What happens to your blood pressure when you're not measuring it?

Your blood pressure is constantly changing

Blood pressure isn't a fixed number. It rises and falls as your body responds to daily life, whether you're rushing for a train, dealing with a stressful meeting, drinking coffee, or relaxing on the sofa. Stress, activity, sleep, and diet can all influence it.

These changes are often normal, but looking at readings taken over time can help healthcare professionals understand your blood pressure more fully than a single measurement.

What happens to your blood pressure while you sleep?

For many people, blood pressure falls by around 10-20% during sleep compared with daytime levels. This is called nocturnal dipping and forms part of the body's natural daily rhythm.¹

Not everyone follows this pattern. Some people have a smaller fall overnight, while others have higher blood pressure during sleep than when awake. Research has associated unusual night-time blood pressure patterns with cardiovascular risk.¹

Because most home monitors require you to sit quietly and take a reading, checking blood pressure while you're asleep isn't straightforward. Healthcare professionals can use 24-hour ambulatory monitoring - a portable cuff that inflates at intervals, including overnight - when a fuller assessment is needed.

Can your blood pressure be high without you knowing?

Yes. High blood pressure - or hypertension - often has no noticeable symptoms. The World Health Organization (WHO) estimates that around 44% of adults with hypertension worldwide are unaware they have it.²

High blood pressure can increase the risk of heart attack, stroke, and kidney disease. That's why checking it matters even if you feel well.³

The NHS advises adults aged 40 and over to have their blood pressure checked at least every five years, or more often if recommended. If your readings are repeatedly high, speak to your GP. ³

A fuller picture of your blood pressure

Home blood pressure monitoring and clinician-prescribed 24-hour ambulatory monitoring can help reveal patterns that may not appear during an appointment. New wearable technology offers another way to collect readings during everyday life.

Hilo is a clinically validated blood pressure monitoring system that takes automatic readings during the day and night when measurement conditions are suitable. Its wrist-worn band uses optical sensing technology, while an upper-arm cuff is used for initial calibration and recalibration every 30 days.

The Hilo App brings readings together to show blood pressure patterns and averages over time. Reports can be shared with a healthcare professional to support conversations about cardiovascular health.

The bigger picture

One blood pressure reading can be useful. Understanding how readings vary across days and nights can add context and help you have a more informed conversation with your GP.

Discover Hilo

Explore how Hilo's automatic day-and-night measurements and app-based reports can help you understand your blood pressure patterns.