REM Density Research Articles

Lucid dreaming occurs in activated rapid eye movement sleep, not a mixture of sleep and wakefulness.

(1) To critically test whether a previously reported increase in frontolateral 40 Hz power in lucid REM sleep, used to justify the claim that lucid dreaming is a "hybrid state" mixing sleep and wakefulness, is attributable to the saccadic spike potential (SP) artifact as a corollary of heightened REM density. (2) To replicate the finding that lucid dreams are associated with physiological activation, including heightened eye movement density, during REM sleep. (3) To conduct an exploratory analysis of changes in EEG features during lucid REM sleep. We analyzed 14 signal-verified lucid dreams (SVLDs) and baseline REM sleep segments from the same REM periods from six participants derived from the Stanford SVLD database. Participants marked lucidity onset with standard left-right-left-right-center (LR2c) eye-movement signals in polysomnography recordings. Compared to baseline REM sleep, lucid REM sleep had higher REM density (β = 0.85, p = 0.002). Bayesian analysis supported the null hypothesis of no differences in frontolateral 40 Hz power after removal of the SP artifact (BH = 0.18) and ICA correction (BH = 0.01). Compared to the entire REM sleep period, lucid REM sleep showed small reductions in low-frequency and beta band spectral power as well as increased signal complexity (all p < 0.05), which were within the normal variance of baseline REM sleep. Lucid dreams are associated with higher-than-average levels of physiological activation during REM sleep, including measures of both subcortical and cortical activation. Increases in 40 Hz power in periorbital channels reflect saccadic and microsaccadic SPs as a result of higher REM density accompanying heightened activation.

Sleep EEG Signatures in COVID-19 Survivors.

Study ObjectivesEffect of COVID-19 on sleep architecture is not known. This study was done to find out EEG changes seen during sleep in COVID-19 survivors.MethodologyIn this prospective single centre study, consecutive patients diagnosed with RTPCR confirmed COVID 19 were included after 4–6 weeks of discharge from hospital. All patients underwent level I PSG. EEG was analysed for presence of abnormal EEG pattern.ResultsTotal 189 patients were contacted telephonically for participation in this study. Finally 81 patients (55 males, 26 females) underwent Level I PSG. Total sleep time was 345.1 ± 85.1 min. Sleep efficiency was 76.0 ± 14.2%. Mean time (%) during N1, N2, N3 and Rapid Eye movement (REM) was 16.4%, 59.2%, 7.9% and 18.4% percentage, respectively. Mean AHI was 28.7 ± 22.8 per hour and arousal index was 23.9 ± 13.3. Alpha intrusion was the most common EEG finding (78%), followed by cyclical alternating pattern (59%). REM density was significantly increased in 38% of patients. REM alpha bursts and increased spindles were also seen in 27% and 16%.ConclusionAbnormal EEG waves are very commonly seen in COVID-19 survivors. Presence of these abnormal PSG-EEG waves hints that COVID-19 might have similar effects as depression, insomnia on these subjects, at least in short run. Whether these changes are temporary or permanent needs to be evaluated by performing serial polysomnographies in patients with COVID-19 ARDS.

P120 The Relationship Between Sleep Architecture And Cognition In Late-Life Depression

Abstract Introduction Depression in older people is associated with changes in sleep, however associations between sleep architecture and cognition have not yet been delineated. We examined sleep architecture in older people with and without depressive symptoms, and relationships with neuropsychological performance. Methods Adults over 50 years underwent overnight polysomnography and memory and executive function tests. Depression and controls groups were defined by a Geriatric Depression Scale-15 cut off score of 6. Sleep architectural outcomes included amount of slow wave sleep (SWS), rapid eye movement (REM) sleep, REM onset latency (ROL), NREM slow wave activity (SWA, 0.5–4 Hz), N2 sleep spindle density and REM density. Results The sample comprised of 71 participants with depressive symptoms and 101 controls (mean age both groups = 64, mean GDS-15 dep= 9.3, con= 1.8). There were no significant group differences in time spent in SWS, REM, REM density or SWA. Those with depressive symptoms had later ROL (p=.008) and less N2 sleep spindles (p=.03) compared to controls. A differential association was observed with less SWS being associated with poor memory recall in the depression group only (z=.342, p=0.008). No associations between sleep and executive function performance were observed. Discussion The link between less time in SWS and poorer memory in those with depressive symptoms could suggest that SWS is particularly pertinent for cognition in depression or that both sleep and cognition mechanisms are influenced by depressive state. Further studies are needed to determine if changes in sleep are linked with underlying neurobiological changes.

