Narrative review: The forgotten side of the coin-Hypotension and nocturnal blood pressure declines in ambulatory monitoring.

While hypertension remains the leading modifiable cardiovascular risk factor, the opposite end of the spectrum-hypotension, particularly during sleep-has received limited attention. This narrative review synthesizes current evidence on nocturnal hypotension as assessed by ambulatory blood pressure monitoring (ABPM), including its pathophysiological mechanisms, epidemiology, and clinical consequences. Definitions varied markedly, from absolute nocturnal blood pressure (BP) thresholds (<90/50mmHg) to relative declines (>20% from daytime BP). Excessive nocturnal BP reduction has been associated with cardiovascular events, optic neuropathies-particularly normal-tension glaucoma-cognitive decline, and increased fall risk in older adults. Antihypertensive therapy, especially intensive or bedtime dosing, may accentuate these effects in vulnerable populations. Recognition of nocturnal hypotension as a distinct and clinically relevant phenomenon underscores the value of ambulatory BP monitoring to detect excessive nocturnal declines and balance cardiovascular protection with the prevention of hypoperfusion-related damage. Standardized definitions and prospective studies are urgently needed to clarify its prognostic significance.