Blood pressure: Does it have a daily pattern?

Blood pressure has a daily pattern.

Usually, blood pressure starts to rise a few hours before you wake up. It continues to rise during the day, peaking in midday. Blood pressure normally drops in the late afternoon and evening. Blood pressure is normally lower at night while you're sleeping. Your blood pressure measurement at night is called nocturnal blood pressure.

Examples of an abnormal 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 (nondipping blood pressure)

A rise in blood pressure overnight to early morning has been linked to an increased risk of heart disease.

An abnormal blood pressure pattern could also 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 your blood pressure pattern, including:

• Night-shift work
• Smoking
• Overweight or obesity
• Stress and anxiety
• Not taking medications for blood pressure or sleep apnea as directed, or ineffective treatment

Your doctor can tell you if an abnormal daily blood pressure pattern may need treatment. Sometimes, a person's blood pressure rises simply when seeing a doctor. This is called whitecoat hypertension.

A 24-hour blood pressure monitoring test can be done to measure your blood pressure at regular time periods over 24 hours. The test, called ambulatory blood pressure monitoring, provides a detailed look at your blood pressure changes over an average day and night.

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