Blood pressure: Does it have a daily pattern?

Like many body functions, blood pressure has a daily (diurnal) pattern. Blood pressure normally decreases at night while you sleep. When you get out of bed in the morning, your blood pressure starts to increase and peaks about midafternoon. In the late afternoon and evening, your blood pressure starts to decrease again.

Factors that may cause an abnormal daily pattern, such as high blood pressure in the morning, include:

• Poorly controlled high blood pressure
• Sleep apnea
• Tumors of the adrenal gland
• Kidney disease
• Certain medications, such as corticosteroids
• Night-shift work
• Caffeine use
• Tobacco use
• Too much stress

Blood pressure lowering medications also can alter this pattern because some may not last a full 24 hours.

Your doctor can evaluate the significance of an abnormal diurnal blood pressure pattern. He or she may recommend a 24-hour blood pressure monitoring test. The device used for this test measures your blood pressure at regular intervals over a 24-hour period and provides a more accurate picture of blood pressure changes over a typical day and night.