It's quite normal for blood pressure to vary throughout the day. If you measure your blood pressure during the day, it will certainly differ from your nighttime blood pressure.
However, whether this is okay or not depends on what kind of variation that is. Is your blood pressure higher at night than in the daytime hours? If so, then you’ve got a problem you need to tackle.
What's the Usual Blood Pressure Daily Pattern?
Well, in general, blood pressure rises a couple of hours before you wake up in the morning. From here on, it goes on rising throughout the day, with its peak happening at midday.
After this, it should start dropping so that in the late afternoon and evening hours, your pressure is lower than in the daytime hours. Also, your blood pressure is normally lower while you sleep. (this one's called nocturnal blood pressure).
What Kind of Patterns Signalize Abnormal Blood Pressure?
Abnormal blood pressure may look like this:
- High blood pressure in the early morning;
- High blood pressure at night or during sleep;
- Your blood pressure drops less than 10% during the night (this is also called non-dipping blood pressure or nocturnal BP decline).
It's important to pay attention to signs of abnormal behaviour in your blood pressure, especially at night, because, if left untreated, it can increase your risk of heart disease.
Why Is High Blood Pressure Dangerous?
Research finds that nighttime blood pressure higher than the one measured in daytime hours is linked to higher chances of heart failure and cardiovascular disease (including stroke). The same goes for people who keep their high blood pressure controlled in the daytime but experience more extreme dips in their blood pressure during sleep.
Because people normally don't measure blood pressure at night, nocturnal hypertension (nighttime high blood pressure) usually goes unnoticed until a lot of damage has already been done.
So, if you measure systolic blood pressure 20 mm Hg above your regular daytime systolic blood pressure reading, then it's time to sound the alarm.
Why Does Blood Pressure Rise at Night?
The reason why you may be experiencing elevated nighttime blood pressure depends on several different behavioral and risk factors.
For example, hot weather and high summer temperatures can also cause your blood pressure to rise during the night.
Certain behaviour factors can also be the culprit, such as:
- Too much salt in your diet (aka high salt intake);
- Not enough physical activity;
- Lack of sleep or low sleep quality;
- Working a night/graveyard shift.
Already present risk factors such as obesity, stress, and aging can also be the reason behind your nocturnal blood pressure, as can:
- Hypertension (chronic high blood pressure);
- Salt sensitivity;
- Obstructive sleep apnea.
Also, underlying diseases can cause nocturnal blood pressure, such as:
- Certain diseases to the endocrine system (like Cushing syndrome, renovascular hypertension);
- Chronic kidney disease;
- Heart failure;
- Diseases of the CNS - central nervous system, like depression or a stroke;
- Restless leg syndrome.
What Can You Do About It?
If you suspect that you may have any kind of issues with your blood pressure, then you should talk to a doctor as soon as possible. But what's also very important are regular checkups.
While low blood pressure is generally not considered dangerous, high blood pressure (or hypertension) is often called "the silent killer." This is because it can often go unnoticed and cause all kinds of damage to your body. Regular checkups will ensure that this doesn't happen and that you've caught the high (nocturnal) blood pressure before it gets serious.
Your doctor will tell you what to do and what medications to take. In general, though, it's good to stick to a healthy sleeping schedule, a lower amount of salt intake in your diet, regular exercise, less stress, less alcohol, and no smoking.