The U-dip

Orthostatic · present A within-day stress dip Wiggers ties to blood volume and treats with electrolytes

What the guide says Brief drops in stress followed by a higher plateau read as an attempted recovery that didn't take.

Do I see it in my own data?

Present?: Yes. This is one of the patterns of hers I can actually see on this watch.
When: More common in my earlier years than my recent ones. But those recent years are also when I started citalopram, so I can't cleanly separate a real easing from the medication era; the timing is suggestive, not a clean trend. And I never took up her salt-and-fluid routine, so the easing can't be credited to that either.
Under what circumstances: She ties it to blood volume and treats it with electrolytes; I never took up that side of her advice, no extra salt, fluids, or electrolytes, so whatever eased over the years, I can't credit it to anything I did about my circulation. I cannot confirm the orthostatic story from my own record either: my notes never logged the standing dizziness or salt cravings that would pin a U-dip to an orthostatic moment. The pattern is on the watch; the story around it is not.

Where this one stands

Wiggers' circulation pattern, which she treats with electrolytes; I never did. Present in my data and time-varying, not a crash predictor. Reading it as a failed crash signal was the wrong question.

This is the pattern Wiggers ties to blood volume and treats with electrolytes, her U-dip. It is present in my data and it comes and goes over time, more common in my earlier years than my recent ones; but those recent years are also when I started citalopram, so I can't cleanly tell a real easing apart from the medication era. And I never took up the extra salt and fluids she recommends, so the easing can't be credited to that. One honest limit: this is not a validated reading of POTS. POTS is defined by a heart-rate jump on standing that this watch has no sensor to see, and the dip itself runs the opposite way to the textbook pattern, so I name it a circulation pattern Wiggers reads as orthostatic, not something the watch diagnosed. It is not a crash signal, and it was never meant to be: I did also check whether it flagged the run-up to a crash, and it did not (about half of crash lead-ups and half of ordinary days, single-pool null), which is exactly what you would expect from a circulation pattern that is not about crashes. This is early, descriptive work, and it rests on the watch pattern alone.

The numbers, for the record Single-pool NOT-SUPPORTED. Sensitivity ~58%, specificity ~59%; PPV ~2.9% at the ~2% base rate, lift ~1.39x (Tier C).

The full write-up (what showed up, how it was tested, and what it means) is coming as this finding’s analysis closes. For now, the status and the working note above are the honest summary.