Why Is My Blood Pressure Higher In The Evening

You may have checked your blood pressure at home or in a clinic and noticed that it’s higher in the evening. This is normal for most people, as blood pressure varies throughout the day. It increases in the evening and reaches its lowest values during sleep. Certain things you do might also contribute to this increase. However, you should contact your doctor if your blood pressure is above 130/80mmHg during the day or above 110/65mmHg during sleep. 

Understanding blood pressure

Blood pressure is the force on your arteries when your heart pumps blood. It has two values: systolic blood pressure (the top number) and diastolic blood pressure (the bottom number). Systolic blood pressure is the pressure when your heart beats, while diastolic blood pressure is the pressure when your heart relaxes.¹ 

Normal blood pressure lies between 90/60mmHg and 120/80mmHg. High blood pressure or hypertension is blood pressure above 140/90mmHg or 150/90mmHg for people 80 years and above. Some doctors diagnose high blood pressure at 130/80mmHg. High blood pressure is not a disease but it puts a strain on your heart and blood vessels and increases your risk of cardiovascular diseases.^1,2

Signs and symptoms

According to the NHS, about a third of adults in the UK have high blood pressure. Many people won’t know that they have high blood pressure. And many don’t manage it well. This is because high blood pressure rarely shows signs. But there are some signs it shows:

• Dizziness 
• Headaches
• Nosebleeds
• Chest pain
• Blurred vision
• Breathlessness³

Confirm with your doctor if you experience any of these symptoms, as they could indicate other health conditions. The only way to confirm that you have high blood pressure is by measuring it. 

You should check your blood pressure every 5 years if you are over 40. And if you have a risk of high blood pressure, you should check it every year. Take your blood pressure drugs and make lifestyle changes if you are hypertensive.^1,2,3 

Causes and risk factors

High blood pressure develops over time so it's difficult to identify its causes. But some risks increase your chance of getting hypertension: 

• Age above 65
• A diet low in fruit and vegetables but high in salt and fat
• Physical inactivity
• Inadequate sleep
• Obesity 
• Smoking
• High alcohol and caffeine intake
• A family member with hypertension.^1,2

There are also health conditions and medications that cause hypertension. Consult with your doctor for a proper evaluation of your hypertension risk.   

Why is blood pressure higher in the evening? 

It’s normal for your blood pressure to vary throughout the day as it has a circadian rhythm. The circadian rhythm synchronises your body’s activities based on cues from the environment such as light/darkness. 

Typically, blood pressure rises when you wake up in the morning. It stays high in the morning and falls slightly in the early afternoon. It rises again in the early evening and decreases in the late evening. Blood pressure drops to its lowest values during sleep and remains low until you wake up.⁴ 

This rhythmic variation of blood pressure is influenced by certain behaviours. They may cause hypertension at specific times in the day.

Mental and physical stress: Stress-related to housework or jobs can cause daytime hypertension.

Drinking alcohol: Habitual drinking increases the risk of morning hypertension. 

Smoking: Your blood pressure shoots up when you smoke. And daytime blood pressure is usually higher in smokers than non-smokers. It's also higher on smoking days than non-smoking days. As people don't usually smoke in hospitals, their possible hypertension often goes unnoticed.

Salt intake: High salt intake increases blood pressure of salt sensitive people, especially. Salt restriction reduces daytime and nighttime blood pressures in hypertensive people.

Caffeine vs cocoa intake: Shortly after taking caffeinated drinks your blood pressure might increase. This increase is larger for hypertensive people. Cocoa reduces blood pressure in the long term.

Eating: Blood pressure increases during meals and reduces for more than 2 hours after a meal. This reduction is often larger in older and hypertensive people than people with normal blood pressure. It's also larger after high-carbohydrate meals than after high-fat meals.

Potassium, magnesium, and calcium consumption. These nutrients reduce blood pressure and help manage hypertension. You can take them as supplements. You can also eat fruits and vegetables rich in potassium and magnesium and dairy products rich in calcium.

