Hidden Hypertension Spikes While Patients Sleep

Woman sleeping with a black eye mask in bed — Photo: PH888 / Shutterstock

A hormone disorder tied to millions of high blood pressure cases can hide from a routine blood test simply because it strikes hardest while patients are asleep.

Quick Take

A new study used a waist-worn wearable to track hormone levels every 20 minutes for 24 hours in 60 patients.
The device caught nighttime surges of aldosterone, a hormone that raises blood pressure, that standard clinic blood draws missed.
Researchers say the condition, called primary aldosteronism, may already be badly underdiagnosed in people with high blood pressure.
The technology could eventually change how doctors screen for hidden hormone-driven hypertension.

A Device That Watches Hormones All Night Long

Scientists from the University of Bristol, the University of Manchester, the University of Bergen, and research partners in Stockholm and Athens built a small sensor worn at the waist. It drew fluid from just beneath the skin every 20 minutes, without needles, tracking hormone activity around the clock. Sixty patients wore it while living normally, including through a full night of sleep.

The results, published in Science Translational Medicine, showed something a single clinic visit could never catch. Patients with primary aldosteronism had bursts of hormone production during the day, but the biggest spikes happened at night while they slept. A standard blood draw, taken during business hours, would likely miss those surges entirely.

Why A Single Blood Test Falls Short

Primary aldosteronism happens when the adrenal glands pump out too much aldosterone, a hormone that tells the body to hold onto salt and water. That extra fluid drives blood pressure up. Doctors normally diagnose it using a blood test called the aldosterone-to-renin ratio, taken at one point in time in a clinic. If a patient’s hormone levels happen to be calm at that exact moment, the test can come back looking normal even though the disease is active.

The condition is already known to be far more common than most patients realize. Medical reviews have called it “woefully underdiagnosed,” and one widely cited estimate found that only about 1 in 550 Americans with the disorder ever gets properly diagnosed and treated. A Mayo Clinic review reached a similar conclusion, describing primary aldosteronism as a prevalent but frequently missed cause of high blood pressure that raises the risk of heart and blood vessel damage over time.

Not Everyone Agrees Wider Screening Solves The Problem

Not every expert treats “underdiagnosis” as a simple fix-it problem. An older review of the field pushed back on the idea that more sensitive tests automatically mean doctors are catching more real disease. It found that while better screening tools do turn up more positive results, that does not prove more patients actually have the surgically fixable form of the condition. That is a fair point worth keeping in mind as wearable technology promises to find even more hidden cases.

Still, the gap between how common the disease may be and how rarely it gets caught has stayed wide for years. One review from Germany found that roughly 2.5 million people there may have the condition, yet only about 8 percent of hypertensive patients ever get the recommended screening. Updated 2025 guidance from the Endocrine Society pushed for broader testing, but doctors on the ground still report the same old bottleneck: patients rarely get tested unless a physician specifically suspects the disorder.

What This Could Mean For Patients And Doctors

If wearable hormone monitors move from research labs into everyday clinics, they could change how doctors approach stubborn, hard-to-control high blood pressure. Instead of relying on one blood draw that might land at the wrong moment, a device could track a patient’s hormone rhythm over a full day and night. That kind of continuous picture matches how the disease actually behaves, not how a clinic schedule happens to catch it.

For the roughly 116 million American adults living with high blood pressure, a missed diagnosis is not a small inconvenience. Primary aldosteronism, when caught, is often treatable with targeted medication or even surgery, potentially curing the high blood pressure rather than just managing it for life. Better tools for catching a condition doctors already suspect is common could mean fewer people spending decades on blood pressure pills that never address the actual cause.