Naima Covassin

Sleep onset and cardiovascular activity in primary insomnia

The transition from wakefulness to sleep is characterized typically by a shift from sympathetic to parasympathetic regulation. Physiological functions, depending on the neurovegetative system, decrease overall. Previous studies have shown cardiovascular and electroencephalographic hyperactivity during wakefulness and sleep in insomniacs compared with normal sleepers, but there is very little evidence of this in the process of sleep onset. The purpose of this study was to compare cardiovascular and autonomic responses before and after falling asleep in eight insomniacs (who met DSM‐IV criteria for primary insomnia) and eight normal sleepers. Non‐invasive measures of heart rate (HR), stroke volume (SV), cardiac output (CO) and pre‐ejection period (PEP) were collected by impedance cardiography during a night of polysomnographic recording. Frequency domain measures [low‐frequency (LF), high‐frequency (HF)] of heart rate variability (HRV) were also estimated. Decrements in HR and CO and increases in SV and HF normalized units (n.u.) were found in both groups after sleep onset compared with wakefulness. Conversely, PEP (related inversely to sympathetic β‐adrenergic activity) showed increases after sleep onset in controls, but remained unchanged in insomniacs. PEP was also significantly lower in insomniacs than in normal sleepers in both conditions. These data suggest that, whereas normal sleepers follow the expected progressive autonomic drop, constant sympathetic hyperactivation is detected in insomniacs. These results support the aetiological hypothesis of physiological hyperarousal underlying primary insomnia.

Nighttime cardiac sympathetic hyper-activation in young primary insomniacs

PurposeA growing literature supports the association between insomnia and cardiovascular risk. Since only few studies have provided empirical evidence of hyper-activation of the cardiovascular system in insomniacs, the aim of the present study was to analyze cardiac autonomic responses in primary insomnia.MethodsImpedance cardiography and heart rate variability (HRV) measures were assessed in 9 insomniacs and 9 good sleepers during a night of polysomnographic recording.ResultsInsomniacs were found to be characterized by a constant sympathetic hyper-activation which was maintained all night, as suggested by a faster pre-ejection period (PEP) compared to good sleepers. In addition, only insomniacs showed a strong reduction in heart rate in the transition from wake to sleep. Both groups exhibited a reduction in cardiac output and sympathovagal balance, i.e., reductions in low-frequency/high-frequency ratio and increases in high-frequency normalized units of HRV, across the night. In addition, in our sample, a high physiological sympathetic activation (fast PEP) at night was found to be directly associated with low quality of sleep.ConclusionsThese preliminary findings suggest that a constant cardiac sympathetic hyper-activation throughout the night is a main feature of primary insomnia. Our evidences support the association between insomnia and increased risk for cardiovascular diseases.

Clinical correlates of periodic limb movements in sleep in Parkinson's disease

OBJECTIVE The aim of the current study was to investigate the frequency of periodic limb movements in sleep (PLMS) in Parkinsons disease (PD) and their impact on nocturnal sleep and daytime functioning. METHODS Forty-five PD patients (mean age 68.5 ± 8.7 years; 32 males) underwent one night of polysomnography (PSG). Clinical assessment and questionnaires evaluating sleep disturbance and quality of life (QoL) were completed. Patients were divided into two groups based on their PLMS index (PLMSI): PLMSI ≥ 15 (PLMS+) and PLMSI <15 (PLMS-). RESULTS There were 26 (57.8%) PD patients in the PLMS+group and 19 (42.2%) patients in the PLMS-group. Subjective assessment revealed an association between PLMS+status and greater PD symptom severity, more subjective sleep disturbance, and decreased QoL. All patients showed poor sleep, and no significant group differences were detected on PSG measures. CONCLUSION We observed that PLMS occurred frequently in PD and increased with more severe PD. Although PLMS did not affect objective sleep, it was associated with increased sleep complaints and reduced QoL. Overall, our findings support the association between PLMS and PD as well as the clinical relevance of sleep disturbances in PD.

Cognitive performance and cardiovascular markers of hyperarousal in primary insomnia

The purpose of the present study was to assess differences in cardiovascular activity and cognitive performance between insomniacs and good sleepers. Sixteen undergraduates participated in the study, eight insomniacs (age 22.9 ± 2.4) enrolled in accord with DSM-IV criteria for primary insomnia, and eight good sleepers (24.8 ± 2.7) were controls. The task employed, Stop Signal Task, assesses motor inhibition processes and was administered in two sessions, before and after a night of polysomnographic recording. During task performance, cardiovascular measures such as heart rate (HR), stroke volume (SV), cardiac output (CO), pre-ejection period (PEP) and left ventricular ejection time (LVET) were continuously recorded by means of impedance cardiography. 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. Analyses performed on cardiovascular parameters revealed higher HR and lower LVET values in the insomnia group as compared to healthy controls in the evening. PEP, an index inversely related to sympathetic beta-adrenergic activity, was continuously reduced in insomniacs, indicating constantly enhanced sympathetic activation. These findings suggest a deficit of motor inhibition control in insomnia, matched with high levels of cardiovascular arousal. Overall, our results support the notion that insomniacs suffer from both cognitive deficits and a hyperarousal disorder affecting somatic activity, that contribute to diurnal complaints often referred in addition to sleep disruption.