Exercise: Blood pressure usually increases during exercise due to the strain. It drops for several hours after exercise.

Bathing: Blood pressure usually increases at the beginning of a hot bath and then falls. It reduces further after a bath and returns to its normal level after about an hour. These effects are linked to heat and immersion in water.⁴

Although blood pressure is usually higher in the early evening, these behaviours can increase (or reduce) your evening blood pressure. Let your doctor know if your evening blood pressure is higher than 130/80mmHg as this indicates a possible hypertension.

Is high blood pressure common at night?

Nighttime high blood pressure is not common. Most people have their lowest blood pressure when they sleep. However, some factors can cause short-term blood pressure surges during sleep such as obstructive sleep apnea, rapid eye movement sleep, and waking up at night (to pee, for example).

Blood pressure usually shows 4 patterns during sleep.

Normal dipper pattern: Here, blood pressure dips by 10–20% of its daytime value. This is common for most people including hypertensive people without organ damage. Hypertensive people with organ damage tend to have less dipping during sleep. 

Non-dipper pattern: Blood pressure reduces during sleep but not up to 10% of its daytime value.

Extreme dipper pattern: Blood pressure reduces to more than 20% of its daytime value.

Riser pattern: Blood pressure increases during sleep.^5,6 

A blood pressure of over 120/70mmHg is seen as nocturnal hypertension (110/65mmHg per the American heart association). Nocturnal hypertension can exist regardless of your daytime blood pressure. People with normal blood pressure during the day (<130/80 mmHg) have a masked nocturnal hypertension.

Nocturnal hypertension and unfavourable patterns (non-dipper, extreme dipper and riser) are risks for cardiovascular diseases in normal and hypertensive people. This risk is more profound than daytime hypertension.^6,7  

If you have a hypertension risk, It is recommended that you measure your blood pressure at different times of the day. This gives you and your doctor a better picture of your blood pressure. You can measure your blood pressure outside the clinic and at night using an ambulatory blood pressure monitor. Nighttime blood pressure is usually an average of 6 or more measurements done during sleep.^6,8 You can measured this 2 night in a week.⁸  

Ways to stabilize your blood pressure at night

Taking blood pressure drugs is the best way to stabilise your nighttime blood pressure. Your doctor might prescribe

• Angiotensin-converting enzyme inhibitors (ACEI) 
• Angiotensin receptor blockers (ARB)
• Calcium channel blockers (CCB)
• Diuretics 

These drugs are often combined: ACEI or ARB with CCB or diuretics. Taking your drugs at night may control nocturnal hypertension or revert non-dipperriser patterns.⁷ Discuss the best time to take your drugs with your doctor.

There are also lifestyle changes you can make to stabilise your blood pressure at night:

• Restrict salt intake especially at night
• Exercise in the evening 
• Reduce weight if you are obese or overweight
• Quit smoking 
• Reduce drinking alcohol and caffeinated drinks^4,9

When to contact your doctor

Abnormal nighttime blood pressures are often unnoticed as they are not usually checked at the clinic. So, contact your doctor if you observe an increase, a less than 10% decrease or a more than 20% decrease in your blood pressure at night. You also need to contact your doctor if your nighttime blood pressure is more than 110/65mmHg or daytime blood pressure above 130/80mmHg.⁶

People with diabetes, chronic kidney disease, obesity, obstructive sleep apnea, autonomic dysfunction, and endocrine hypertension have a high risk of nocturnal hypertension and non-dipping/riser nighttime blood pressure patterns.⁹ You need to let your doctor know if you have any of these diseases or if you are hypertensive.

Summary

It’s normal for your blood pressure to be higher in the early evening. These might be due to certain behaviours that affect your blood pressure in the evening and throughout the day. But you should let your doctor know if your blood pressure is above  130/80mmHg. High blood pressure at night is not common as blood pressure should be at its lowest during sleep.