Introduction: Obstructive sleep apnea (OSA) has been associated with non-dipping blood pressure (BP). The precise mechanism is still under investigation, but repetitive oxygen desaturation and arousal induced sleep fragmentation are considered the main contributors. Methods:We analyzed beat-to-beat measurements of hemodynamic parameters (HPs) during a 25-min period of wake-sleep transition. Differences in the mean HP values for heart rate (HR), systolic BP (SBP), and stroke volume (SV) during wake and sleep and their standard deviations (SDs) were compared between 34 controls (C) and 22 OSA patients. The Student's t-test for independent samples and the effect size by Cohen's d (d) were calculated. HP evolution was investigated by plotting the measured HP values against each consecutive pulse wave. After a simple regression analysis, the calculated coefficient beta (SCB) was used to indicate the HP evolution. We furthermore explored by a hierarchical block regression which variables increased the prediction for the SCB: model 1 BMI and age, model 2 + apnea/hypopnea index (AHI), and model 3 + arousal index (AI).Results: Between the two groups, the SBP increased in OSA and decreased in C resulting in a significant difference (p = 0.001; d = 0.92). The SV demonstrated a similar development (p = 0.047; d = 0.56). The wake/sleep variation of the HP measured by the SD was higher in the OSA group-HR: p < 0.001; d = 1.2; SBP: p = 0.001; d = 0.94; and SV: p = 0.005; d = 0.82. The hierarchical regression analysis of the SCB demonstrated in SBP that the addition of AI to AHI resulted in R 2 : +0.163 and F + 13.257 (p = 0.001) and for SV R 2 : +0.07 and F 4.83 (p = 0.003). The AI but not the AHI remained statistically significant in the regression analysis model 3-SBP: β = 0.717, p = 0.001; SV: β = 0.469, p = 0.033. Frontiers in Physiology | www.frontiersin.org 1 March 2020 | Volume 11 | Article 104 Staats et al. Sleep Fragmentation and Hemodynamic DippingConclusion: In this study, we demonstrated that in OSA, the physiological dipping in SBP and SV decreased, and the variation of all investigated parameters increased. Hierarchical regression analysis indicates that the addition of the AI to BMI, age, and AHI increases the prediction of the HP evolution following sleep onset for both SBP and SV and may be the most important variable.

AimThe prevalence of obesity has been steadily increasing and is a major worldwide public health problem. It is associated with multiple medical and psychological conditions and recent research supports a link to several cognitive deficit domains, including executive functioning. The aim of this article is to describe socio-demographic, clinical and neuropsychological characteristics of a sample of candidates for bariatric surgery (BS) and to compare their performance with normative values.MethodBetween May 2012 and May 2013 we evaluated the neuropsychological performance of 42 patient candidates for BS at the Morbid Obesity Consultation at Centro Hospitalar Lisboa Norte (CHLN).ResultsThe population was predominantly female and education was equally distributed between basic, secondary and tertiary levels. The neuropsychological results showed a significant decrease on Recall (p < .01), Learning (p < .10), Nonverbal Memory (p < .001), Cognitive Flexibility (p < .01) and Resistance to Interference (p < .05).ConclusionDespite the limitations inherent to a small sample, the results obtained in the Portuguese population coincide with those of earlier studies; namely that obesity differentially effects instrumental functions.

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