Intrasleep Wakefulness Research Articles

Dream Activity in Narcoleptic Patients During the COVID-19 Lockdown in Italy.

Some studies highlighted that patients with narcolepsy type-1 (NT1) experience high lucid dream frequency, and this phenomenon has been associated with a creative personality. Starting from the well-known “pandemic effect” on sleep and dreaming, we presented a picture of dream activity in pharmacologically treated NT1 patients during the Italian lockdown. Forty-three NT1 patients completed a web-survey during Spring 2021 and were compared with 86 matched-controls. Statistical comparisons revealed that: (a) NT1 patients showed greater sleepiness than controls; (b) controls showed higher sleep disturbances than NT1 patients, and this result disappeared when the medication effect in NT1 was controlled; (c) NT1 patients reported higher lucid dream frequency than controls. Focusing on dreaming in NT1 patients, we found that (a) nightmare frequency was correlated with female gender, longer sleep duration, higher intrasleep wakefulness; (b) dream recall, nightmare and lucid dream frequency were positively correlated with sleepiness. Comparisons between low and high NT1 lucid dreamers showed that patients more frequently experiencing lucid dreams reported a greater influence of dreaming during wakefulness, especially concerning problem-solving and creativity. Overall, our results are consistent with previous studies on pandemic dreaming carried out on healthy subjects. Moreover, we confirmed a link between lucidity and creativity in NT1 patients. Considering the small sample size and the cross-sectional design, our findings cannot provide a causal relationship between lucid dreams and the COVID-19 lockdown. Nevertheless, they represent a first contribution to address future studies on this issue, suggesting that some stable characteristics could interact with changes provoked by the pandemic.

Pandemic nightmares: Effects on dream activity of the COVID-19 lockdown in Italy.

SummaryCOVID‐19 has critically impacted the world. Recent works have found substantial changes in sleep and mental health during the COVID‐19 pandemic. Dreams could give us crucial information about people's well‐being, so here we have directly investigated the consequences of lockdown on the oneiric activity in a large Italian sample: 5,988 adults completed a web‐survey during lockdown. We investigated sociodemographic and COVID‐19‐related information, sleep quality (by the Medical Outcomes Study‐Sleep Scale), mental health (by the Depression, Anxiety, and Stress Scales), dream and nightmare frequency, and related emotional aspects (by the Mannheim Dream Questionnaire). Comparisons between our sample and a population‐based sample revealed that Italians are having more frequent nightmares and dreams during the pandemic. A multiple logistic regression model showed the predictors of high dream recall (young age, female gender, not having children, sleep duration) and high nightmare frequency (young age, female gender, modification of napping, sleep duration, intrasleep wakefulness, sleep problem index, anxiety, depression). Moreover, we found higher emotional features of dream activity in workers who have stopped working, in people who have relatives/friends infected by or who have died from COVID‐19 and in subjects who have changed their sleep habits. Our findings point to the fact that the predictors of high dream recall and nightmares are consistent with the continuity between sleep mentation and daily experiences. According to the arousal‐retrieval model, we found that poor sleep predicts a high nightmare frequency. We suggest monitoring dream changes during the epidemic, and also considering the implications for clinical treatment and prevention of mental and sleep disorders.

Increased Awakenings From Non-rapid Eye Movement Sleep Explain Differences in Dream Recall Frequency in Healthy Individuals.

BackgroundDreaming is a universal experience, yet there is considerable inter-individual variability in dream recall frequency (DRF). One dominant model, the “arousal-retrieval” model, posits that intra-sleep wakefulness is required for dream traces to be encoded into long-term storage, essentially proposing that a better memory for dreams underlie increased DRF. A recent study utilizing polysomnography combined with an event-related potentials paradigm, provides direct support for this model by demonstrating increased intra-sleep wakefulness in a healthy population by comparing high frequency recallers (HFRs) and low frequency recallers (LFRs). Another study by the same group demonstrated increased regional cerebral blood flow in regions associated with dream production, supporting the premise that HFRs also may produce more dreams.HypothesesThis study investigated the profile of nocturnal awakenings and dream production in healthy HFRs and LFRs. Hypothesis (1a): HFRs will spend significantly more time awake after sleep onset; (1b): HFRs will experience significantly more awakenings across the night, and from rapid eye movement (REM) sleep in particular; (2) HFRs will have significantly higher rates of dream production across the night as measured by REM density.MethodsWe studied two groups of healthy adults: HFRs (n = 19) and LFRs (n = 17) who underwent polysomnographic recordings on two non-consecutive nights.ResultsHypothesis (1a) was confirmed: HFRs spent significantly more time awake after sleep onset. Hypothesis (1b) was partially confirmed: HFRs experienced significantly more awakenings across the night; however, awakenings from REM sleep were comparable. Interestingly, HFRs had significantly more awakenings, as well as a higher number of longer awakenings, from non-rapid eye movement (NREM) stage 2 sleep. Hypothesis (2) was not confirmed: There was no significant difference in rates of REM density between groups.ConclusionThis is the first study to provide evidence that awakenings from NREM 2 sleep might underlie increased DRF in HFRs. This finding coupled with null findings in relation to REM sleep variables, support the premise that inter-individual variability in DRF cannot be ascribed to differences in REM sleep parameters in healthy individuals. Instead, the data indicates that awakenings from NREM sleep is of particular importance in relation to DRF in a healthy population.