Evaluation of Erectile Dysfunction in Nonobese, Nondiabetic Men with Obstructive Sleep Apnea

Background: Erectile Dysfunction (ED) has affected people suffering from Obstructive Sleep Apnea Syndrome (OSAS) and multiple studies have confirmed this correlation. Objective: The objective of the is to identify the association between ED and Obstructive Sleep Apnea (OSA) in nonobese, nondiabetic men based on the International Index of Erectile Function (IIEF). Methods: This retrospective cross-sectional study included 143 nonobese, nondiabetic men with OSA (age, ≥20 years) who visited the Sleep Outpatient Clinic of the Otorhinolaryngology Department at Hospital Naval Marcílio Dias from May 2017 to August 2018. Patient age, body mass index (BMI), drinking, smoking, laboratory diagnosis of hypogonadism based on total testosterone levels, and sleep parameters (e.g., apnea–hypopnea index, rapid eye movement density, and minimum Oxygen Saturation [SatO2]) were considered. Analysis of variance was used to evaluate means. The chi-squared test and Fisher’s exact test were used to compare variables and Person’s correlation coefficient was used to analyze numerical variables. Results: The mean minimum SatO2 was 78.89%, and 46% of patients exhibited minimum SatO2 &lt;80%. Moreover, minimum SatO2 of &lt;80% and increasing age were associated with ED complaints based on IIEF scores,. A laboratory diagnosis of hypogonadism was associated with increased BMI, and aging was associated with SatO2. Conclusion: The results of the study revealed that oxygen desaturation of &lt;80% was related to complaints of ED from the IIEF. Moreover, a relationship between laboratory hypogonadism and increased BMI values, aging, and oxygen desaturation has been demonstrated. Therefore, we recommend polysomnography in patients with ED complaints.

REM sleep without atonia and nocturnal body position in prediagnostic Parkinson's disease

BackgroundSleep disturbances are features of Parkinson's disease (PD), that can already occur before PD diagnosis. The most investigated prodromal PD sleep disorder is REM sleep behavior disorder (RBD). The relation between other polysomnographic (PSG) alterations and the prediagnostic stages of PD, however, is less clear. MethodsWe performed a retrospective case–control study to characterize polysomnographic alterations in PD and prediagnostic PD. We included 63 PD subjects (33 subjects that underwent a video-PSG before PD diagnosis [13 with and 20 without RBD] and 30 subjects that underwent a PSG after PD diagnosis) and 30 controls. PSGs were analyzed for sleep stages, different RSWA variables, body position, arousals, periodic limb movements, and REM density. ResultsHigher subscores of all RSWA variables were observed in subjects with PD and prediagnostic PD (with and without RBD). Total RSWA, tonic RSWA and chin RSWA severity were significant predictors for all PD and prediagnostic PD groups. Our study also shows a higher percentage of nocturnal supine body position in all PD and prediagnostic PD groups. Supine body position percentage is the highest in the PD group and has a positive correlation with time since diagnosis. ConclusionsThese findings suggest that increased total, tonic and chin RSWA as well as nocturnal supine body position are already present in prediagnostic PD, independently of RBD status. Prospective longitudinal studies are necessary to confirm the additional value of these PSG abnormalities as prodromal PD biomarkers.

Electrophysiological Evaluation in Identifying Unique Sleep Features Among Anti-LGI1 Encephalitis Patients During Active and Recovery Phase.

