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Categories > Heart Health > Blood pressure

The ups & downs of blood pressure
When pressure drops
What’s normal

How to get an accurate reading
How to get an accurate reading

Before a blood pressure check, take these steps:

  • Avoid caffeine and cigarettes for 30 minutes before the test.
  • Wear short sleeves.
  • Use the bathroom. A full bladder can affect your results.
  • Sit in a chair with your back supported and feet flat on the floor for at least five minutes.
  • Rest your arm on a table at the level of your heart.

When your healthcare provider measures your blood pressure, the results represent your levels at the time of the reading. But blood pressure, like heart rate, respiration and other body functions, changes throughout the day.

Some of these changes occur naturally. When you sleep, your blood pressure typically goes down. It starts to rise again when you wake up and then peaks around midafternoon. Throughout the afternoon and evening, it starts to drop again.

On top of these natural fluctuations, blood pressure can spike or slump in response to outside factors, including:

  • exercise or physical exertion
  • certain medications, such as corticosteroids, pain relievers and decongestants
  • some herbal supplements, such as St. John’s wort
  • foods or supplements that contain licorice
  • caffeine
  • tobacco
  • stress and other emotions

What’s more, simply having your blood pressure tested can lead to “white-coat hypertension,” in which nervousness around your doctor or nurse (who have traditionally worn white coats) raises blood pressure. One abnormal reading, however, doesn’t necessarily mean you have high blood pressure. The American Heart Association recommends at least three doctor visits, one to several weeks apart, to confirm a hypertension diagnosis.

When pressure drops

Older adults are more likely to experience hypotension, or a quick drop in blood pressure, usually when they stand up. This pressure drop can lead to temporary dizziness or light-headedness, which increases the risk of falling. Blood pressure medications can also cause hypotension. Since medications don’t always work a full 24 hours, they can cause pressure fluctuation. If you take blood pressure medication, take it exactly as directed and let your doctor know if you experience any symptoms of a blood pressure slump.

What’s normal

Event-related changes in blood pressure are generally considered normal and nothing to be alarmed about. In fact, a recent Johns Hopkins study found that the spike in blood pressure during moderate exercise doesn’t harm the hearts of those with mild hypertension.

However, frequent, dramatic blood pressure changes can cause as much damage as persistent hyper-tension. If you experience fluctuations like this, your healthcare provider may want to evaluate them with a 24-hour blood pressure monitoring test. This gives a more accurate picture of your daily blood pressure changes and whether they’re cause for concern.