In France, according to figures from Public Health France, 17 million people suffer from high blood pressure (HT) and 6 million are unaware of their illness. However, high blood pressure is one of the main causes of cardiovascular (myocardial infarction, stroke), renal (kidney failure) or cognitive (dementia, etc.) complications. Hence the importance of detecting it early.
Nocturnal high blood pressure: what are we talking about?
The most common chronic disease in the world, high blood pressure corresponds to excessive pressure in the arteries. “Blood pressure should be less than 140mmHg (millimeters of mercury) for systolic pressure and 90mmHg for diastolic pressureimmediately specifies Professor Gérard Helft. Beyond that, we’re talking about high blood pressure.” Our blood pressure varies throughout the day: it is highest in the morning and can increase in stressful situations… especially during a doctor’s visit! “It’s the ‘white coat’ effect”, confirms the specialist. And added: “Normally, blood pressure is significantly lower at night: it is not supposed to exceed 120/70. Nocturnal hypertension is generally a reflection of daytime hypertension. In most cases, patients who have normal daytime blood pressure do not have elevated nighttime blood pressure. On the other hand, the absence of a drop in blood pressure at night in hypertensives is more strongly correlated with cardiovascular events.
According to the Alzheimer’s Foundation, the risk of Alzheimer’s disease and related diseases is also increased in older individuals with nocturnal high blood pressure.
What are the signs of hypertension?
High blood pressure is most often asymptomatic unless the numbers are very high. It happens that it is associated with fairly non-specific signs such as:
How to diagnose it?
An asymptomatic disease, high blood pressure is often discovered incidentally during a clinical examination by the general practitioner. “The important thing is to make the diagnosis from a series of measurements and not from a single numberrecalls Professor Helft. In case of blood pressure above 140/90, the patient will be asked to take self-measurements at home using a blood pressure monitor. Compared to measuring blood pressure taken in the office, that taken at home is more reliable and has the advantage of including several measurements which will be averaged.”
According to some studies[1]one in four people with normal daytime blood pressure could suffer from nocturnal hypertension. “Nocturnal hypertension is difficult to measure since it is falsely increased when waking upspecifies the cardiologist. If necessary, it can be assessed using a 24-hour ambulatory blood pressure measurement (ABPM).
What are the causes of nocturnal hypertension?
The main known causes of no drop in blood pressure at night are:
How to treat nocturnal high blood pressure?
If high blood pressure is often rightly described as a “silent killer”, many treatments exist to remedy it. “Initially, the patient will be advised to adopt health and diet measures: weight loss in the event of overweight, reduction of salt consumption, stopping smoking, practicing regular physical activity…”, explains the cardiologist. If these new lifestyle habits do not allow normal blood pressure values to be achieved after three months, the general practitioner will prescribe antihypertensive treatment.
In the case of nocturnal high blood pressure, it is important to treat the cause: for example obstructive apnea syndrome (OSAS) or sleep disorders which can prevent a drop in blood pressure during the night. Finally, certain studies – notably the HOPE study – suggest that taking treatment (Ramipril) in the evening rather than the morning would lead to a reduction in side effects resulting from hypertension, would allow better control of nighttime blood pressure and would be associated to a better prognosis.
Sources:
[1] Sleep blood pressure self-measured at home as a novel determinant of organ damage: Japan morning surge home blood pressure (J-HOP) study. J Clin Hyperten, Kario, K., Hoshide, S., Haimoto, H., Yamagiwa, K., Uchiba, K. et al. 2015.