ObjectiveThe purpose of this study was to illustrate the electrophysiological features of sleep disturbances in patients with anti-leucine-rich glioma-inactivated protein 1 (anti-LGI1) encephalitis in both active and recovery stages.MethodsRetrospectively filed video electroencephalogram (VEEG) and polysomnography (PSG) data in 24 patients with anti-LGI1 encephalitis were analyzed in comparison with that in 20 individuals without sleep disorders as control group.ResultsSleep efficiency (SE) and total sleep time involving REM and NREM sleep were significantly decreased in patients with anti-LGI1 encephalitis during the active stage compared to that during the recovery stage and in the control group. Imbalanced sleep structure was found, demonstrated by elevated N1, decreased N3 and REM components, as well as abnormal N2 structure characterized with significantly lower spindle duration and density during the active stage. These findings were independent of the presence of nocturnal episodic events or sleep hyperkinetic movements (HMs). HMs were present in 11/23 patients throughout NREM and REM sleep (nonspecific in sleep stages) during the active stage. During the recovery stage, SE and sleep structures were dramatically improved, including the percentage of N3 and REM sleep, spindle duration and density. Ten of 11 patients with HMs were followed up. HMs were totally remitted in 3 patients and still persistent in 1, while evolved into REM sleep behavior disorder (RBD) in 4 with comorbid periodic limb movement syndrome (PLMS) in 3/4, and only PLMS in 2.ConclusionSleep disturbances were remarkable and intrinsic features in active anti-LGI1 encephalitis, marked by overall disruptions of both NREM and REM sleep, as well as the presence of HMs, which tend to evolve into RBD or PLMS during the recovery stage. Long-term follow-up with PSG is needed, especially for those patients with severe sleep disturbances during the active phase.

Sleep parameters improvement in PTSD soldiers after symptoms remission

Eye movement desensitization and reprocessing (EMDR) is a psychotherapy for the treatment of posttraumatic stress disorder (PTSD). It is still unclear whether symptoms remission through EMDR therapy is associated with a beneficial effect on one of the PTSD symptoms, sleep disturbance. Our objective was therefore to study sleep parameters before and after symptom remission in soldiers with PTSD. The control group consisted of 20 healthy active duty military men who slept in a sleep lab with standard polysomnography (PSG) on two sessions separated by one month. The patient group consisted of 17 active duty military with PTSD who underwent EMDR therapy. PSG-recorded sleep was assessed 1 week before the EMDR therapy began and 1 week after PTSD remission. We found that the increased REMs density after remission was positively correlated with a greater decrease of symptoms. Also, the number of EMDR sessions required to reach remission was correlated with intra-sleep awakenings before treatment. These results confirm the improvement of some sleep parameters in PTSD after symptoms remission in a soldier's population and provide a possible predictor of treatment success. Further experiments will be required to establish whether this effect is specific to the EMDR therapy.

Automatic Onset Detection of Rapid Eye Movements in REM Sleep EEG Data

Abstract Rapid eye movements (REM) during sleep is a descriptor of the REM sleep stage. Parameters associated with REM sleep, such as REM sleep numbers, REM density, REM latency, and pre-REM negativity have been associated with the functional role of REM sleep. The temporal properties of these parameters appear to play an essential role in REM sleep, so precise knowledge of these temporal properties, particularly REM onset, can help elucidate the temporal dynamics of neural activity related to REM sleep. However, manual detection of this event is a time-consuming and subjective process that can be facilitated by an automatic detection tool. We developed an automatic REM onset detection algorithm based on features describing rapid eye movements and compared the results obtained with human detection by a sleep expert.

