Measuring blood pressure (BP) actually involves two measurements: systolic BP and diastolic BP. Measurements are made in millimetres of mercury (mmHg). It is important to maintain normal blood pressure in order to avoid heart attack or stroke.
Systolic Versua Diastolic
The systolic measurement is the peak BP your heart reaches as it beats; the diastolic measurement is the low point of BP as your heart relaxes between beats. Overall BP measurements are expressed as the ratio of systolic to diastolic (e.g., 130/70 mmHg).
Normal BP ranges between 90/60 and 140/90 mmHg. Ideal BP is 120/80 mmHg. Even within the normal range, those with higher BP measurements have greater health risks than those with lower ones.
High BP, also called hypertension, is classified as above 140/90 mmHg. Those with high BP are at risk of heart attack or stroke due to increased strain on the heart, blood vessels or both.
Low BP, or hypotension, is classified as 90/60 mm/Hg or lower. Low BP is usually not a concern except in extreme cases, including especially sudden drops in measurements.
BP may change significantly over a day, week, or month, depending on mental factors such as stress and anxiety as well as physical factors such as time of day, diet and sleep. This means you should take multiple measurements during the day, a couple of times a month, to determine your average BP.