Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps. It naturally changes throughout the day, so one reading may be different from the next.
Activity, sleep, emotions, meals and even the time of day can all affect the numbers.
Small changes are usually normal. However, repeated large swings or blood pressure that stays too high can be a reason to talk with a doctor. Over time, poorly controlled high blood pressure can damage blood vessels and increase the risk of heart disease, stroke, kidney problems and other serious conditions.
Stress is one common reason blood pressure can suddenly rise. When a person feels frightened, angry or under pressure, the body releases stress hormones that make the heart beat faster and blood vessels tighten. This response is useful during an emergency, but frequent stress may make blood pressure harder to control.
Finding healthy ways to manage stress may help. Walking, slow breathing, relaxation exercises, spending time with other people and enjoyable activities can all help the body settle after stressful situations. Getting enough sleep is also important because poor sleep has been linked to problems with blood pressure.
Food can make a major difference as well. Eating a lot of salt can cause the body to hold extra fluid, which can raise blood pressure in people who are sensitive to salt. Packaged and restaurant foods are often major sources because they can contain large amounts of salt even when they do not taste especially salty.
A well-studied eating plan called the DASH diet was developed to help control blood pressure. It emphasizes vegetables, fruit, whole grains, beans, nuts and low-fat dairy foods while limiting foods high in salt, added sugar and saturated fat. Research has shown that this style of eating can lower blood pressure.
Regular physical activity can also help the heart and blood vessels work more efficiently. Blood pressure normally rises while a person exercises because working muscles need more blood and oxygen. With regular activity, however, resting blood pressure can fall and the cardiovascular system can become healthier.
Health guidelines commonly recommend about 150 minutes of moderate physical activity each week for adults who are able to exercise safely. Brisk walking, cycling and swimming are examples. People who have heart problems or other medical conditions may need to ask a health professional what level of exercise is appropriate.
Medicines can sometimes explain unexpected changes in blood pressure. Certain cold and flu products, anti-inflammatory pain medicines and other drugs can raise blood pressure in some people. Prescription blood pressure medicines can also produce different readings depending on the dose, timing and whether doses are missed.
Home monitoring can help reveal patterns that may not appear during a single doctor’s visit. For a more reliable reading, a person should sit quietly for several minutes, keep the arm supported and use a properly fitting cuff. Exercise, smoking and caffeine shortly before a measurement can temporarily change the result.
It is also useful to measure blood pressure under similar conditions each time and record the results. A series of readings gives a doctor much more information than one unusually high or low number. People should not change or stop prescribed blood pressure medicine based only on home readings without medical advice.
Body weight can also affect blood pressure. For people who are overweight, even modest weight loss may help reduce it. Combining weight management with regular activity, a healthy diet, less salt and limited alcohol can provide benefits that add up over time.
Large changes in blood pressure can sometimes have causes that need medical investigation, including problems with the heart, kidneys, hormones or nervous system. Dehydration and some illnesses can also cause blood pressure to fall unexpectedly. This is why frequent or unexplained swings should not simply be ignored.
Blood pressure that changes during the day is not automatically dangerous, but the overall pattern matters. Healthy food, regular movement, stress management and careful home monitoring can all help keep it under control. Working with a health professional can also identify hidden causes and help protect the heart, brain and kidneys for the long term.
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