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The study of electroencephalographic (EEG) signals in nonhuman primates has led to important discoveries in neurophysiology and sleep behavior. Several studies have analyzed digital EEG data from primate species with prehensile tails, like the spider monkey, and principal component analysis has led to the identification of new EEG bands and their spatial distribution during sleep and wakefulness in these monkeys. However, the spatial location of the EEG correlations of these new bands during the sleep-wake cycle in the spider monkey has not yet been explored. Thus, the objective of this study was to determine the spatial distribution of EEG correlations in the new bands during wakefulness, rapid eye movement (REM) sleep, and non-REM sleep in this species. EEG signals were obtained from the scalp of six monkeys housed in experimental conditions in a laboratory setting. Regarding the 1-21 Hz band, a significant correlation between left frontal and central regions was recorded during non-REM 2 sleep. In the REM sleep, a significant correlation between these cortical areas was seen in two bands: 1-3 and 3-13 Hz. This reflects a modification of the degree of coupling between the cortical areas studied, associated with the distinct stages of sleep. The intrahemispheric EEG correlation found between left perceptual and motor regions during sleep in the spider monkey could indicate activation of a neural circuit for the processing of environmental information that plays a critical role in monitoring the danger of nocturnal predation., (© 2023 Wiley Periodicals LLC.)

It has been reported that melatonin diminishes rapid eye movement (REM) sleep latency in patients with Alzheimer's disease (AD). Pharmacological studies suggest that melatonin promotes prompt sleep installation through interaction with GABA receptors, and that it is associated with acute suppression of neural electrical activity. Nevertheless, melatonin's effects on electroencephalographic (EEG) activity related to REM sleep onset in AD patients have not been analyzed. Thus, in this pilot study we analyzed the effects of melatonin on EEG activity during the first episode of REM sleep in eight patients treated with 5-mg of fast-release melatonin., During a single-blind, placebo-controlled study, polysomnographic recordings were obtained from frontal, central, temporal, and occipital scalp derivations. REM sleep latency, as well as the relative power (RP) and EEG coherences of six EEG bands, were compared between the placebo and melatonin conditions., Results showed that melatonin intake in AD patients decreased REM sleep onset, and that this was associated with lower RP and coherence of the β and γ EEG bands., The possibility that the inhibitory GABAergic pathways related to REM sleep generation are well-preserved in mild-to-moderate AD is discussed. We conclude that the short REM sleep onset related to melatonin intake in AD patients is associated with a significant decrease in both RP and EEG coherence, mainly in the fast frequencies.

Although motor activity is actively inhibited during rapid eye movement (REM) sleep, specific activations of the facial mimetic musculature have been observed during this stage, which may be associated with greater emotional dream mentation. Nevertheless, no specific biomarker of emotional valence or arousal related to dream content has been identified to date. In order to explore the electromyographic (EMG) activity (voltage, number, density and duration) of the corrugator and zygomaticus major muscles during REM sleep and its association with emotional dream mentation, this study performed a series of experimental awakenings after observing EMG facial activations during REM sleep. The study was performed with 12 healthy female participants using an 8-hr nighttime sleep recording. Emotional tone was evaluated by five blinded judges and final valence and intensity scores were obtained. Emotions were mentioned in 80.4% of dream reports. The voltage, number, density and duration of facial muscle contractions were greater for the corrugator muscle than for the zygomaticus muscle, whereas high positive emotions predicted the number (R 2 0.601, p = 0.0001) and voltage (R 2 0.332, p = 0.005) of the zygomaticus. Our findings suggest that zygomaticus events were predictive of the experience of positive affect during REM sleep in healthy women., (© 2018 European Sleep Research Society.)

Introduction: It is a well-known fact that epileptic seizures disrupt sleep, yet little information is available about sleep disorders according to the type of epileptic seizures., Materials and Methods: The sleep architecture of rats was evaluated in polysomnography recordings 36 hours after inducing partial and generalised epileptic seizures in them. The epileptic seizures were induced by applying 50-100 IU of sodium G penicillin in the amygdala of the temporal lobe., Results: Partial and generalised seizures triggered an increase in the latency of slow wave sleep (SWS) and rapid eye movement (REM) sleep. The number of episodes of the phases of wakefulness, SWS and REM sleep was reduced and the mean duration of the episodes of wakefulness and SWS increased, while that of REM sleep diminished. The total percentage of REM sleep diminished significantly. During the first period of light the partial and generalised seizures triggered an increase in wakefulness and a reduction in the phases of SWS and REM sleep. In the period of darkness, the SWS increased and wakefulness decreased, while there were no changes in REM sleep. In the second period of light, the percentages of the phases of wakefulness and SWS returned to control values and the percentage of REM sleep continued to be reduced., Conclusions: Changes in the structuring of sleep depend on the type of epileptic seizure that presents. Generalised epileptic seizures caused greater deterioration in REM sleep.