title: Circadian mechanisms of 24-hour blood pressure regulation and patterning.
abstract: In most persons, blood pressure (BP) rises slowly during late sleep, increases rapidly upon morning awakening and commencement of diurnal activity, exhibits two - morning and afternoon/early evening - daytime peaks, shows a minor midday nadir, and undergoes a decline during nighttime sleep by 10-20% in systolic BP and somewhat lesser amount in diastolic BP relative to wake-time means. Nyctohemeral cycles of ambient temperature, light, noise and behaviorally driven temporal patterns in food, liquid, salt, and stimulant consumption, mental/emotional stress, posture, and physical activity intensity plus circadian rhythms of wake/sleep, pineal gland melatonin synthesis, autonomic and central nervous, hypothalamic-pituitary-adrenal, hypothalamic-pituitary-thyroid, renin-angiotensin-aldosterone, renal hemodynamic, endothelial, vasoactive peptide, and opioid systems constitute the key regulators and determinants of the BP 24 h profile. Environmental and behavioral cycles are believed to be far more influential than circadian ones. However, the facts that the: i) BP 24 h pattern of secondary hypertension, e.g., diabetes and renal disease, is characterized by absence of BP fall during sleep, and ii) scheduling of conventional long-acting medications at bedtime, rather than morning, results in much better hypertension control and vascular risk reduction, presumably because highest drug concentration coincides closely with the peak of most key circadian determinants of the BP 24 h profile, indicate endogenous rhythmic influences are of greater importance than previously appreciated.
authors.affiliation: Department of Biomedical Engineering, Cockrell School of Engineering, The University of Texas at Austin, 107 W. Dean Keaton St., Austin, TX 78712-0238, USA. Electronic address: Michael.H.Smolensky@uth.tmc.edu.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Smolensky
authors.affiliation: Bioengineering & Chronobiology Laboratories, Atlantic Research Center for Information and Communication Technologies (AtlantTIC), University of Vigo, Vigo, Spain.
authors.forename: Ramón C
authors.initials: RC
authors.lastname: Hermida
authors.affiliation: Hypertension Center, S. Anna University Hospital, University of Ferrara, Ferrara, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Portaluppi
mesh_terms: D000959:Antihypertensive Agents / Q000627:therapeutic use; D001341:Autonomic Nervous System / Q000502:physiology*; D001794:Blood Pressure; D018660:Blood Pressure Monitoring, Ambulatory; D002940:Circadian Rhythm / Q000502:physiology*; D006801:Humans; D006973:Hypertension / Q000503:physiopathology; D012084:Renin-Angiotensin System / Q000502:physiology; D012890:Sleep / Q000502:physiology*; D013997:Time Factors
chemical_list: D000959:Antihypertensive Agents
keywords: Autonomic nervous system; Bedtime hypertension chronotherapy; Blood pressure; Circadian rhythm; Endothelial factors; Melatonin; Renal hemodynamics; Renin-angiotensin-aldosterone system; Sleep/wake cycle; Vasoactive peptides