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Exposure to bright morning light (BML) entrains the master circadian clock, modulates physiological circadian rhythms, and reduces sleep–wake disturbances. However, its impact on the autonomic nervous system at night remains unclear. Here, we investigated the effects of BML exposure on parasympathetic nervous system (PSNS) and sympathetic nervous system (SNS) activity at night in elderly women. This nonrandomized controlled pilot study included female participants aged ≥ 60 years who were diagnosed with a type of dementia or cognitive disorder, excluding individuals with pacemakers. The treatment group was exposed to 2500 lx of BML, whereas the control group was exposed to 200 lx of general lighting. We measured heart rate variability to quantify ANS activity. The treatment group displayed significant increases in high-frequency (HF) power (Roy's largest root = 1.62; p < 0.001) and nonsignificant decreases in normalized low-frequency (LF%) power. The corresponding nonsignificant decreases in the low-frequency/high-frequency (LF/HF) ratio and cognitive function were correlated with PSNS activity (Roy's largest root = 1.41; p < 0.001), which improved severe dementia. BML exposure reduced SNS activity and enhanced PSNS activity at night in female participants, which improved cognitive function. Thus, BML therapy may be a useful clinical tool for alleviating cognitive decline. [ABSTRACT FROM AUTHOR]

Background: Sympathetic hyperactivity and poor sleep quality have been reported in patients with myocardial infarction (MI). Sleep is an important modulator of cardiovascular function. We aimed to evaluate the effects of renal denervation (RDN) on cardiac autonomic activity and disordered sleep patterns in rats with MI.Methods: Wireless transmission of polysomnographic recordings was performed in sham and left coronary artery (LCA) ligation male rats during normal daytime sleep before and after RDN. Spectral analyses of electroencephalogram and electromyogram (EMG) recordings were performed to define active waking, quiet sleep, and paradoxical sleep. Cardiac autonomic activity was measured by analyzing the power spectrum of heart rate variability. Central sleep apnea events were measured by analyzing the EMG recordings of the diaphragm.Results: In the LCA ligation group, there was a higher low-frequency (LF)/high-frequency (HF) power ratio during sleep; the LF/HF ratio decreased significantly in the rats that underwent RDN in all sleep stages when compared with that in the rats that did not. The frequency of sleep interruptions increased without RDN in the LCA ligation group when compared with that in the sham group. This change was ameliorated and prevented with RDN in the LCA ligation group.Conclusions: Our results demonstrate significant sleep fragmentation with sympathetic hyperactivity after MI and that RDN prevents autonomic dysfunction and disordered sleep. RDN may then reduce sleep apnea and sleep-related sudden cardiac death after MI by restoring autonomic homeostasis. [ABSTRACT FROM AUTHOR]

Purpose: The frequency of breathing influences the spectral powers of heart rate variability (HRV) as well as the magnitudes of heart rate deceleration capacity (DC) and acceleration capacity (AC). We compared the strength of their relationships under different breathing frequencies.Methods: We studied 14 healthy young adults who breathed spontaneously and controlled their breathing rates to 0.1, 0.2, 0.3 and 0.4 Hz in a supine position. A 5-min R-R interval time series without movement artefacts or ectopic beats was obtained for each study period. Spectral indices were defined as the square roots of spectral powers in the very low frequency (0.01-0.04 Hz), low frequency (0.04-0.15 Hz), high frequency (0.15-0.4 Hz) and respiratory frequency bands. We also combined these frequency bands into LHF (0.04-0.4 Hz) and VLHF (0.01-0.4 Hz). DC and AC were obtained using phase rectified signal averaging.Results: DC and AC were significantly correlated with all indices of HRV. The within-subject correlation coefficients for the LHF index had the greatest absolute values (0.953 and -0.919, respectively). DC and AC had different strength of relationships with the LHF index, but became comparable (0.954 vs. -0.943) when the data obtained under 0.1-Hz breathing were excluded.Conclusion: DC is strongly correlated with the spectral index of the LHF band, indicating that they are controlled by similar influences under the conditions used in this study. AC is less related to the LHF index due to the fact that its magnitude deceases during 0.1-Hz breathing. [ABSTRACT FROM AUTHOR]

