Hypertension is a serious medical condition that affects millions of people all over the world. The problem is particularly acute in India. According to estimates, there are over 200 million Indians who have elevated blood pressure. Thanks to increasing awareness around hypertension and the availability of monitoring equipment, it is now much easier to detect high blood pressure levels.
It is worth noting that most people get their blood pressure levels checked during daytime hours. As a result, high blood pressure levels during nighttime is often overlooked. However, the findings of a recently published Japanese study have highlighted the negative impact of nighttime high blood pressure on cardiovascular health. In order to understand the findings of the study, it is important to know more about nocturnal hypertension.
What is nocturnal hypertension?
According to the American Heart Association, nocturnal hypertension is a condition in which the average nighttime systolic and diastolic blood pressure levels are more than 120 mmHg and 70 mmHg, respectively.
Ambulatory blood pressure monitoring (ABPM) technique is used to calculate the nighttime blood pressure. In ABPM, a small digital device is used to record blood pressure (BP) levels over a 24-hour period. The average of the blood pressure levels recorded during sleep is calculated as the nighttime blood pressure.
Study on the impact of nocturnal hypertension on heart health
A study titled “Nighttime Blood Pressure Phenotype and Cardiovascular Prognosis” was published in the medical journal Circulation on November 2, 2020. The objective of the study was to investigate the association between nocturnal hypertension and nighttime blood pressure dipping patterns and the incidence of cardiovascular events, including heart failure, in hypertensive patients. The study enrolled 6772 participants in Japan, of which 6359 were included in the final analysis.
All the study participants had at least one cardiovascular risk factor, and most of them were on anti-hypertension medication. None of the participants had cardiovascular disease at the beginning of the study. During the study, the participants wore an ABPM device that recorded 20 daytime and 7 nighttime blood pressure levels.
The study revealed the following outcomes:
- A total of 306 cardiovascular events were recorded during the course of the study. The study participants experienced 88 cases of heart failure, 99 cases of coronary artery disease, and 119 cases of strokes.
- The study found that people who recorded a nighttime systolic blood pressure 20 mm Hg more than their daytime systolic reading were more likely to experience atherosclerotic cardiovascular disease and heart failure.
- Interestingly, the study also noted that the participants who controlled their blood pressure levels with medication but experienced a high reduction in blood pressure during their sleep were at a greater risk of strokes.
Factors responsible for nocturnal hypertension
Researchers believe that certain factors can increase the risk of nocturnal hypertension. These factors include:
- Old age
- Hypertension (daytime)
- Obstructive sleep apnea
- Kidney disease
- Thyroid problems
- High salt sensitivity
Behavioural factors such as high salt intake, sedentary lifestyle, tobacco use, excess consumption of alcohol, poor sleep, and night shift work can also increase the risk of nocturnal hypertension.
How to prevent nocturnal hypertension?
Preventative measures for nocturnal hypertension usually focus on addressing the risk factors contributing to nocturnal hypertension. Some of these measures include:
- Take blood pressure medication in the evening
- Get enough sleep
- Control stress and anxiety
- Reduce the intake of salt
- Quit smoking
- Avoid caffeinated beverages and alcohol later in the day
- Manage blood glucose levels
- Avoid napping during the day
- Increase physical activity (during the daytime hours)
- Avoid exposure to blue light from digital devices.
The findings of the latest research on nocturnal hypertension have highlighted the need to monitor nighttime blood pressures in both healthy and hypertensive individuals. Researchers have suggested focusing on anti-hypertensive strategies to keep nighttime blood pressure under control. By reducing blood pressure levels during sleep, the risk of heart failure and other cardiovascular problems can be lowered significantly.
Talk to a cardiologist if you have any questions related to heart health.