Is it normal for blood pressure to fluctuate throughout the day? —O.B., Bristol, Conn.

Yes. Blood pressure—particularly the systolic pressure (upper number)— rises and falls throughout the day in response to what you’re doing, feeling, and thinking. Caffeine, exercise, smoking, and stress temporarily increase blood pressure, while meditation and other calming activities, such as yoga, typically lower it.

In a healthy person, blood pressure should also follow a certain daily rhythm, peaking in the morning, slowly declining in the afternoon and evening, falling even lower during the night, and again rising to greet the dawn. Blood pressure that doesn’t follow that pattern could be an early warning sign of cardiovascular disease, which is why it’s important for people monitoring their blood pressure at home to take several readings a day at the same times.