When you're asleep your blood pressure is generally lower than while you're awake. This is totally normal and is known as nocturnal dipping. The drop in both your systolic (the top number) and diastolic (bottom number) blood pressure can be up to 20% lower than your readings in the day time.

Does sleeping make blood pressure lower?

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.

How much does your blood pressure go down when you sleep?

Compared to the overall daytime blood pressure pattern, "blood pressure is generally about 10% to 20% lower during sleep.