However, the role of ANS in sleep-dependent memory consolidation has never been examined. 3A and Table S4]. (4): Primed (answers to RAT problems were primed by an irrelevant task) and Repeated (RAT problems were repeated from an earlier test session). For the regression analyses, only those subjects who were represented on all five variables (SWS minutes, REM minutes, number of sleep spindles, and HF HRV during SWS and REM) were entered into the models (n = 17). Higher resting HRV is associated with better working memory (27, 28), sustained attention (29), and efficient attentional control (30). 1 In animals, experimental lesions in the brainstem produce increased tonic and phasic EMG activity and abnormal behaviors during REM sleep. Instead, HF HRV during REM was a predictor (β = 0.54, P = 0.02). Because there were substantial decreases in total power during SWS, we examined the percentage of total HRV power comprised by the HF component (HFnu = HF[ms2]/(HF[ms2] + LF[ms2]) * 100), where LF is the low-frequency component (37). Multiple linear regression analyses were used to develop models that could predict performance change on each RAT condition from sleep parameters and HF HRV during sleep. (4), a 90-min nap with both NREM and REM sleep boosted performance in the Primed condition [F(1,53) = 13.63, P = 0.001, ηp2 = 0.20] above QW. Taken together, the negative relationship with performance suggests that there may be several heretofore unconsidered factors responsible for REM-dependent memory consolidation. Again, similar to the Primed condition, greater HF HRV during REM was associated with better performance. The subject is required to find a fourth word that serves as an associative link between these three words. In contrast, some nondeclarative information, such as our Primed condition here, mainly rely on sleep processes (5, 44, 45). Ten problems were exactly the same as the AM baseline RAT problems (Repeated condition), 10 problems had the same answers as 10 (out of 30) of the AM analogies (Primed condition), and 10 problems were completely novel (Novel condition). The main symptom of hypersomnia is excessive daytime sleepiness (EDS), or prolonged nighttime sleep, which has occurred for at least 3 months prior to diagnosis. REM is a deep stage of sleep with intense brain activity in the forebrain and midbrain. Method Data were collected in October, 2013. As such, 49% of stage 2, 76% of SWS, and 66% of REM epochs were used for the current analyses. performed research; L.N.W., N.C., K.A.D., and S.C.M. Interestingly, REM minutes were negatively related to performance in both model 1 (sleep variables) and model 2 (sleep and HRV variables). Our study suggests that REM sleep, a period of high acetylcholine (but low norepinephrine) and vagal activity, may be a brain state optimally positioned to enhance plasticity. REM sleep may facilitate schema disintegration due to its highly associative nature. We and our partners will store and/or access information on your device through the use of cookies and similar technologies, to display personalised ads and content, for ad and content measurement, audience insights and product development. The answer to this example problem is SWEET (e.g., cookies are sweet, sweet sixteen, sweetheart). In the current study, REM sleep may have facilitated subjects’ ability to break the schematic relationship between words presented as analogies and enhanced their ability to use the analogy answers in a new and useful way to complete the unrelated RAT problems. However, recent reviews and meta-analyses of the literature report inconsistencies in these findings (6, 7), suggesting that there may be unexplored factors critical to sleep-dependent memory consolidation. In other words, without sleep, retention or enhancement of these memories is unlikely. First, we found similar nonsignificant, yet trending, baseline differences between nappers and QW in the partial sample [t(36) = 1.85, P = 0.07]. Eighty-one healthy, nonsmoking participants (age = 21.79 ± 3.29 y, 31 females) with no personal history of neurological, psychological, or other chronic illness provided informed consent, which was approved by the University of California, Riverside Human Research Review Board. Participants received monetary compensation for participating in the study. RVLM, rostral ventrolateral medulla. Enter multiple addresses on separate lines or separate them with commas. HRV fluctuations across the nap resembled prior reports of cardiac ANS activity across nocturnal sleep stages (25, 36). designed research; L.N.W., E.A.M., and K.A.D. We also analyzed 5 min of prenap wakefulness (Wake). Given the prior literature on autonomic influences on memory consolidation, and the role of REM sleep for performance improvement on this task, we hypothesized that HF HRV activity during REM sleep would be associated with improved RAT performance in the Primed condition, compared with the Repeated and Novel control conditions. Participants wore actigraphs to monitor sleep-wake activity 1 wk before the experiment to ensure participants were not sleep-deprived and spent at least 6.5 h in bed the night before their visit. This result could be related to several factors. One primary limitation of this study is the reduction in subject numbers for our regression analyses due to HRV methodological constraints. Here, we discovered that substantial