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Sex differences in blood pressure responsiveness to spontaneous K-complexes during stage II sleep

K-complexes are a key marker of nonrapid eye movement sleep, specifically during stages II sleep. Recent evidence suggests the heart rate responses to a K-complexes may differ between men and women. The purpose of this study was to compare beat-to-beat blood pressure responses to K-complexes in men and women. We hypothesized that the pressor response following a spontaneous K-complex would be augmented in men compared with women. Ten men [age: 23 ± 2 yr, body mass index (BMI): 28 ± 4 kg/m ] and ten women (age: 23 ± 5 yr, BMI: 25 ± 4 kg/m ) were equipped with overnight finger plethysmography and standard 10-lead polysomnography. Hemodynamic responses to a spontaneous K-complex during stable stage II sleep were quantified for 10 consecutive cardiac cycles, and measurements included systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and heart rate. K-complex elicited greater pressor responses in men when blood pressures were expressed as SAP (cardiac cycle sex: P = 0.007) and DAP (cardiac cycle sex: P = 0.004). Heart rate trended to be different between men and women (cardiac cycle sex: P = 0.078). These findings suggest a divergent pressor response between men and women following a spontaneous K-complex during normal stage II sleep. These findings could contribute to sex-specific differences in cardiovascular risk that exist between men and women. NEW & NOTEWORTHY K-complexes during stage II sleep have been shown to elicit acute increases in blood pressure and heart rate, but the role of sex (i.e., male vs. female) in this response is unclear. In the present study, we demonstrate that the pressor response following spontaneous K-complexes were augmented in men compared to age-matched women. The augmented blood pressure reactivity to spontaneous K-complexes during stage II sleep in men advance the field of cardiovascular sex differences, with implications for nocturnal blood pressure control

Internet Interaction Pinged and Mapped

We ping approximately 4,500 domains, 1,428 of them in Europe, six times daily, seven days a week. This paper gives an overview of both the techniques of data collection and interpretation of this data with regard to network latencies to selected domains in Europe. It includes a geographic representation of the data that gives new insight into IP networks as they are actually used in real time across time zones, providers, and national boundaries. The heart of the paper is the accompanying maps, which show usage patterns on the Internet in Europe as they cross the continent from east to west. I . Introduction Geographical plotting of latency data obtained by use of ping (ICMP ECHO) permits a perspective view of the relative distance of selected major domains in Europe according to one of the metrics that matter most on the Internet: round trip time. II . The Maps The maps included with this paper show round trip times from our hosts (tic.com) to selected hosts in Europe. They use ave..

0223 Total sleep deprivation and pain perception during cold noxious stimuli in older adults

Introduction Our laboratory has previously reported an augmented pain response to 24-hour total sleep deprivation (TSD) in young men and women. Because aging is associated with a greater prevalence of chronic pain and diminished sleep quality, we hypothesized TSD would increase pain perception to the cold pressor test (CPT) in older adults. Furthermore, we hypothesized this relationship would be stronger in postmenopausal women compared to age-matched men. Methods Eighteen participants (9 women) between 55 and 75 years were tested once after 24-hour TSD and once after normal sleep (NS) using a randomized, cross-over design. Following a supine baseline, subjects performed a 2-min CPT by immersing their left hand in water (0-3ºC). Perceived pain was recorded every 15 seconds during simultaneous recordings of muscle sympathetic nerve activity (MSNA; microneurography). Results Age (61±2 vs. 60±1 years) and BMI (26±1 vs. 27±1 kg/m2) were not different between women and men, respectively. CPT elicited a graded increase of perceived pain (time, p0.05). The condition effect was also observed when pain was expressed as mean change from baseline (NS, Δ6.9 ± 2.4 vs. TSD, Δ8.2 ± 2.4 a.u.; p=0.041) and peak change from baseline (NS, Δ8.4 ± 2.7 vs. TSD, Δ9.7 ± 2.5 a.u.; p=0.039). Changes in pain were correlated with changes in MSNA during the initial 30 seconds of CPT during both NS (r=0.513; p =0.025) and TSD (r=0.528; p=0.020). Conclusion TSD significantly augments perceived pain during cold noxious stimuli in older adults. Contrary to our initial hypothesis, this increased pain perception is not significantly different between men and women. Sympathetic reactivity during the initial phase of CPT was associated with changes in pain, but the clinical relevance of this relationship remains unclear. Our findings support the concept of sleep as a cost effective, therapeutic strategy for reducing pain in older men and women

0069 Spectral analyses of slow wave sleep and rapid eye movement sleep are associated with changes in continuous nocturnal blood pressure

Introduction Slow wave (SWS) and rapid eye movement (REM) sleep are both associated with dynamic changes in nocturnal blood pressure (BP). Specifically, SWS is often associated with the greatest reductions of nocturnal BP, while episodic increases of BP are a hallmark of REM sleep. While it is widely assumed that the respective intensities of SWS and REM impact nocturnal BP, definitive studies examining these intensities via spectral analysis during continuously recorded BP are lacking. Moreover, while increases of alpha frequencies (i.e., alpha intrusion) during REM are reported in some pathological conditions, the relation between alpha intrusion and REM BP is unknown. Methods Thirteen participants (6 female, 22±1 years, 28±1 kg/m2) were equipped with overnight finger plethysmography (NOVA, Finapres) and standard 10-lead polysomnography. Central and occipital leads were analyzed using a short-term Fourier transform function to quantify 1) delta density using delta frequencies (0.5-4 Hz) in the first and second SWS cycles and 2) alpha intrusion using alpha frequencies (8-12 Hz) in the final REM episode. Continuous systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and heart rate (HR) were recorded during wake and sleep. Results BP was significantly reduced during the first (SAP, 114±4 to 99±4 mmHg; DAP, 68±3 to 57±3 mmHg; p0.05), cycle of SWS when compared to wake. Changes in delta density across the SWS stages were significantly correlated with changes in SAP (r =-0.69, p=0.03) and DAP (r=-0.71, p=0.02). During REM, acute episodes of alpha intrusion were associated with increases of SAP (119±5 mmHg to 123±5 mmHg; p=0.039) and DAP (69±5 mmHg to 72±5 mmHg; p=0.043), but not HR. Conclusion Our findings suggest that the intensity of SWS is associated with greater reductions in nocturnal BP, and that episodes of alpha intrusion increase REM BP. These findings support growing evidence that both SWS and REM are important to cardiovascular health