According to the American Heart Association, normal blood pressure is 120/80 or a little below. Blood pressure varies depending on stress, physical condition, medications, food and drink, activity, body position, and time of day. It is usually lowest at night.
Systolic
Systolic pressure is the pressure in arteries when the heart beats. It is represented by the first number in a blood pressure measurement. In a measurement of 120/80, systolic pressure is 120.
Diastolic
Diastolic pressure is the pressure in arteries when the heart rests between beats. It is represented by the second number in a blood pressure measurement. In a measurement of 120/80, diastolic pressure is 80.
High Blood Pressure
According to the American Heart Association, one in three Americans has high blood pressure. A single high reading does not mean a diagnosis of high blood pressure, but it should be monitored.
Low Blood Pressure
MayoClinic.com explains that some doctors consider systolic pressure below 90 and/or diastolic pressure below 60 to be low blood pressure. A low reading with no symptoms such as dizziness may be no cause for concern. If blood pressure is severely low, it can lead to shock, which is potentially fatal.
