peak differently located during the night; a polymodal pattern appears in group 3, and is even more evident in group 4. It should be stressed that several changes as a function of age occur in the second 6 months of life, indicating this as a period of intense developmental change in sleep-wake rhythms.

Body movements during night sleep in healthy elderly subjects and their relationships with sleep stages.

In order to enlighten the profile of body movements during sleep at old age, the night sleep of twelve elderly subjects was polygraphically investigated; seven young healthy subjects were the control group. Significantly less body movements during sleep were found in the elderly compared to young subjects, meaning that the decrease in the number of body movements observed from infancy to childhood up to adulthood also continues at later ages. Differently from young adult, whose sleep body movements mainly occur in stage REM, no specific sleep state and/or stage was preferentially associated with the occurrence of body movements in the elderly. These data may point to an age-related modification in the interaction between motor cortex control and subcortical circuits. Furthermore, when body movements occur in elderly individuals, they are significantly more often followed in the next 60 s by a sleep stage change or by a spontaneous behavioural awakening. This might reflect a peculiar inability of elderly subjects to sustain stable states, and could also suggest that body movements may act as a co-factor in a process, comprising other physiological changes, leading to state shifts.

Rapid eye movement activity before spontaneous awakening in elderly subjects.

Previous research in young subjects found that rapid eye movement (REM) density is higher in those REM phases which are followed by an awakening (REM‐W) than in those preceding NREM (REM‐N), suggesting a ‘gating role’ of REM sleep toward the awakening. It is not yet known whether this evidence is maintained in elderly subjects, who display, relative to young subjects, more awakenings, different sleep states from which the awakenings come (NREM in a high proportion of cases) and a general impairment of rapid eye movement activity (REMA). To investigate this issue, we have compared in three different age groups (young, old and ‘old old’ subjects) the features of REMA, including REM density and the amount and duration of REM bursts, between REM‐W and REM‐N. Whereas in the young REM density is higher in REM‐W than in REM‐N, this difference is already reduced in the old group and fully cancelled in the old old subjects. The evidence that old individuals spontaneously wake up despite the absence of an increase of REMA could imply that in the aged awakening is not preceded by an increase of the arousal level (expressed in REM sleep by the REMA). The similar duration of REM bursts for REM‐W and REM‐N in both groups of old subjects suggests that with age a marked impairment occurs in the organizational aspects of REMs, independently from the following state.

The Effects of Pre-Sleep Learning on Sleep Continuity, Stability, and Organization in Elderly Individuals

Several studies have consistently shown that pre-sleep learning is associated to changes of sleep structure. Whereas previous research has mainly focused on sleep states, namely REM and NREM amount, very little attention has been paid to the hypothesis that pre-sleep learning might improve sleep continuity, stability, and cyclic organization, which are often impaired in aging. Thus, aim of this research was to assess, in a sample of 18 healthy elderly subjects, whether a memory task administered at bedtime would determine changes in any sleep parameter, with special regard to sleep continuity, stability, and organization. To this purpose, a baseline sleep (BL), i.e., a normal sleep with 9-h time in bed (TIB), was compared to a post-training sleep (TR), with the same TIB but preceded by an intensive training session. For the latter, a verbal declarative task was used, consisting in learning paired-word lists, rehearsed, and recalled for three times in a row. To control for individual learning abilities, subjects were administered several sets of lists with increasing difficulty, until they reached an error rate ≥20% at third recall. Relative to BL, TR shows a significant reduction in the frequency of brief awakenings, arousals, state transitions, “functional uncertainty” (FU) periods, and in the percentage of time in FU over total sleep time (TST). A significant increase in the number of complete cycles, total cycle time (TCT), and TCT/TST proportion was also found. All these changes are evenly distributed over the sleep episode. No sleep stage measure display significant changes, apart from a slight reduction in the percentage of Stage 1. Scores at retest are negatively correlated with both the frequency of arousals and of state transitions. Our data suggest that pre-sleep learning can yield a beneficial re-organizing effect on elderlies’ sleep quality. The inverse correlation between recall scores and the measures of sleep continuity and stability provides further support to the role of these features in memory processes.