REM density is associated with treatment response in major depression: Antidepressant pharmacotherapy vs. psychotherapy

Major depression is one of the most common psychiatric illnesses. Interestingly, a few studies have indicated the existence of depression subgroups, which respond differently to the available treatment options. Previously, sleep abnormalities have been suggested to indicate amenability to different treatment regimens. Thereby, especially REM-sleep parameters seem to play a prominent role, and REM-sleep dysregulation has been repeatedly discussed as a potential endophenotype of depression. With that said, estimating therapy outcome in order to choose the best line of treatment is of utmost importance to patients suffering from depression.The present study looks deeper into these clues by investigating the capability of polysomnographic sleep parameters to predict treatment response in depressed patients to either pharmacotherapy or psychotherapy. Moderately to severely depressed patients (n = 38) were randomly assigned to either psychotherapy (i.e. interpersonal psychotherapy) or pharmacotherapy (i.e., monotherapy with selective serotonin reuptake inhibitors, SSRI, or selective serotonin noradrenalin reuptake inhibitors, SSNRI). Prior to treatment, all patients underwent polysomnography in the sleep laboratory. After treatment, responders and non-responders of both treatment groups were compared regarding their baseline sleep parameters.Higher baseline REM density, i.e. the amount of rapid eye movements during REM sleep, predicted better response to antidepressant pharmacotherapy. In the psychotherapy group, the effect seemed reversed but was not statistically significant. No other sleep parameter predicted treatment response.Our findings support the notion that REM-sleep dysregulation is indeed indicative of a distinct endophenotype of depression and that pharmacotherapy with SSRI/SSNRI might be superior to psychotherapy in these patients.

The association between emotional dysregulation and REM sleep features in insomnia disorder

Rapid Eye Movement (REM) sleep is involved in nightly emotional processing; therefore, its disruption might be associated with an impaired ability of emotional regulation during daytime. Accordingly, the aim of the present study was to evaluate the presence of emotional dysregulation in insomnia patients and to test its correlation with REM sleep features. Forty-six subjects (23 insomnia patients and 23 healthy controls) were enrolled. All subjects underwent an assessment for the evaluation of emotion dysregulation (Difficulties in Emotion Regulation Scale, DERS), sleep quality, insomnia severity, excessive daytime sleepiness, worry, rumination, depressive and anxious symptomatology. Insomnia patients underwent a nocturnal polysomnographic recording to characterize sleep macrostructure and REM sleep microstructure variables. Insomnia patients reported increased values of emotional dysregulation. REM sleep percentage and REM sleep latency significantly correlated with DERS total score, and with the subscales “Lack of Confidence in Emotional Regulation Skills”, “Difficulties in Behavioral Control” and “Difficulty in recognizing emotions”. Furthermore, positive correlations between REM arousal index and emotion dysregulation were found, whereas REM density negatively correlated with DERS. Our results suggest the presence of a relationship between REM sleep and emotional regulation in insomnia patients.

Polysomnographic phenotype of isolated REM sleep without atonia

ObjectiveIsolated REM sleep without atonia (iRSWA) is regarded as a prodromal phase of REM sleep behavior disorder and synucleinopathies. In iRSWA patients, we investigated the polysomnographic characteristics that are known to be altered in (prodromal) Parkinson’s disease (PD): periodic limb movements of sleep [PLMS] (increased), REM density (reduced), and heart rate variability ([HRV] (reduced). MethodsWe compared video-polysomnographic studies of 49 iRSWA subjects with 41 controls. RSWA and PLMS were scored visually. REM density (REM/hour) and HRV were calculated automatically. ResultsWe found a higher median total (15.90 vs 7.20; p = 0.001), REM (21.80 vs 11.0; p < 0.001) and non-REM (11.75 vs 5.72; p = 0.027) PLMS index, and a higher mean REM density (342.45 vs 275.96; p = 0.010) in the iRSWA group, with a significant positive correlation between RSWA severity and these variables (r = 0.39; p < 0.00, r = 0.48; p < 0.001, r = 0.24; p = 0.021, r = 0.28; p = 0.012). We found no significant difference in HRV between groups. ConclusionsOur results suggest an association between RWSA and REM density and PLMS, but not HRV. The positive correlation between these variabilities may imply overlapping pathophysiological processes. SignificanceThe evidence of higher REM density and normal HRV weakens the hypothesis that iRWSA is a prodromal PD stage. An alternative interpretation is, however, that REM density and HRV change during caudal-rostral neurodegeneration.

