The Overnight Clue Standard Testing Keeps Missing

Key takeaways

• A new wearable device tracked hormone levels every 20 minutes over a full 24-hour cycle and revealed hidden bursts of adrenal hormone activity happening specifically at night.
• These nighttime bursts can dip below typical detection thresholds at other times of day, meaning a single blood draw taken at the wrong moment can miss the pattern entirely.
• When the hormone-producing tissue behind the bursts was surgically addressed, the unusual nighttime pattern disappeared, reinforcing that it was a real, measurable rhythm rather than noise.
• The bigger picture: some blood pressure–related hormone patterns may only become visible when you look at rhythm across a full day and night, not a single snapshot.

A blind spot in a single blood draw

Most hormone testing works the way you'd expect: a blood draw at a clinic, at one point in time, gives one data point. That approach works well for hormones that stay fairly stable, but it runs into trouble with hormones that naturally rise and fall throughout the day, and especially overnight while most people are asleep and nowhere near a clinic.

Researchers from the University of Bristol, the University of Manchester, the University of Bergen, and collaborators in Stockholm and Athens set out to see what a full 24-hour hormone picture might reveal that a single test could not, particularly for a common adrenal hormone pattern linked to elevated blood pressure.

Tracking hormones around the clock

The team used a lightweight, phone-sized wearable device, developed at Bristol and known as U-RHYTHM, that samples hormones through the skin and attaches at the waist. Sixty participants across four cities wore the device for 24 hours while going about normal life, including sleeping, letting researchers capture hormone activity every 20 minutes without requiring a hospital stay.

The device tracked aldosterone, a hormone involved in the body's salt and water balance, along with two closely related hormones. This continuous approach meant researchers could finally see the full shape of each person's daily hormone rhythm rather than a single point along it.

What the nighttime pattern revealed

The results were striking. Rather than staying steadily elevated, aldosterone showed repeated bursts of activity concentrated at night, while the overall day-night hormone rhythm stayed largely intact. In some cases, hormone levels dipped low enough at certain points that a test taken right then would have looked unremarkable, even though nighttime bursts told a different story.

These bursts were most pronounced in participants whose pattern traced back to one adrenal gland rather than both, and when the affected tissue was surgically addressed, the nighttime bursts disappeared. That before-and-after contrast gave researchers confidence the pattern was a genuine, hormone-driven signal.

A longevity lens: rhythm over snapshots

This research fits a broader shift happening across health monitoring: moving from single snapshots toward continuous, rhythm-aware measurement. Sleep trackers, continuous glucose monitors, and now wearable hormone sensors are all pointing toward the same idea, that a lot of meaningful biology only shows up when you watch it unfold over time instead of checking in once.

For anyone paying attention to their own long-term health, it's a useful mental model: your body's rhythms, not just its momentary readings, may hold some of the most actionable information.

The takeaway

This is proof-of-concept work, and turning it into a routine clinical tool will take more research on the best ways to capture and interpret these patterns. But the core insight travels well beyond this one hormone: for biology that naturally rises and falls, a single test can tell an incomplete story, and around-the-clock monitoring may be the key to catching what a snapshot misses.

References:

Marianne A. Grytaas, Thomas Upton, Isabella Marinelli, Paal Methlie, Marianne Øksnes, Dimitra A. Vassiliadi, Sophie Bensing, Georgina Russell, Kristian Løvås, Dimitris Margaritopoulos, Ileana R. Botusan, Katerina Simunkova, Maria Balomenaki, Katarina Berinder, Belinda Lombard, Thea Sjøgren, Ida Løvik, Bergithe E. Oftedal, Anette Heie, Grethe Å. Ueland, Olle Kämpe, Stylianos Tsagarakis, Stafford L. Lightman, Eder Zavala, Eystein S. Husebye. Tissue corticosteroid rhythms are dysregulated predominantly during sleep in primary aldosteronism. Science Translational Medicine, 2026; 18 (864) DOI: 10.1126/scitranslmed.aeb7517