Your blood pressure should drop by 10–20% when you sleep: Why the ‘night-time dip’ matters

Cardiologist Dr Alok Chopra recently shed light on how our blood pressure (BP) may appear normal during the day — but what happens to it at night?

In an Instagram post, he explained, “While you sleep, BP should normally drop by around 10%. If it doesn’t, it can increase the risk of stroke and organ damage. Broken sleep? Don’t ignore it. Consistent BP management matters.”

So, what should happen to your blood pressure when you sleep, and why does this night-time dip matter? Dr Dipak Patil, Consultant Cardiology, KIMS Hospitals, Thane, answers.

Blood pressure normally drops during sleep

“Blood pressure typically drops by about 10 to 20 per cent during sleep compared to its daytime level. This is known as the ‘night-time dip’,” said Dr Patil.

DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.

The reduction happens because the body is less active at night. “The nervous system is less active, and the heart does not have to work so hard,” he explained.

When the reduction is less than 10 per cent, it is generally described as a ‘non-dipping’ pattern. “Although it is not a diagnosis in itself, if it continues, it may indicate that the cardiovascular system is not receiving its normal period of overnight rest,” Dr Patil said.

Can night-time BP be high even when daytime BP is normal?

“Night-time blood pressure is an important element of the full picture of blood pressure,” Dr Patil said. “Even if a person’s readings are normal during the day, they might still have high blood pressure while they are asleep.”

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Consistently elevated night-time BP or a persistent non-dipping pattern has been associated with a higher risk of complications over time, including stroke, heart disease and kidney damage.

“That is one of the reasons why a single daytime blood pressure reading does not give the whole picture,” he said.

If a doctor suspects an abnormal pattern, they may recommend ambulatory blood pressure monitoring, which records BP at regular intervals over 24 hours and can capture readings during sleep.

How does broken sleep affect blood pressure?

“Bad sleep can prevent the usual drop in blood pressure during the night,” Dr Patil said. Frequent awakenings, inadequate sleep and conditions such as obstructive sleep apnoea can keep the sympathetic nervous system active, which may cause BP to remain elevated.

This is why persistent sleep problems should not simply be dismissed as tiredness.

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“Anyone who snores heavily, wakes up choking or gasping, or who feels unusually tired even though they are getting the usual number of hours’ sleep should talk to a doctor,” he advised.

What can help with better BP control?

“Improving the quality of sleep, keeping to a regular sleep schedule, reducing salt intake and adhering to prescribed blood pressure treatment” can all help with better blood pressure control, Dr Patil said.

Ultimately, a normal daytime BP reading is reassuring, but it does not necessarily show what your blood pressure is doing across the entire 24-hour cycle. If there are concerns about night-time BP, disturbed sleep or symptoms suggestive of sleep apnoea, it is worth discussing them with a doctor, he added.

DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.