Interest in the pathophysiology, measurement, and clinical implications of nocturnal blood pressure (BP) has significantly increased due to its strong association with cardiovascular risk, and its importance was recognized by the 2023 European Society of Hypertension (ESH) guidelines. Nocturnal BP regulation is complex and multifactorial, involving sleep-wake cycle, circadian rhythms, autonomic nervous system, renin-angiotensin-aldosterone system, and renal mechanisms. 24-h ambulatory blood pressure monitoring is currently the reference method for nocturnal BP assessment. Home BP monitoring, with specially designed, validated devices with nocturnal BP measuring function, may also be used, while new cuffless and wearable technologies hold great potential but require further validation. Nocturnal BP phenotypes of clinical interest include nocturnal hypertension, increased nocturnal BP variability and altered day-night BP fluctuations. Among those, isolated nocturnal hypertension may be considered a type of masked hypertension. BP variability has prognostic relevance, as do the day-night BP changes, i.e. the nocturnal BP “dipping”. Nocturnal hypertension and nondipping are particularly prevalent in individuals with autonomic neuropathies, sleep disorders (e.g., obstructive sleep apnoea), kidney disease, and metabolic or endocrine disorders, and are linked to hypertension mediated organ damage and cardiovascular risk. Therapeutic strategies targeting nocturnal BP remain debated. Chronotherapy (evening dosing of antihypertensives) has shown inconsistent results in clinical trials. Renal denervation and treatment of sleep-related breathing disorders may lower nocturnal BP and improve sleep quality. More research is needed to further clarify pathophysiology, measurement, therapeutic interventions, and overall management of nocturnal hypertension, issues on which this ESH position paper offers an in-depth review.