Blood pressure has a daily pattern.
Usually, blood pressure starts to rise a few hours before a person wakes up. It continues to rise during the day, peaking in midday. Blood pressure typically drops in the late afternoon and evening. Blood pressure is usually lower at night while sleeping. The blood pressure measurement at night is called nocturnal blood pressure.
Examples of an irregular blood pressure pattern include:
- High blood pressure during the night.
- High blood pressure early in the morning.
- Less than 10% drop in blood pressure overnight, called nondipping blood pressure.
A rise in blood pressure overnight to early morning has been linked to an increased risk of heart disease.
An irregular blood pressure pattern also could mean that you have:
- Poorly controlled high blood pressure.
- Obstructive sleep apnea.
- Kidney disease.
- Diabetes.
- Thyroid disease.
- A nervous system disorder.
Poor diet, lack of exercise and certain lifestyle factors can affect blood pressure pattern, including:
- Night-shift work.
- Smoking.
- Overweight or obesity.
- Stress and anxiety.
- Not taking medicines for blood pressure or sleep apnea as directed, or ineffective treatment.
Your healthcare professional can tell you if an irregular daily blood pressure pattern needs treatment. Sometimes, a person's blood pressure rises simply when seeing a healthcare professional. This is called whitecoat hypertension.
A 24-hour blood pressure monitoring test can be done to measure blood pressure at regular time periods over 24 hours. The test is called ambulatory blood pressure monitoring. It offers a detailed look at blood pressure changes over an average day and night.