Cardiovascular Hyperarousal and Primary Insomnia

Previous researches has shown autonomic, neuroendocrine, neuroimmunological, elecrophysiological and neuroimaging evidence of increased levels of arousal during wakefulness and sleep in primary insomnia. However, few studies have focused on cardiovascular activity across sleep stages and there are even fewer that have studied cardiovascular activity during the process of falling asleep. The aim of the present study is to analyze cardiovascular activity during sleep in primary insomniacs compared to good sleepers. We also aim to detect differences in cardiovascular activity and cognitive performance between insomniacs and good sleepers. This will be done by employing Impedance Cardiography and heart rate variability (HRV) analysis. The task employed, Stop Signal Task, assesses motor inhibition processes and was administered in two sessions, before and after a night of polysomnographic recording. Performance results showed prolonged Stop Signal Delay (SSD) in the morning in both groups and slower Stop Signal Reaction Time (SSRT) in insomniacs compared with good sleepers, while no effects were observed for performance accuracy. The myocardial contractility, in insomniacs, was higher (elevated heart rate and reduced left ventricular ejection time) in the evening task session and during wake compared to sleep. Pre-ejection period, an index inversely related to sympathetic beta-adrenergic activity, was lower in insomniacs overall the night and task sessions in agreement with the hypothesized sympathetic hyperactivity underlied the disorder. In addition, HRV indexes showed an increased parasympathetic involvement (elevated high frequency) in wake, but only in insomniacs. These findings suggest that, in insomniacs, a greater parasympathetic activation is required to fall asleep; possibly to contrast the sympathetic hyperactivation reflected in other variables. In addition, these findings suggest a deficit of motor inhibition control in insomnia, matched with high levels of cardiovascular arousal. These results support the etiological hypothesis of physiological hyperarousal underlying primary insomnia. Furthermore, elevated contractility indexes suggest an association between insomnia and increased risk for cardiovascular diseases.Dalla letteratura emerge come l’insonnia sia associata ad una condizione di iperattivazione generalizzata. Ciononostante solamente pochi studi si sono focalizzati sull’attività cardiovascolare nel sonno degli insonni ed in particolar modo rimane poco studiato l’addormento, ritenuto fondamentale nella comprensione del disturbo. Lo scopo dello studio è di analizzare l’attività cardiovascolare durante il sonno nell’insonnia primaria utilizzando la Cardiografia ad Impedenza e misure derivate dall’analisi della variabilità della frequenza cardiaca. Inoltre ci si propone di analizzare la prestazione cognitiva e la reattività cardiovascolare ad un compito che coinvolge l’inibizione motoria, in un gruppo di insonni confrontati con buoni dormitori. I risultati dello studio mostrano, negli insonni, un rallentamento nei tempi di risposta ai segnali di stop (SSRT), mentre l’accuratezza non sembra differire tra insonni e controlli. A livello fisiologico, gli insonni, alla sera e nel confronto tra veglia e sonno, mostravano un elevata contrattilità miocardica (maggiore frequenza cardiaca e minore tempo di eiezione ventricolare sinistra). Il periodo pre-eiettivo, un indice inversamente relato all’attività simpatica beta-adrenergica, era inferiore negli insonni in tutte le condizioni sperimentali. In aggiunta, gli indici derivati dalla variabilità della frequenza cardiaca hanno evidenziato negli insonni un incremento del coinvolgimento parasimpatico in veglia. Questi risultati suggeriscono come negli insonni sia necessaria un importante influenza vagale per permettere l’addormentamento, possibilmente per contrastare l’iperattivazione simpatica. In aggiunta, questi risultati suggeriscono un deficit nel controllo dell’inibizione motoria negli insonni che contemporaneamente esibiscono degli elevate livelli di arousal cardiovascolare durante l’esecuzione del compito. I risultati supportano l’ipotesi eziologica di una iperattivazione psicofisiologica alla base del disturbo. Inoltre, gli elevati indici di contrattilità negli insonni, suggeriscono un associazione tra insonnia e rischio cardiovascolare

Cardiac autonomic profile during rest and working memory load in essential hypotensive women

To our knowledge, no previous study has provided reliable data supporting a different modulation of the Neurovegetative system in essential hypotension. Our purpose was to provide, in essential hypotensive women compared to normotensives, evidence of a distinct sympathetic and parasympathetic cardiac control. Cardiovascular and autonomic indexes derived by impedance cardiography (heart rate, HR; pre-ejection period, PEP), photoplethysmographic technique (blood pressure, BP) and heart rate variability analysis (high and low frequencies power, HF and LF) were continuously collected during rest and mental stress condition. Hypotensives, compared to normotensives, exhibited prolonged PEP (low sympathetic tone) and elevated HF (high vagal involvement) during rest. In addition, they showed cardiovascular (reduced increases in BP and HR) and sympathetic (lower reductions of PEP) hypo-reactivity to the task. Furthermore, a lower sympathetic reactivity in hypotensiveswas associated to a poorer task performance. Essential hypotensionwas characterized by a low sympathetic and high parasympathetic tone. In addition, a reduced sympathetic nervous system reactivity suggests the main role of the Neurovegetative system in mediating the relationship between blood pressure and cognitive performance in hypotensives

Impaired cerebral and systemic hemodynamics under cognitive load in young hypotensives: a transcranial Doppler study

Reduced sympathetic outflow and deficits in cerebral hemodynamics have been considered as possible factors mediating the impaired cognitive performance in essential hypotension. However, the relationship between systemic blood pressure (BP), cerebral blood flow and cognitive functioning is still poorly understood. The present study was aimed at clarifying the physiological processes underlying cerebral and systemic hemodynamics in young hypotensives during cognitive engagement. Doppler sonography blood flow velocities in both middle cerebral arteries were measured from 17 hypotensives and 15 normotensives during a working memory task. Impedance cardiographic and BP measures were also recorded continuously. Lower increases in systolic and diastolic BP were observed in hypotensives. However, no evidence of lower sympathetic control was found for this group, as assessed by pre-ejection period. Flow velocity in middle cerebral arteries showed a lower increase in hypotensives throughout the task. Moreover, significant positive correlations between BP changes and blood flow velocities in middle cerebral arteries during the task were obtained for this group only, suggesting a less effective cerebral autoregulation. No difference was found between groups in task performance. Results suggest that during cognitive challenge hypotensives show impaired hemodynamic adjustments, both central and peripheral. However, such alterations do not directly affect cognitive performance, at least under moderate cognitive load

Impaired off-line motor skills consolidation in young primary insomniacs

Compelling evidence indicates that sleep can facilitate the off-line consolidation of declarative, perceptual, emotional and procedural memories. Here we assessed the sleep-related off-line consolidation of motor skills in 13 young primary insomniacs (23.31 +/- 2.5 yrs) compared to 13 healthy sleepers (24.31 +/- 1.6 yrs) using the sequential finger tapping task. During a training session insomniacs performed less correct sequences than controls. However, both groups exhibited similar on-line motor learning in the pre-sleep evening session. After a night of sleep, healthy controls improved their performance, indicating an overnight effect of sleep on motor skills consolidation. In contrast, insomniacs failed to exhibit a sleep-related enhancement in memory performance indicating impairment in the off-line motor skills consolidation process. Our results suggest that young adults with insomnia experience impaired off-line memory consolidation which seems not to be associated with reduced ability to acquire new motor information