Original Research ARTICLE
Oscillatory EEG activity during REM sleep in elderly people predicts subsequent dream recall after awakenings
- 1Sapienza University of Rome, Italy
Several findings underlined that the electrophysiological (EEG) background of the last segment of sleep before awakenings may predict the presence/absence of Dream Recall (DR) in young subjects. However, little is known about the EEG correlates of DR in elderly people. Only an investigation found differences between recall and non-recall conditions during NREM sleep EEG in older adults, while –surprisingly- no EEG predictor of DR was found for what concerns REM sleep.
Considering REM sleep as privileged scenario to produce mental sleep activity related to cognitive processes, our study aimed to investigate whether specific EEG topography and frequency changes during REM sleep in elderly people may predict a subsequent recall of mental sleep activity.
Twenty-one healthy older volunteers (mean age 69.2 ± 6.07 SD) and twenty young adults (mean age 23.4 ± 2.76 SD) were recorded for one night from 19 scalp derivations. Dreams were collected upon morning awakenings from REM sleep. EEG signals of the last 5 min were analyzed by the Better OSCillation algorithm to detect the peaks of oscillatory activity in both groups.
Statistical comparisons revealed that older, as well as young individuals, recall their dream experience when the last segment of REM sleep is characterized by frontal theta oscillations. No Recall (Recall vs. Non-Recall) × Age (Young vs. Older) interaction was found. This result replicated the previous evidence in healthy young subjects, as showed in within- and between-subjects design. The findings are completely original for older individuals, demonstrating that theta oscillations are crucial for the retrieval of dreaming also in this population. Furthermore, our results did not confirm a greater presence of the theta activity in healthy aging. Conversely, we found a greater amount of rhythmic theta and alpha activity in young than older participants. It is worth to noting that the theta oscillations detected are related to cognitive functioning. We emphasize the notion that the oscillatory theta activity should be distinguished from the non-rhythmic theta activity identified in relation to other phenomena such as a) sleepiness and hypoarousal conditions during the waking state and b) the cortical slowing, considered as an EEG alteration in clinical samples.
Keywords: Dream recall, dreaming, Elderly, older adults, theta oscillations, REM sleep, EEG, Oscillatory activity
Received: 03 Jun 2019;
Accepted: 29 Aug 2019.
Copyright: © 2019 Scarpelli, D'Atri, Bartolacci, Mangiaruga, Gorgoni and De Gennaro. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Prof. Luigi De Gennaro, Sapienza University of Rome, Rome, Italy, email@example.com