Nocturnal High Blood Pressure : Causes, Diagnosis, and Treatment

1. What is Nocturnal High Blood Pressure?

   Nocturnal high blood pressure is an elevated blood pressure experienced by a person during the night or during sleep.⁽¹⁾ It is characterized by a blood pressure reading that exceeds the normal range during the nighttime hours.

   According to American Heart Association a person’s blood pressure should not exceed more than 120/80 mmHg, where 120 is the systolic and 80 is the diastolic blood pressure reading.⁽²⁾

   Blood pressure may fluctuate throughout the day with the levels falling lower during sleep and higher during wakefulness.

   Nocturnal high blood pressure in a person can have negative health implications including stroke, heart attack, and kidney failure.

2. Importance of Understanding the Causes of Nocturnal High Blood Pressure

   It is essential to have an understanding of the causes of high blood pressure for accurate diagnosis, effective treatment planning, risk reduction, patient education, and future advancements. Identifying and addressing the specific factors contributing to elevated blood pressure during sleep can be helpful for the healthcare provider to improve the outcome and promote cardiovascular health in people with nocturnal hypertension.

   Investigation of the causes can also contribute to the ongoing research and advancements in the field.

   Overall, an understanding of the cause of nocturnal high blood pressure can improve the outcome and quality of life of an individual with nocturnal hypertension.

The causes of nocturnal high blood pressure are multifactorial and may vary.

1. Sleep-Related factors

   • Sleep Apnea: Obstructive sleep apnea is a sleep disorder that pauses breathing during sleep and is associated with repetitive episodes of oxygen deprivation. It may increase the blood pressure levels during the night.
   • Insomnia and Poor Sleep Quality: Chronic sleep disturbance such as poor sleep quality or insomnia may disrupt normal blood pressure and contribute to nocturnal hypertension.
   • Sleep Deprivation: Lack of sufficient sleep or chronic sleep deprivation can increase the activity of the sympathetic nervous system. This in turn can raise blood pressure levels during sleep.

2. Neurological factors

   • Sympathetic Nervous System Activity: Increase in the activity of the sympathetic nervous system during sleep may elevate blood pressure. This can be caused by various factors including stress, anxiety, and certain medical conditions.
   • Disruption of Circadian Rhythm: The internal circadian rhythm in the body plays a role in regulating blood pressure. Disruption in the circadian rhythm due to shift work or irregular sleep patterns can elevate the nocturnal blood pressure.

3. Hormonal factors

   • Renin-Angiotensin-Aldosterone System: Renin-angiotensin-aldosterone system regulates blood pressure. An imbalance in it can contribute to nocturnal hypertension.
   • Cortisol Levels During Sleep: Cortisol is a hormone that has higher levels in the morning and lower levels at night.⁽⁷⁾ Abnormalities in cortisol regulation can impact the blood pressure regulation.

4. Medication and Substances

   • Antihypertensive Medication Timing: The timing of antihypertensive medications can influence blood pressure control during sleep. Sometimes an adjustment in medication timing is necessary to optimize nighttime blood pressure control.
   • Stimulants: Certain substances including caffeine, nicotine, and alcohol can affect the blood pressure level during sleep.

5. Lifestyle Factors

   • Obesity: Excess body weight and obesity are associated with increased hypertension and can affect it at night as well.
   • Physical Inactivity: Lack of regular sleep or a sedentary lifestyle can contribute to elevated blood pressure during the night.
   • Alcohol Consumption: Consuming excess alcohol and smoking can increase blood pressure levels during sleep.

   All these factors can interact and influence each other and contribute to the development of nocturnal high blood pressure.

   The various risk factors associated with nocturnal hypertension include hypertension, a sedentary lifestyle, nocturia, kidney disease, stress, high salt intake, and obstructive sleep apnea.^{(1, 6)}

Several steps are involved in the diagnosis and treatment of high blood pressure. It is important for identifying the underlying cause and implementing an effective treatment plan.

1. Diagnosis

   The diagnosis involves the following:

   • Blood Pressure Monitoring: To diagnose nocturnal high blood pressure, the patient is recommended ambulatory blood pressure monitoring or home blood pressure monitoring. It involves wearing a portable device that measures blood pressure at regular intervals throughout the night. This helps in assessing blood pressure patterns during sleep and identifying nocturnal blood pressure.
   • Identifying Underlying Cause: Once diagnosed with nocturnal blood pressure, the doctor may further look for the factors that may be contributing to its occurrence. It involves taking the complete medical history, doing a physical examination, and running a few diagnostic tests for sleep apnea and hormonal assessment.

2. Treatment of Nocturnal High Blood Pressure

   The treatment of nocturnal hypertension involves:

   • Lifestyle Modifications: Lifestyle modifications include losing weight as it may help reduce blood pressure levels during sleep. This involves eating a healthy diet and increasing physical activity.⁽⁴⁾ Engaging in physical activity is important as aerobic exercises can lower blood pressure and improve overall cardiovascular health. Practicing good sleep is another good lifestyle modification. It includes maintaining a consistent sleep schedule, creating a conducive sleep environment, and managing stress. This can improve sleep quality and reduce nocturnal hypertension. Limiting alcohol consumption and quitting smoking can contribute to lowering blood pressure levels during sleep.
   • Medication and Therapeutic Intervention: Antihypertensive medications are given to control blood pressure levels during sleep.⁽³⁾ CPAP (continuous positive airway pressure therapy) is recommended if sleep apnea is identified. It involves wearing a mask during sleep that delivers a continuous flow of air to keep the airway open and improve breathing. This can be helpful in reducing blood pressure levels associated with sleep apnea. Additional interventions may be recommended depending on the specific underlying cause. These may include treating hormonal imbalances and addressing neurological factors that contribute to nocturnal hypertension.
   • Regular Monitoring and Follow-up: A person diagnosed with high blood pressure should get regular blood pressure check-ups to monitor the progress and adjust treatment as needed. A periodic blood pressure measurement during sleep may be needed along with regular visits to the doctor. People with nocturnal high blood pressure need to adhere to the recommended treatment plan and communicate with the healthcare provider regarding any changes in the symptoms.

There are significant complications and long-term effects of nocturnal high blood pressure.⁽⁵⁾ These include:

• Increased risk of cardiovascular diseases.
• Damage may be caused to the heart, brain, kidney, and blood vessels. A continuous strain on these organs can result in hypertensive heart disease, cognitive impairment, chronic kidney disease, and vascular complications.
• Negative impact on overall health and well-being of an individual.
• Exacerbation of other health conditions including sleep apnea and diabetes.
• Medication resistance and need for other alternative treatment approaches.
• Impact on mental health which may lead to anxiety, stress, and depression.

It is important to recognize the potential complications and long-term effects of nocturnal high blood pressure and emphasize proper diagnosis, management, and treatment. Regular monitoring, adherence to treatment, lifestyle modifications, and collaboration with healthcare professionals are key factors in mitigating the complication of high blood pressure.

Blood pressure usually decreases at night. If it does not decrease enough or rise sometimes, it is known as nocturnal high blood pressure. It is important to know the cause of the condition and work out an effective treatment plan.

Managing nocturnal high blood pressure is essential to reduce the risk of cardiovascular diseases and target organ damage. This can be helpful in improving the overall health and quality of life.

Further research and advancement in understanding the causes and treatment of nocturnal high blood pressure can lead to improved intervention and outcomes for individuals with this condition. Prioritizing the diagnosis and management of nocturnal hypertension can be helpful in promoting better cardiovascular health.