Diastolic pressure, the resting force of blood within the blood vessels represented by the bottom number of a pressure reading, can go up or down depending on a number of things. Changes can be rapid and temporary, or the number may have an overall increase or decrease over time. Some factors that can affect diastolic pressure levels in the short term include stress, changes in posture, and exercise. Factors that can cause it to shift in the longer term are family history, diet and lifestyle, and the person's overall health. One factor that has a significant negative impact in both the short and long term is smoking.
A number of things can make diastolic pressure change fairly rapidly, so taking several measurements may be the best way to get a true idea of its level in a particular person. Pressure levels normally shift throughout the day, usually going down at night and rising in the morning. Someone who is feeling high levels of stress or anxiety and is very tense may find that his or her diastolic pressure is higher than usual. A person who has just exercised and then has his or her blood pressure measured may find that it is different than normal. Even a change in posture, for example going from lying down to standing, can cause it to change quickly.
Certain factors can also cause diastolic pressure levels to go up or down in a more permanent fashion. Family history is often very predictive of blood pressure levels, as people with close relatives who have high or low blood pressure often tend to have similar levels. Lifestyle can also play a big role; for example, those who eat an unhealthy diet or are overweight or obese may tend to have higher levels, while those who exercise regularly often have lower levels. Overall health may also play a role, particularly if patients have certain issues like heart disease or need to be on medications that affect blood pressure.
Smoking is one behavior that can have a lot to do with diastolic pressure levels, both in the short and long term. Right after smoking, the resulting nicotine in the blood can cause a rapid increase in pressure. Long term, smokers may also be at greater risk for high blood pressure, with overall increases in both diastolic and systolic pressure.