Funding: supported by the grant of the Russian Science Foundation ‘Analysis of altered circadian expression of cytokines in blood of patients with essential hypertension as predictor of cardiovascular complications’, № 23-25-00147.

Author contribution: Radaeva OA — trial design, analysis of results, preparation of a manuscript; Simbirtsev AS — stating the purpose of the trial, editing; Kostina YuA — lab research, preparation of a manuscript; Iskandyarova MS — working with literature, editing; Negodnova EV — working with literature, surveillance over patients; Mashnina SV, Krasnoglazova KA, Babushkin IO — statistical treatment of data; Eremeev VV — editing.

Compliance with ethical standards: The trial was approved by the Ethics Committee of the National Research Mordovia State University (protocol № 12 as of December 14, 2008, protocol № 85 as of May 27, 2020). All patients signed a voluntary informed consent form. Biological sample (blood) was obtained in accordance with the provisions of Declaration of Helsinki of BMA (2013), protocol of Council of Europe Convention for the Protection of Human Rights and Biomedicine (1999) and additional protocol to Convention for the Protection of Human Rights and Biomedicine in the area of biomedical research (2005).