BACKGROUND: Circadian blood pressure (BP) abnormalities, including nondipping and reverse-dipping patterns, are increasingly recognized as major determinants of cardiovascular target-organ damage, independent of clinic BP. Antihypertensive drug classes and dosing time may differentially influence nocturnal BP control and left ventricular (LV) remodeling. However, real-world data integrating these factors remain limited, particularly in Chinesepopulations. METHODS: This retrospective, observational study included 500 adult patients with essential hypertension evaluated at a tertiary-care center between 2020 and 2024. All patients underwent valid 24-hour ambulatory BP monitoring (ABPM) and transthoracic echocardiography performed within six months of ABPM. Antihypertensive therapy was classified by drug class and dosing time (morning-only vs. evening/bedtime dosing of ≥ 1 agent). Circadian BP phenotypes were defined based on nocturnal systolic BP decline. LV mass index (LVMI) and LV geometric patterns were assessed according to standard echocardiographic criteria. Multivariable regression analyses were performed to evaluate associations between antihypertensive regimen, circadian BP indices, and LV remodeling. RESULTS: Nondipping or reverse-dipping BP patterns were present in 48.6% of patients. RAAS-blocker-based regimens and bedtime dosing were associated with significantly lower nighttime BP, greater nocturnal BP decline, reduced morning BP surge, and a higher prevalence of preserved dipping compared with non-RAAS regimens and morning-only dosing (all p < 0.01). LV hypertrophy (LVH) was observed in 27.2% of patients and was significantly more prevalent among nondippers and reverse dippers. LVMI and relative wall thickness increased progressively with worsening circadian BP phenotype (p < 0.001). In multivariable models, nondipping (OR 1.89) and reverse dipping (OR 2.64), higher nighttime systolic BP, and nocturnal hypertension were independently associated with LVH. RAAS-based therapy and bedtime dosing were associated with lower odds of LVH, with partial attenuation after adjustment for nocturnal BP indices. CONCLUSIONS: In treated hypertension, circadian BP abnormalities remain common and are strongly associated with adverse LV remodeling. Antihypertensive drug class and dosing time are important determinants of nocturnal BP control and cardiac structural changes, highlighting the clinical value of ABPM-guided, individualized treatment strategies.