Analysis of Sleep Macrostructure in Patients Diagnosed with Parkinson's Disease.

Patients diagnosed with Parkinson’s disease present sleep disorders with a higher frequency than the general population. The sleep architecture in these patients shows variations with respect to the normal population, so in this work it was decided to investigate the characteristics of the macroarchitecture of sleep in patients diagnosed with Parkinson’s disease. A polysomnographic study was carried out on 77 patients diagnosed with Parkinson’s disease. All the studies were processed according to the AASM Manual for the Scoring of Sleep and Associated Events v.2.2, and to the criteria of the International Classification of Sleep Disorders 3rd ed. (2014). Processing was carried out using descriptive statistics, as well as non-parametric analysis for comparison between cases and controls. The group of patients showed significant reductions of the N2, N3, and REM sleep stages when compared with a control group, as well as a significant increase in intra-sleep wakefulness. The number of REM–NoREM sleep cycles and sleep efficiency showed marked reduction compared to the control group. There was a statistically significant difference in the macroarchitecture of sleep between patients diagnosed with Parkinson’s disease and healthy controls.

Objective and Subjective Sleep Efficiency in Adult Patients with Cystic Fibrosis and Impact on Quality of Life.

Poor sleep quality and excessive daytime sleepiness are common in patients with cystic fibrosis (CF), and both are negatively correlated with health-related quality of life (HRQoL). The objective of our study was to evaluate subjective and objective sleep quality in adult CF patients and its effect on HRQoL. This was a descriptive, prospective, cross-sectional study of CF patients > 18years of age. Patients underwent nocturnal polysomnography (PSG) and were administered the Pittsburgh Sleep Quality Index questionnaire (PSQI) and the Cystic Fibrosis Quality of Life Questionnaire (CFQR 14 + Spain). The study included 23 patients, 14 women (61%). The mean age of the participants was 32 + 18years. The mean PSQI score was 5.57 + 3.55; 13 (56.5%) of the patients were poor sleepers, and 13% reported poor sleep quality; seven (30%) had sleep latency > 30min, 10 (43.5%) had sleep efficiency < 85%. Nineteen underwent polysomnography. According to PSG measurements, sleep efficiency was less than 90% in 61% of the patients. Pathological values were found for the following parameters: intra-sleep wakefulness in 12 patients (63%); microarousal index in 12 patients (63%); and apnea-hypopnea index (AHI) in 2 patients. The desaturation time with SpO2 < 90% (T90) was > 30% in 3 patients. We observed a significant correlation between PSQI and all dimensions of CFQR 14. Subjective and objective sleep efficiency decreases in adult CF patients. Sleep quality has an impact on HRQoL. The PSQI questionnaire was able to discriminate sleep quality.

Increased Evoked Potentials to Arousing Auditory Stimuli during Sleep: Implication for the Understanding of Dream Recall.