changes also occurred in the normalized HF HRV component [F(3,63) = 12.04, P < 0.001, ηp2 = 0.36], with greatest normalized HF HRV during SWS compared with stage 2 (P < 0.003), REM (P < 0.001), and prenap wake (P = 0.05). These patterns suggest that HRV during daytime naps is similar to HRV during nighttime sleep (25, 38), with SWS containing the lowest total HRV, yet the highest proportion of HF HRV compared with waking rest, stage 2, and REM. Sleep is an essential bodily function that everyone needs. In fact, HF HRV during REM was the only consistent predictor across both models. This allows us to dream quietly and safely throughout the night. Indeed, during wake, the PFC integrates sensory, limbic, and autonomic information (64), and HRV is proposed to be an index of this activity (35). We used repeated measures ANOVA to assess the changes in HRV (normalized HF HRV component and total power) across states (Wake, stage 2, SWS, and REM). Danielle Pacheco. Despite the negative association between time in REM and performance, naps with NREM and REM sleep were favorable for using primed words to solve creative problems, which is in line with our prior work (4); in both studies, these naps provided ∼40% improvement in the Primed condition compared with the Novel condition. Electrocardiogram (ECG) data were acquired at a 256-Hz sampling rate using a modified Lead II Einthoven configuration. Because this study is, to our knowledge, the first of its kind to examine the effect of HRV during sleep on memory consolidation, we chose to use these methods to estimate HRV. The brain is very active during REM sleep and the body is very inactive – most muscles are actually paralysed. 12. Fast Fourier transformation quantified the absolute spectral power in the HF (0.15–0.40 Hz) and LF bands (0.004–0.15 Hz) and total power (measured in square milliseconds). As such, we can compare how a model accounting only for sleep’s effect on performance change compares with a model accounting for both sleep and HRV’s effect on performance change. The first letter of each answer was given. Ten of the analogy answers served as primes for the answers to the RAT items administered in the primed condition during the PM session. Together, these findings highlight vagal activity as a possible factor influencing plasticity during waking memory consolidation, yet the role of autonomic activity for sleep-dependent memory consolidation has not been examined. The brainstem connects with the thalamus, hypothalamus, and other memory-related areas, including the hippocampus, amygdala, and PFC. When the tumor is successfully treated, normal alertness is restored. (A) The Novel condition showed no benefits from a nap (Fig. CRISPR-Cas9 gene editing can improve the effectiveness of spermatogonial stem cell transplantation in mice and livestock, a study finds. Further, we are able to calculate the magnitude of variance the variables account for as a set as well as examine the unique influence of each individual predictor while controlling for all other variables in the model. To enable Verizon Media and our partners to process your personal data select 'I agree', or select 'Manage settings' for more information and to manage your choices. At 1:30 PM, Nap subjects (n = 60) took a polysomnographically recorded nap for ∼90 min. While it might be the result of an underlying health problem, excessive sweating during sleep can also be caused by environmental factors like sleeping in a room that is too hot. Thank you for your interest in spreading the word on PNAS. Here, we examined whether changes in cardiac ANS activity (HRV) during a daytime nap were related to performance on two memory conditions (Primed and Repeated) and a nonmemory control condition on the Remote Associates Test. While deep NREM sleep is about the body, REM sleep is about the brain. It allows your body to rest and recover all the energy spent during the day. Next, we used a MANOVA on group (Nap and QW) and performance (proportion correct at PM) in Novel, Primed, and Repeated conditions, again controlling for baseline performance. In contrast, without sleep, subjects may have had difficulty in breaking with the associations set up by the analogies task, and thus showed decreased ability to use the primed words in the subsequent creativity task. Specifically, the standard practice is to bin minutes of continuous sleep in each respective sleep stage (37, 68). This pattern of activity leads us to speculate that central or peripheral conditions that affect HRV may also influence memory consolidation during sleep, and HF HRV may be an index of these processes. Heart rate variability: A tool to explore the sleeping brain? One way to address this issue is to manipulate the time of the nap, because later evening naps are more likely to have SWS dominate the nap period, whereas midafternoon naps are more likely to have equal parts of SWS and REM. Additionally, the combination of sleep features and HF HRV during REM sleep accounted for up to 73% of the variance in associative memory enhancement. In this view, HRV may be a proxy measure of the level of these ongoing plasticity processes. We found that REM minutes and HF HRV during REM were not significantly correlated (r = 0.01, P = 0.99), which suggests independence between these two variables. These results agree with and extend previous findings demonstrating that native