Today, increasing attention is being paid to the role of circadian rhythms in pathology. There are time-of-day-dependent immune markers that provide valuable information about disease progression. The aim of this study was to measure evening and morning concentrations of a few cytokines (interleukins, adhesion molecules, tumor necrosis/growth factors, etc.) in the peripheral blood of patients with stage II essential hypertension and to investigate how they correlate with a nocturnal blood pressure decline. Blood samples were collected from 90 patients with stage II EH at 7:00 a.m. and 8:00 p.m. Cytokine concentrations were measured using immunoassays. Based on 24-h blood pressure monitoring, the patients were distributed into 3 groups: dippers, non-dippers and night-peakers. The morning to evening ratios of cytokine concentrations in patients with EH differed from those in healthy controls due to an increase in the evening concentrations of somnogenic cytokines (IL1β, IL1α) and LIF, sLIFr, and M-CSF whose daily fluctuations patterns remain understudied. On the whole, the fluctuation patterns of the measured cytokines in patients with stage II EH who had had the condition for 10 to 14 years and were receiving no antihypertensive treatment at the time of our study differed from those displayed by healthy controls. A twenty percent rise in the evening concentrations of IL1α, LIF, sLIFr, M-CSF, and erythropoietin contributes significantly to pathological blood pressure rhythms (as demonstrated by the groups of non-dippers and night-peakers) in patients with stage II EH receiving no antihypertensive therapy. Understanding the pathophysiological role of cytokine levels and their fluctuations over a 24-h cycle could inspire new methods for EH prevention and reduce end-organ damage.