High dream recallers (HR) show a larger brain reactivity to auditory stimuli during wakefulness and sleep as compared to low dream recallers (LR) and also more intra-sleep wakefulness (ISW), but no other modification of the sleep macrostructure. To further understand the possible causal link between brain responses, ISW and dream recall, we investigated the sleep microstructure of HR and LR, and tested whether the amplitude of auditory evoked potentials (AEPs) was predictive of arousing reactions during sleep. Participants (18 HR, 18 LR) were presented with sounds during a whole night of sleep in the lab and polysomnographic data were recorded. Sleep microstructure (arousals, rapid eye movements (REMs), muscle twitches (MTs), spindles, KCs) was assessed using visual, semi-automatic and automatic validated methods. AEPs to arousing (awakenings or arousals) and non-arousing stimuli were subsequently computed. No between-group difference in the microstructure of sleep was found. In N2 sleep, auditory arousing stimuli elicited a larger parieto-occipital positivity and an increased late frontal negativity as compared to non-arousing stimuli. As compared to LR, HR showed more arousing stimuli and more long awakenings, regardless of the sleep stage but did not show more numerous or longer arousals. These results suggest that the amplitude of the brain response to stimuli during sleep determine subsequent awakening and that awakening duration (and not arousal) is the critical parameter for dream recall. Notably, our results led us to propose that the minimum necessary duration of an awakening during sleep for a successful encoding of dreams into long-term memory is approximately 2 min.

Resting brain activity varies with dream recall frequency between subjects.

Dreaming is still poorly understood. Notably, its cerebral underpinning remains unclear. Neuropsychological studies have shown that lesions in the temporoparietal junction (TPJ) and/or the white matter of the medial prefrontal cortex (MPFC) lead to the global cessation of dream reports, suggesting that these regions of the default mode network have key roles in the dreaming process (forebrain 'dream-on' hypothesis). To test this hypothesis, we measured regional cerebral blood flow (rCBF) using [(15)O]H2O positron emission tomography in healthy subjects with high and low dream recall frequencies (DRFs) during wakefulness (rest) and sleep (rapid eye movement (REM) sleep, N2, and N3). Compared with Low recallers (0.5 ± 0.3 dream recall per week in average), High recallers (5.2 ± 1.4) showed higher rCBF in the TPJ during REM sleep, N3, and wakefulness, and in the MPFC during REM sleep and wakefulness. We demonstrate that the resting states of High recallers and Low recallers differ during sleep and wakefulness. It coheres with previous ERP results and confirms that a high/low DRF is associated with a specific functional organization of the brain. These results support the forebrain 'dream-on' hypothesis and suggest that TPJ and MPFC are not only involved in dream recall during wakefulness but also have a role in dreaming during sleep (production and/or encoding). Increased activity in the TPJ and MPFC might promote the mental imagery and/or memory encoding of dreams. Notably, increased activity in TPJ might facilitate attention orienting toward external stimuli and promote intrasleep wakefulness, facilitating the encoding of the dreams in memory.

Brain Reactivity Differentiates Subjects with High and Low Dream Recall Frequencies during Both Sleep and Wakefulness

The neurophysiological correlates of dreaming remain unclear. According to the "arousal-retrieval" model, dream encoding depends on intrasleep wakefulness. Consistent with this model, subjects with high and low dream recall frequency (DRF) report differences in intrasleep awakenings. This suggests a possible neurophysiological trait difference between the 2 groups. To test this hypothesis, we compared the brain reactivity (evoked potentials) of subjects with high (HR, N = 18) and low (LR, N = 18) DRF during wakefulness and sleep. During data acquisition, the subjects were presented with sounds to be ignored (first names randomly presented among pure tones) while they were watching a silent movie or sleeping. Brain responses to first names dramatically differed between the 2 groups during both sleep and wakefulness. During wakefulness, the attention-orienting brain response (P3a) and a late parietal response were larger in HR than in LR. During sleep, we also observed between-group differences at the latency of the P3a during N2 and at later latencies during all sleep stages. Our results demonstrate differences in the brain reactivity of HR and LR during both sleep and wakefulness. These results suggest that the ability to recall dreaming is associated with a particular cerebral functional organization, regardless of the state of vigilance.

Propriospinal myoclonus: A motor phenomenon found in restless legs syndrome different from periodic limb movements during sleep

Three patients presented with a 25-, 15-, and 5-year history of restless legs syndrome (RLS) and periodic limb movements during sleep (PLMS). For 1, 4, and 5 years, they reported additional involuntary trunk and limbs jerks preceding falling asleep and occasionally during intrasleep wakefulness. Videopolysomnography revealed jerks during relaxed wakefulness arising in axial muscles with a caudal and rostral propagation at a slow conduction velocity, characteristic of propriospinal myoclonus (PSM). Jerk-related EEG-EMG back-averaging did not disclose any preceding cortical potential. During relaxed wakefulness preceding falling asleep and during intrasleep wakefulness, PSM coexisted with motor restlessness and sensory discomfort in the limbs. PSM disappeared when spindles and K-complexes appeared on the EEG. At this time, typical PLMS appeared every 20 to 40 seconds, especially during light sleep stages. PLMS EMG activity was limited to leg, especially tibialis anterior muscles, and did not show propriospinal propagation. In one patient, alternating leg muscle activation was also present. Jerks with a PSM pattern represent another motor phenomenon associated with RLS and different from the more usual PLMS.