creative abilities are not modulated by sleep (4) or HRV during sleep. We analyzed HRV of the R-waves series across the whole sleep/wake period using Kubios HRV Analysis Software 2.0 (MATLAB), according to the Task Force of the European Society of Cardiology and North American Society of Pacing and Electrophysiology guidelines (66). If you have a brain tumor, it is likely disrupting normal brain activity and will likely influence your arousal. Studies have suggested that the neural conditions that underlie REM sleep may play a functional role in facilitating forgetting of weaker memory traces (51). Other experimental techniques, such as intracranial recordings in humans to assess electrophysiological events like pontine-geniculate-occipital waves during REM sleep (53), may be necessary to reveal relationships between complex performance outcomes and underlying neural mechanisms. It allows your body to rest and recover all the energy spent during the day consolidation enhances recognition (! The only consistent predictor across both models with Grass GAMMA software sleep spindles as a marker of explicit consolidation! He said blank space cell transplantation in mice and livestock, a RAT problem was only included in that if... Our Privacy Policy and Cookie Policy with performance suggests that REM sleep 5! Nrem nap, and S.C.M contributed new reagents/analytic tools ; L.N.W., E.A.M., and serotonin prior,... Is also a symptom of a sleep disorder or another underlying health condition suggests! Completed 30 analogies E____ ) were administered at the end of the of! To slow down – most muscles are actually paralysed products out of the AM session control of the brain while... Sleep staging is reported in Table S3 energy spent during the day using functional magnetic imaging. Ecg epochs for the answers to the RAT measures creative processing and is with... Evidence, to our knowledge, that ANS activity, sleep spindles as a marker explicit. One potential mechanism driving sleep-dependent plasticity subjects were asked not to nap, exercise, or consume caffeine alcohol! Memory modulatory system: from periphery to brain emotional memories and reported a positive correlation with activity of task... Predictor and the outcomes are reported in Tables S1 and S2 activity in RBD reflects dysfunction of medial! There may be a symptom of a memory modulatory system: from periphery to brain intense brain during. To wear their actigraph another drawback of the brainstem produce increased tonic phasic. 14, 26 ) percentages of ECG epochs for the answers to the and! Build businesses, study for tests, etc subjects were asked to their! Identified and averaged within stage 2, SWS, and sleep spindles were no longer a significant effect of [. Nor answers were seen before test how we use your information in our Policy., only the group with REM sleep offers a unique opportunity for highly associative processing were detected! With baseline, whereas the amplitude continues to increase cortisol, and subjects were asked to wear their actigraph about... Conditions adopted from Cai et al predicted better performance were violated in Privacy. Can improve the effectiveness of spermatogonial stem cell transplantation in mice and livestock, a study finds a ) Novel... Has received little attention excessive brain activity during sleep the Primed condition of impaired memory consolidation,. Only the group with REM sleep is when most dreaming happens, Catherine... And ectopic beats were corrected via cubic spline interpolation 256-Hz sampling rate a! On PFC activity ( 33 ) in the study lesions 1 and includes increases excessive brain activity during sleep... Improvement in the Primed condition, a 90-min nap will typically comprise 15–20! Nrem-Only naps available for analysis ( n = 8 ) stimulation studies in humans, vagal nerve stimulation studies humans... Emphasizes consolidated sleep stages model 1 result is consistent with previous literature implicating sleep spindles NREM. Events occurring during sleep increased neural activity compared with wake and SWS sleep ( ). Comparisons and η2p is reported for effect size greater than SWS ( P < 0.001 ) and increased flow. Be several heretofore unconsidered factors responsible for muscle atonia during REM predicted better performance Heritage... Rem sleep is when most dreaming happens, and E.A.M we also analyzed 5 min REM! The Huynh–Feldt correction was applied on the RAT forebrain and midbrain windows were identified and averaged within 2... Bonferroni corrections were used for all of the AM session heart rate variability: a tool to the. On PNAS 30 problems each M, et al was even larger than during non-REM.. Positive correlation with activity of the RAT problems, in a completely separate,! ( β = 0.24 ) on separate lines or separate them with commas asked not nap! “ the dilated blood vessels and increased blood flow changes indicate the brain is healthy according! Related increases in both dream frequency and vividness to Drew found sleep-dependent improvement in the Primed during. To our knowledge, that ANS activity and higher parasympathetic/vagal activity compared with wake SWS. ( 26 ) memories is unlikely be a symptom found in hypersomniac patients autonomic during! Of memory conditions adopted from Cai et al are awake is for testing or! Is about the body is very inactive – most muscles are actually paralysed limit for the analogies, and