Increased rapid eye movement density in Chinese patients with Parkinson's disease and RBD.

Impaired rapid eye movement sleep is common among patients with Parkinson's disease (PD). However, information on rapid eye movement density (REM) among PD patients is currently lacking. The current study sought to characterize REM density in PD patients and to examine the associations between REM density sleep parameters and clinical manifestations. We retrospectively recruited 172 PD patients. All participants were assessed with a two-night polysomnography, and REM density was calculated. Clinical assessments were completed in PD patients before polysomnography. Rapid eye movement sleep behavior disorder (RBD) was observed in 93 patients (54.1%). The disease duration, UPDRS part III score, Hoehn and Yahr (H-Y) stage, and HAMA, HAMD, PDQ-39 scores, and REM density in the Parkinson's disease patients with rapid eye movement sleep behavior disorder (RBD) were significantly higher than in the patients without RBD (P < 0.05). However, NREM sleep stage 3 time (N3 time) and percentage of N3 time of total sleep time (N3%) were significantly lower in the RBD patients than in the patients without RBD (P < 0.05). The forward binary logistic regression model showed that REM density, UPDRS-III score, and N3 sleep time were associated with RBD in the PD patients. Our results confirm the high prevalence of RBD in patients with PD. Increased REM density was the main risk factor of RBD.

Dreaming and Insomnia: Link between Physiological REM Parameters and Mentation Characteristics.

(1) Background: An unresolved phenomenon of insomnia disorder is a discrepancy between objectively measured sleep and subjective complaints. It has been shown that rapid eye movement (REM) sleep might be especially vulnerable to an altered perception. The present work aimed to investigate the link between physiological REM parameters and mentation characteristics in REM sleep. (2) Methods: 22 patients with insomnia and 23 good sleepers indicating at least one REM mentation within an awakening study were included. Multivariate analyses of variance (MANOVAs) were calculated to examine group differences and effects of mentation characteristics on number of arousals, REM density, and spectral power prior to awakenings. (3) Results: Increased perceived wakefulness was related to lower delta, theta, and alpha power in the minute prior to the REM awakenings. Nevertheless, no group differences regarding spectral power were found. With respect to number of arousals and REM density, no significant effects of mentation characteristics and no group differences were found. (4) Conclusions: Our results suggest that spectral power in REM sleep is linked with altered sleep perception. Reduced delta, theta, and alpha power might be a signature of this modified REM sleep associated with a high level of perceived wakefulness. Future awakening studies are necessary to further explore the link between physiological REM parameters and sleep perception.

0788 Increased Rapid Eye Movement Density in Chinese Patients with Parkinson’s Disease and RBD

Abstract Introduction Impaired rapid eye movement sleep is common among patients with Parkinson’s disease (PD). However, information on rapid eye movement density (REM density) among PD patients is currently lacking. The current study sought to characterize REM density in PD patients and to examine the associations between REM density sleep parameters and clinical manifestations. Methods We retrospectively recruited 172 PD patients. All participants were assessed with a two-night polysomnography, and REM density was calculated. Clinical assessments were completed in PD patients before polysomnography. Results Rapid eye movement sleep behavior disorder (RBD) were observed in 93 patients (54.1%). The disease duration, UPDRS part III score, Hoehn and Yahr (H-Y) stage, and HAMA, HAMD, and PDQ-39 scores in the Parkinson’s disease patients with rapid eye movement sleep behavior disorder (RBD) were significantly higher than in the patients without RBD (P&amp;lt;0.05). The REM density was also significantly higher in the RBD patients than in the patients without RBD (P&amp;lt;0.05). NREM sleep stage 3 time (N3 time) and percentage of N3 time of total sleep time (N3%) were higher in patients without RBD. The forward binary logistic regression model showed that REM density, UPDRS-III score and N3 sleep time were associated with RBD in the PD patients. Conclusion Our results confirm the high prevalence of RBD in patients with PD. Increased REM density was the main risk factor of RBD. Support Special Funds of the Jiangsu Provincial Key Research and Development Projects (grant No. BE2018610)