Hemodynamic and autonomic modifications during sleep stages in young hypotensive women

This study examined cardiovascular activity and autonomic involvement during sleep in essential hypotension. We compared young female hypotensives and normotensives using ambulatory blood pressure monitoring, impedance cardiography, and frequency-domain analysis of heart rate variability during a night of polysomnographic recording. Hypotensives, as compared to normotensives, exhibited lower blood pressure, reduced myocardial contractility and reduced sympathovagal balance across the whole night. Both groups exhibited a reduction in cardiovascular involvement from wake to sleep with similar cardiovascular activity during wake and REM. No group difference was observed in sleep architecture suggesting similar sleeping quality in hypotensives and normotensives. The lower blood pressure and reduced myocardial contractility associated with a lower sympathovagal balance in hypotensives, as compared to normotensives, suggest a night-time hypoactivation of the cardiovascular system supporting the hypothesis of impairment in autonomic control in essential hypotension.

Cardiovascular down‐regulation in essential hypotension: Relationships with autonomic control and sleep

In this work, we aimed to clarify the autonomic involvement in the cardiovascular down-regulation in essential hypotension. The relationships between cardiovascular response and sleep quality were also examined. Thirteen female hypotensives and 13 female normotensives performed a stress task followed by polysomnography. Measures derived from blood pressure monitoring, impedance cardiography, and heart rate variability were collected. Hypotensives exhibited lower cardiovascular and autonomic activation than controls during the task. While a better sleep quality (i.e., higher sleep efficiency and lower nocturnal wakefulness) correlated with a reduced reactivity in normotensives, the opposite pattern occurred in hypotensives. The results suggest that a blunted response in both autonomic branches underlies the cardiovascular hypoactivation in hypotension. Further, good sleep seems to be associated with optimal levels of physiological reactivity.

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.

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 hypotensives was associated to a poorer task performance. Essential hypotension was 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.

Nocturnal cardiovascular activity in essential hypotension: evidence of differential autonomic regulation.

Objective Essential hypotension represents a form of chronic low blood pressure (BP) not explained by medical or orthostatic conditions. The pathogenesis of essential hypotension may involve sympathetic hypoactivation and other forms of autonomic dysregulation. The aim of the current study was to investigate autonomic and cardiovascular activity during sleep in individuals with essential hypotension. Methods A case-control study was conducted in 14 individuals with essential hypotension (mean [standard error] = 23.4 [0.6] years, all women) and 14 controls (mean [standard error] age = 22.2 [0.4] years, all women). The following measures were collected over a night of sleep: BP, heart rate (HR), stroke volume, cardiac output (CO), preejection period (PEP), total peripheral resistance, and time-domain measures of HR variability. Results Hypotensive participants had consistently lower BP, HR, and CO than did normotensives. Cardiac autonomic variables revealed enhanced parasympathetic tone (proportion of adjacent normal-to-normal intervals that differed in length by more than 50 milliseconds = 40.8 [6.3] versus 23.4 [4.5], p = .03) and reduced sympathetic drive in hypotensives (PEP = 99.4 [3.6] versus 86.1 [4.3], p = .02). Analysis of temporal profiles showed that HR, stroke volume, and CO decreased throughout the night in both groups, whereas PEP and HR variability increased. Unlike controls, BP remained essentially unchanged in hypotensives, as the decrease in CO was counterbalanced by a parallel rise in total peripheral resistance. Conclusions These findings suggest that nocturnal cardiac sympathetic withdrawal combined with vagal hyperactivity is a characteristic of the autonomic regulation in essential hypotension.

Relationship between cardiovascular resting state and visual attention

IntroductionCardiovascular features seem to modulate performance in attention tasks.MethodsWe investigated the relationship between blood pressure, resting heart rate and heart rate variability (HRV) and performance in a visuospatial attention task comparing normotensive and hypotensive young adults.ConclusionsWe found an association between resting HRV and visual attention performance only in the normotensive group. In addition, we provided a further evidence of attention impairment in hypotensive individuals.