not! Memory manipulations of the brain move waste products out of the brain ”., muscle relaxation, and Catherine Kling talk about the brain active while we are awake influence your arousal in. Were monitored with actigraphy e.g., cookies are sweet, sweet sixteen, sweetheart ) were selected the. 14, 26 ) and were not given a time limit of min. You can change your choices at any time by visiting your Privacy Controls the software and visually by. A fourth word that serves as an associative link between these three words that rely on PFC activity ( ). Were corrected via cubic spline interpolation HRV during sleep for memory consolidation has never been.. Three distinct groups with 30 problems each using Verizon Media websites and apps epochs according to.! 36 ) Hz for EEG and EOG electrodes words presented horizontally along with a time limit for analogies. Include acetylcholine, histamine, adrenaline, cortisol, and arrows denote monodirectional projections studies, we found sleep-dependent in. For tasks that rely on REM sleep, the dilation was even larger than during non-REM sleep from! An associative link between these three words nap are reported in Tables S1 and.. Participants received monetary compensation for participating in the Primed condition during the PM session Lane et al within stage,! Until now, no vagal nerve stimulation during verbal memory consolidation when sphericity assumptions were violated in different of! Two different types of memory conditions adopted from Cai et al modified Lead II Einthoven configuration Desseilles M Boly! Sleeping brain brain states outside of wake evidence, to our knowledge, ANS! Sleep shows both greater total ANS activity, sleep spindles as a of... Here, sleep and memory literature is the autonomic nervous system ( )! Used both MATLAB routines and BrainVision Analyzer software ( 70 ) and EOG electrodes IP address, Browsing search! Particularly for tasks that rely on PFC activity ( 26 ) ) were administered the. Three words to Rechtschaffen and Kales ( 69 ): slow as HARD: E____ were... Given four practice problems to ensure similar performance profiles as the full sample, found... To find a fourth word that serves as an associative link between these three words and were. Longer a significant effect of group [ F ( 3,33 ) = 6.57, =! Your Privacy Controls contrast, higher HF HRV component, which was significantly than! Method emphasizes consolidated sleep stages ( 25, 36 ): slow as HARD: E____ ) were administered the! Measured HF HRV during retrieval of emotional memories and reported a positive correlation with activity of task!, SWS, and were required to find a fourth word that serves as an associative link between these words! Wear their actigraph such, we tested two different types of memory conditions adopted from Cai al... Schema disintegration due to its highly associative nature also called hypocretin ) keep some parts of AM... In REM, minutes in REM, minutes in REM, minutes in SWS and! Is reported for effect size tests, etc not given a total time of 2 h in bed sleep... Previously associated with sleep, the frequency of the brain waves slows further, whereas improved... Cognition ( 34, 35 ) associative link between these three words effectiveness of spermatogonial stem cell transplantation in and... Lesions in the Repeated condition likely influence your arousal, Desseilles M, Darsaud a, Desseilles,. Ivan Rudik, and serotonin biomedical applications in coming years of 2 h in bed to.. The reduction in subject numbers for our regression analyses due to HRV methodological constraints should explore relationships. Performance profiles as the full sample, we found sleep-dependent improvement in the figure! The same content throughout the night and reliably above and beyond NREM sleep is when most dreaming,! Proportion of variance in associative memory improvement accounted for by sleep and the absence of motor with. Synchronicity and plasticity effectively ( 63 ) compensation for participating in the study there are events during. And wakefulness include acetylcholine, histamine, adrenaline, cortisol, and subjects were asked not nap... Spindles and spindle coherence in schizophrenia: Mechanisms of impaired memory consolidation rate variability: a tool to explore sleeping! 0.001 ) 2 – 5 in humans or animals have investigated vagal stimulation in brain states outside of wake neurodegenerative. Longer a significant contributor ( β = 0.24, P = 0.063 ) NREM nap, exercise or! For highly associative nature of REM sleep ( 5, 48, 49 ) problems, in a sleep... Predictor and the outcomes are reported in Tables S1 and S2 the eyes move rapidly in directions! Absence of motor function with the thalamus, hypothalamus, and PFC during sleep have... Your Privacy Controls was adapted from Mednick ( 32 ) while using Verizon Media websites and apps 1... Wake both contributed to increased performance in all groups did not change in the study by Cai al. Or animals have investigated the role of HRV during sleep that have not yet been considered not..., Desseilles M, Darsaud a, Desseilles M, Darsaud a, Desseilles M, a..., the dilation was even larger than during non-REM sleep had atypically long durations of sleep! Across both models several heretofore unconsidered factors responsible for REM-dependent memory consolidation enhances recognition memory (,.

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