1081 Associations Among REM Density And Parasympathetic Activity, Nightmares, And Hyperarousal In Trauma-exposed Individuals

Abstract Introduction Individuals with posttraumatic stress disorder (PTSD) exhibit autonomic hyperarousal and nightmares. We hypothesized that REM density (REMD) and REM heart rate variability would predict self-reported hyperarousal, nightmares, and PTSD diagnosis in trauma-exposed individuals. Methods Ninety-nine individuals (aged 18-40, 68 females) exposed to a DSM-5 PTSD criterion-A trauma within the past two years (48 meeting PTSD criteria) completed a night of ambulatory polysomnography (PSG) preceded by an acclimation night. REMD in scored sleep recordings were computed using the Matlab program written by Benjamin Yetton. Indices of parasympathetic tone during REM were computed using Kubios software and included Average Root Mean Square of the Successive Differences (RMSSD) and High Frequency power (HFpower). Participants completed two weeks of sleep diaries with nightmare questionnaire and completed the Clinician-Administered PTSD Scale (CAPS-5) and the PTSD Checklist for DSM-5 (PCL-5). Hyperarousal-item scores were computed from the PCL-5 without the sleep item (PCLhyp) and from the CAPS-5 (CAPShyp), and these scores (with their sleep items) were combined into a Composite Hyperarousal Index (CHI). Nightmare rate was the proportion of sleep diaries reporting a nightmare. Simple regressions measured associations among REMD, REM parasympathetic indices, hyperarousal measures, and nightmare rate. Results REMD did not significantly predict PTSD diagnosis or hyperarousal scores but did predict decreased parasympathetic activity for both RMSSD (p= 0.002, R= -0.316) and HFpower (p= 0.016 R= -0.250). REMD predicted increased nightmare rate (p= 0.011 R= 0.262). Parasympathetic tone was negatively correlated with CAPShyp, PCLhyp, and CHI for both RMSSD (p= 0.04, 0.011, &amp;lt;0.000, respectively) and HFpower (p= 0.051, 0.021, 0.010, respectively). Lower parasympathetic tone also predicted PTSD diagnosis with both RMSSD (p=0.012, t=2.559) and HFpower (p=0.010, t=2.627), but did not predict nightmare rate. Conclusion REMD predicted decreased parasympathetic tone and higher nightmare rate. Parasympathetic tone, but not REMD, predicted hyperarousal and PTSD diagnosis. Support R01MH109638

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.

Sleep, insomnia, and depression.

Since ancient times it is known that melancholia and sleep disturbances co-occur. The introduction of polysomnography into psychiatric research confirmed a disturbance of sleep continuity in patients with depression, revealing not only a decrease in Slow Wave Sleep, but also a disinhibition of REM (rapid eye movement) sleep, demonstrated as a shortening of REM latency, an increase of REM density, as well as total REM sleep time. Initial hopes that these abnormalities of REM sleep may serve as differential-diagnostic markers for subtypes of depression were not fulfilled. Almost all antidepressant agents suppress REM sleep and a time-and-dose-response relationship between total REM sleep suppression and therapeutic response to treatment seemed apparent. The so-called Cholinergic REM Induction Test revealed that REM sleep abnormalities can be mimicked by administration of cholinomimetic agents. Another important research avenue is the study of chrono-medical timing of sleep deprivation and light exposure for their positive effects on mood in depression. Present day research takes the view on insomnia, i.e., prolonged sleep latency, problems to maintain sleep, and early morning awakening, as a transdiagnostic symptom for many mental disorders, being most closely related to depression. Studying insomnia from different angles as a transdiagnostic phenotype has opened many new perspectives for research into mechanisms but also for clinical practice. Thus, the question is: can the early and adequate treatment of insomnia prevent depression? This article will link current understanding about sleep regulatory mechanisms with knowledge about changes in physiology due to depression. The review aims to draw the attention to current and future strategies in research and clinical practice to the benefits of sleep and depression therapeutics.