Purpose: The deceleration capacity (DC) and acceleration capacity (AC) of heart rate as well as the respiratory rate predict outcome after acute myocardial infarction. We evaluated the relation between breathing frequency and both DC and AC, as well as the difference between them.Methods: We studied fourteen healthy young adults who breathed spontaneously and controlled their breathing to rates of 0.1, 0.2, 0.3, and 0.4 Hz in a supine position. A 5-min R-R interval time series without movement artifacts or ectopic beats was obtained from each studied period and scanned to identify the anchor points that were characterized by a value longer or shorter than the preceding value. Averaged changes of R-R intervals surrounding the deceleration and acceleration anchors were calculated as DC and AC, respectively.Results: The magnitudes of DC and AC increased progressively as breathing frequency decreased (Both p < 0.001 by one-way repeated-measures analysis of variance). The magnitude of DC was larger than the magnitude of AC during 0.1-Hz breathing (95 % confidence interval of their difference: 1.7-9.7 ms), while the difference between them reduced to near zero at higher frequencies.Conclusions: Slow breathing enhances the magnitudes of DC and AC simultaneously under the conditions used in this study. The increase in the magnitude of DC is significantly greater than that of AC. [ABSTRACT FROM AUTHOR]

Many studies have reported that the production of Lactobacillus brevis is beneficial for sleep, but the underlying mechanism remains unclear. Other known beneficial effects of Lactobacillus brevis include improvement of anxious or depressive symptoms and better modulation of the autonomic nervous system, both of which impact sleep. In this study, we investigated whether the sleep benefit of Lactobacillus brevis was associated with the modulating effects on the autonomic nervous system and anxious/depressive symptoms. Wistar–Kyoto rats were fed the production of Lactobacillus brevis (ProGA28) for the last 2 weeks of treatment before being exposed to case exchange (stress-induced insomnia paradigm). Waking, quiet sleep, and paradoxical sleep states were defined based on polysomnographic measurements. Autonomic functioning was assessed by heart rate variability (HRV). A combined behavioral test was used to evaluate anxiety-like or depressive-like behaviors after the following 2 days. In exposure to the dirty cage, the control group had significant prolongation of sleep latency, sleep loss during the first 2 h, and decreased parasympathetic activity and increased sympathetic activity during quiet sleep, which were significantly mitigated in the ProGA28 group. In behavioral tests, the ProGA28 group exhibited significantly less anxiety/depression-like motor responses in the elevated plus maze test, the forced swimming test, and the three-chamber social interaction test. Less initial sleep loss in the ProGA28 group was related to higher parasympathetic activity during quiet sleep, and shorter sleep latency in both groups was associated with longer time staying in the open arm in the elevated plus maze test. These findings suggest that L. brevis ProGA28 can attenuate stress-related sleep disturbance, which may be associated with increased parasympathetic activity and decreased anxiety-like behaviors. [ABSTRACT FROM AUTHOR]

Background Sympathetic hyperactivity and poor sleep quality are reported in myocardial infarction (MI) patients and angiotensin-converting enzyme inhibitors (ACEI) can improve long-term survival in these patients. We aimed to evaluate ACEI effects on cardiac autonomic activity (CAA) and disordered sleep patterns in ambulatory rats after MI. Methods Polysomnographic recording was performed in sham (n = 8) and MI (n = 9) male rats during normal daytime sleep before and after captopril treatment. Spectral analyses of the electroencephalogram and electromyogram were evaluated to define active waking (AW), quiet sleep (QS), and paradoxical sleep (PS). Central sleep apnea (CSA) events were measured by analyzing the electromyogram of the diaphragm. CAA was measured by power spectrum analyses of heart rate variability (HRV). Results In the MI group, there was a higher low frequency/high frequency ratio during sleep, which reduced significantly after captopril treatment, especially at the QS stage compared to that before captopril treatment. The frequency of sleep interruption was higher in the MI group than the sham group. Increased AW and PS, and decreased QS times were noted in the MI group compared to the sham group. These changes were restored to baseline after captopril treatment in the MI group. CSA events were significantly increased in the MI group, and were restored to the normal level after captopril treatment. Conclusions Our results demonstrate significant sleep fragmentation with sympathetic hyperactivity after MI, and that captopril restores the autonomic dysfunction and sleep disorder. These findings suggest that ACEI improved sleep-related respiration disorder after MI by restoring autonomic homeostasis, and provide a hypothesis generating for future studies in humans. [ABSTRACT FROM AUTHOR]