Chronic escitalopram treatment attenuated the accelerated rapid eye movement sleep transitions after selective rapid eye movement sleep deprivation: a model-based analysis using Markov chains

BackgroundShortened rapid eye movement (REM) sleep latency and increased REM sleep amount are presumed biological markers of depression. These sleep alterations are also observable in several animal models of depression as well as during the rebound sleep after selective REM sleep deprivation (RD). Furthermore, REM sleep fragmentation is typically associated with stress procedures and anxiety. The selective serotonin reuptake inhibitor (SSRI) antidepressants reduce REM sleep time and increase REM latency after acute dosing in normal condition and even during REM rebound following RD. However, their therapeutic outcome evolves only after weeks of treatment, and the effects of chronic treatment in REM-deprived animals have not been studied yet.ResultsChronic escitalopram- (10 mg/kg/day, osmotic minipump for 24 days) or vehicle-treated rats were subjected to a 3-day-long RD on day 21 using the flower pot procedure or kept in home cage. On day 24, fronto-parietal electroencephalogram, electromyogram and motility were recorded in the first 2 h of the passive phase. The observed sleep patterns were characterized applying standard sleep metrics, by modelling the transitions between sleep phases using Markov chains and by spectral analysis.Based on Markov chain analysis, chronic escitalopram treatment attenuated the REM sleep fragmentation [accelerated transition rates between REM and non-REM (NREM) stages, decreased REM sleep residence time between two transitions] during the rebound sleep. Additionally, the antidepressant avoided the frequent awakenings during the first 30 min of recovery period. The spectral analysis showed that the SSRI prevented the RD-caused elevation in theta (5 inverted question mark9 Hz) power during slow-wave sleep. Conversely, based on the aggregate sleep metrics, escitalopram had only moderate effects and it did not significantly attenuate the REM rebound after RD.ConclusionIn conclusion, chronic SSRI treatment is capable of reducing several effects on sleep which might be the consequence of the sub-chronic stress caused by the flower pot method. These data might support the antidepressant activity of SSRIs, and may allude that investigating the rebound period following the flower pot protocol could be useful to detect antidepressant drug response. Markov analysis is a suitable method to study the sleep pattern

Risk factors for chronic insomnia following hospitalisation

Aim. This paper reports a study whose purpose was to determine whether there is an increase in the incidence of chronic insomnia following hospitalization and, if so, to identify patients at risk.Background. The consequences of difficulty sleeping in hospital have received scant attention from clinicians or researchers. Implicit in this lack of interest is the assumption that difficulty in sleeping is a transient reaction to hospitalization that will resolve on discharge, an assumption not empirically supported. It has been argued that in susceptible people this type of temporary disruption to sleep can be the catalyst for the development of chronic insomnia.Method. Established sleep and depression rating instruments were used to monitor the sleep of 57 cardiac and 29 orthopaedic patients after elective surgery (n = 86), recruited through a hospital preadmission clinic.Results. Preadmission chronic insomnia of 10% was consistent with general population prevalence estimates of 6&ndash;12%. Three months after discharge the incidence had almost doubled to 19%. Sixty-one per cent of this variance could be explained by hyperarousal, sleep hygiene issues, and dysfunctional cognitions about sleep. Depression was found to be a salient predictor but not an independent risk factor. Age, sex, and hospital-related data, such as score for difficulty sleeping in hospital, proved to be statistically insignificant.Conclusions. The results support the role of hyperarousal and dysfunctional sleep attitudes and behaviours as stronger predictors of chronic insomnia than patient demographics or environmental issues. Given that most of the patients were ambivalent about how they slept in hospital, with high satisfaction (71%) in the presence of significant disruption (63%), preadmission sleep education given to these patients prior to admission potentially contributed to the development of more realistic expectations of the quality of in-hospital sleep.<br /