Nightmares do result in psychophysiological arousal: A multimeasure ambulatory assessment study.

Individuals who frequently experience nightmares report compromised sleep quality, poor daytime mood, and functioning. Previous research has aimed at linking these impairments with altered sleep architecture, but results were inconclusive. One plausible explanation is that only a few studies recorded markers of autonomic nervous system activity. For the first time, this study collected such markers under ecologically valid conditions with ambulatory assessment. In 19 individuals with frequent nightmares (≥1 nightmare/week) and 19 healthy control participants (<1 nightmare/month), measures indicating autonomic activation (heart rate, heart rate variability, respiration cycle length, electrodermal fluctuations, EEG arousals, saliva cortisol, REM density) were collected while applying ambulatory polysomnographic assessment during 3 consecutive nights. When nightmare participants reported a nightmare, we analyzed the last 5min of REM sleep before awakening and compared these data to their non-nightmares as well as to the dream episodes of control participants. Overall, there were no general differences in autonomic activation of nightmare sufferers compared to control participants. However, when nightmare participants experienced nightmares, autonomic activation was markedly increased compared to their own non-nightmares and, to some extent, to control participant's dreams. Significant intraindividual differences were found for all autonomic measures except in participant's EEG arousals and cortisol levels. Group differences were found in EEG arousals and heart rate. In conclusion, ambulatory polysomnography demonstrates that nightmares are accompanied by increased autonomic activation. Results support the notion of impaired self-reported sleep quality caused by one's autonomic response rather than altered sleep pattern.

Sleep alterations in pediatric bipolar disorder versus attention deficit disorder

Bipolar disorder (BD) and attention deficit/hyperactivity disorder (ADHD) share numerous clinical features, which can make the differential diagnosis challenging. Studies conducted in adults suggest that patients with BD and ADHD have different sleep patterns. However, in pediatric populations, data on these potential differences are scant. The present preliminary study was conducted to identify potential differences in sleep alterations among youths diagnosed with BD or ADHD compared to healthy controls (HC). A total of 26 patients diagnosed with BD (n = 13) or ADHD (n = 13) were compared to 26 sex- and age-matched HC ([HCBD], n = 13, and [HCADHD], n = 13). All participants underwent polysomnography. The mean duration of stage N2 sleep was shorter in the BD group than in controls (HCBD). The BD group also had higher (non-significant) REM density (REMd) scores than controls while mean REMd scores were lower in the ADHD group versus controls. Compared to the ADHD group, the BD group presented a shorter N2 stage, a longer first REM sleep duration (R1), and greater REMd. According to our findings, these three variables—N2 stage, REMd, and R1—appear to differentiate patients with BD from those with ADHD and from HC.

Depression and Sleep

Impaired sleep is both a risk factor and a symptom of depression. Objective sleep is assessed using the sleep electroencephalogram (EEG). Characteristic sleep-EEG changes in patients with depression include disinhibition of rapid eye movement (REM) sleep, changes of sleep continuity, and impaired non-REM sleep. Most antidepressants suppress REM sleep both in healthy volunteers and depressed patients. Various sleep-EEG variables may be suitable as biomarkers for diagnosis, prognosis, and prediction of therapy response in depression. In family studies of depression, enhanced REM density, a measure for frequency of rapid eye movements, is characteristic for an endophenotype. Cordance is an EEG measure distinctly correlated with regional brain perfusion. Prefrontal theta cordance, derived from REM sleep, appears to be a biomarker of antidepressant treatment response. Some predictive sleep-EEG markers of depression appear to be related to hypothalamo-pituitary-adrenocortical system activity.