Propriospinal Myoclonus at the Sleep-Wake Transition: A New Type of Parasomnia

To describe the clinical, neurophysiological, and polysomnographic characteristics of propriospinal myoclonus (PSM) at the sleep-wake transition. Patients referred for insomnia due to myoclonic activity arising during relaxed wakefulness preceding sleep, or complaining of muscular jerks also during intrasleep wakefulness and upon awakening in the morning were considered. All patients underwent EEG-EMG recordings during wakefulness and night sleep. Back-averaging of the EEG activity preceding the jerks was performed. Somatosensory evoked potentials (SEPs), transcranial magnetic stimulation (TMS) and spinal and cranial MRI were also done. Four patients were studied all affected with involuntary jerks arising when falling asleep, and one with jerks also during sleep and upon awakening in the morning. N/A. Polysomnographic investigations revealed jerks arising during the sleep-wake transition period. Myoclonic activity was neurophysiologically documented to be of the propriospinal type. SEPs, TMS and MRI were normal PSM may have a peculiar relationship with the state of vigilance and represent a sleep-wake transition disorder. In this regard we consider PSM a new type of parasomnia.

Nocturnal polysomnography with and without continuous pharyngeal and esophageal pressure measurements.

PSG with simultaneous pharyngeal and esophageal pressure measurements of the upper airway may interfere with sleep architecture and cause a bias. The aim of this study was to evaluate the degree of disturbance to sleep caused by inclusion of pressure measurements of the airway, and whether this would reduce the validity of the PSG. Thirty-two consecutive patients referred for PSG for possible obstructive sleep apnea syndrome (OSAS) were included. For pressure recordings, a 6-F silicone tube, 1.9 mm in diameter, containing six pressure transducers, was introduced through one nostril into the pharynx and esophagus. Each patient had two nocturnal PSGs, one of which included airway pressure measurements. There were no statistically significant differences between PSGs performed with and without simultaneous pressure recordings for the following sleep quality parameters: total sleep time, number of sleep-stage shifts, sleep efficiency, arousal during sleep (= intrasleep wakefulness), percent REM sleep, and number of microarousals. We did not find any statistically significant differences for respiratory parameters such as type, duration, and index of different respiratory events and snoring. However, there was a slight tendency for reduced sleep quality and oxygen saturation when pressure measurements were included. The only significant change seen was in the duration of non-REM sleep with oxygen saturation below 90%. The multisensor airway pressure probe demonstrated that proximal obstructions were more common than distal obstructions, and obstruction in one or two segments was far more frequent than obstruction in more than two.

Modafinil, d-amphetamine and placebo during 64 hours of sustained mental work. II. Effects on two nights of recovery sleep.

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.

Ambulatory sleep–wake recording in an acclimatized mountaineer over 8 days at high altitude

Continuous ambulatory polygraphy (electroencephalogram and electrooculogram) was recorded on a 34-year-old female mountaineer acclimatized to an altitude of 5350 m, using a portable Oxford Medilog 9000 cassette recorder over 8 consecutive days. The recordings at altitudes of 5000 to 7600 m were performed while attempting to climb Mount Everest without an oxygen mask. The subject slept only at night. Altitude sleep measures were compared to data obtained at 300 m altitude during one 24-h recording performed before the expedition departed. The sleep–wake organization was barely influenced by altitude. Intrasleep wakefulness was augmented, leading to a decrease in sleep efficiency. No slow-wave-sleep curtailment was found, and day-to-day sleep–wake variations were more likely due to anxiety, fatigue owing to strenuous effort, nighttime cold, or daytime heat exposure.

Twelve months' follow-up by night sleep EEG after recovery from severe head trauma.

Night sleep EEG recordings were obtained in patients, 1, 6, and 12 months after recovery from severe head trauma with signs of brain stem dysfunction. Modifications of intra-sleep wakefulness (W.) and REM sleep were observed but none of slow wave sleep (SWS). At one month after regaining consciousness, the lower the initial level of brain stem dysfunction, the greater the sleep disturbances were. At six months, improvement was observed. At one year, sleep disturbances increased again mainly in patients between 35 and 45 years old. These results are best compared to those observed in normal but elderly people, over 70 years.