Abstract Isolated nocturnal hypertension (INH) is a special type of out‐of‐office hypertension. Its determinants and pathophysiology remain unclear. In a nested case‐control study, we intend to investigate the host, environmental, and genetic factors in relation to INH. Among 2030 outpatients screened from December 2008 till June 2015, 128 patients with INH were identified, and then 128 normotensives were matched according to sex and age. INH was an elevated nocturnal blood pressure (BP ≥120/70 mmHg) in the presence of a normal daytime BP (