People with supine hypertension have high blood pressure while lying down. This can happen when your autonomic nervous system (ANS) doesn’t function properly. The treatment involves lifestyle changes and medications.

Supine hypertension is when you have high blood pressure while lying down. You have supine hypertension if you have one or both of the following after 5 minutes of lying down:

  • a systolic blood pressure of 140 millimeters of mercury (mm Hg) or higher
  • a diastolic blood pressure of 90 mm Hg or higher

For reference, the American Heart Association defines normal blood pressure as a systolic blood pressure of less than 120 mm Hg and a diastolic blood pressure of less than 80 mm Hg.

Your blood pressure can change slightly based on your body positioning. But there’s some disagreement among researchers as to whether your blood pressure is higher or lower when lying down.

Below, we’ll take a closer look at supine hypertension, what causes it, and how it’s diagnosed and treated.

Supine hypertension occurs when your autonomic nervous system (ANS) doesn’t function as it should. Your ANS regulates involuntary body functions such as:

  • blood pressure
  • heart rate
  • body temperature
  • breathing
  • digestion
  • urination
  • sexual arousal

When ANS dysfunction affects blood pressure, it often leads to orthostatic hypotension. This is a sudden drop in blood pressure when you stand up, which can cause dizziness, lightheadedness, or fainting.

Supine hypertension often occurs with orthostatic hypotension. About 50% of people who have neurogenic orthostatic hypotension — orthostatic hypotension due to a neurological condition — also have supine hypertension.

Neurogenic orthostatic hypotension and supine hypertension are often associated with the effects of certain neurodegenerative disorders. These are conditions that cause gradual damage to the nervous system.

Two such disorders in which supine hypertension is prevalent are Parkinson’s disease (PD) and multiple system atrophy (MSA). Supine hypertension occurs in up to 46% of people with PD and 37% of people with MSA.

Most of the time, supine hypertension does not have any symptoms. That means you may not know you have it.

When symptoms are present, they can include:

  • headache
  • nocturia (increased urination at night), which can disrupt your sleep
  • worse orthostatic hypotension in the morning

Although more research is needed, several potential long-term risks are believed to be associated with supine hypertension. These include:

Supine hypertension severity

There are three levels of supine hypertension severity:

  • Mild supine hypertension is when you have a systolic blood pressure of 140 to 159 mm Hg or a diastolic blood pressure of 90 to 99 mm Hg.
  • Moderate supine hypertension is when you have a systolic blood pressure of 160 to 179 mm Hg or a diastolic blood pressure of 100 to 109 mm Hg.
  • Severe supine hypertension is when you have a systolic blood pressure of 180 mm Hg or higher or a diastolic blood pressure of 110 mm Hg or higher.

In people who also have orthostatic hypotension, the severity of supine hypertension is associated with that of orthostatic hypotension. This means that people who have more severe orthostatic hypotension typically have more severe supine hypertension.

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To diagnose supine hypertension, a doctor will first take your medical history and do a physical exam. They may also do a neurological exam, during which they’ll assess factors such as your balance, reflexes, and mental status.

Your doctor will likely measure your blood pressure before and 5 minutes after you lie down. They’ll be looking at whether your blood pressure increases significantly after you lie down.

If you have not received a diagnosis of orthostatic hypotension, other tests may be helpful. These may include measuring your blood pressure both before and after standing or doing a tilt-table test.

If tests in your doctor’s office suggest supine hypertension, your doctor may ask you to do 24-hour blood pressure monitoring. This test can provide information on how your blood pressure fluctuates throughout the day, including while you’re sleeping.

The treatment for supine hypertension can be tricky because many people with supine hypertension also have orthostatic hypotension.

The medications used to treat orthostatic hypotension can make supine hypertension worse, and lowering your blood pressure to treat supine hypertension can make orthostatic hypotension worse.

Therefore, treatment will focus on managing orthostatic hypotension, often with medications, while taking steps to minimize supine hypertension.

Much of the treatment for supine hypertension focuses on the nighttime hours. This is because, if you have supine hypertension, your blood pressure may be high for an extended period while you sleep.

Sleeping in a reclined position instead of a fully flat position may help with supine hypertension at night. Additionally, taking a short-acting blood pressure medication at night may help lower your blood pressure while you sleep.

There’s no surefire way to prevent supine hypertension. But if you have supine hypertension, you can take the following steps to help prevent it from worsening, particularly at night:

  • Avoid lying down after taking medications for orthostatic hypotension, as these medications can make supine hypertension worse.
  • Take your last daily dose of orthostatic hypotension medication 3 to 4 hours before bedtime.
  • Sleep in an elevated position, such as by propping yourself up by 30 degrees (6 to 9 inches) or sleeping in a recliner.
  • Eat a high carb snack before bed. This can help lower your blood pressure by dilating your blood vessels and directing blood flow to your abdomen.

Supine hypertension is when you have high blood pressure while lying down. Many people who have supine hypertension also have neurogenic orthostatic hypotension.

There’s no standard treatment for supine hypertension. Treatment typically involves lifestyle changes and potentially the use of short-acting blood pressure medications at night.