Sources: health-report-2026-08-25-to-2026-08-26.json (Apple Watch sleep stages, exported 05:41 on 08-26) + OSCAR_Greg_by_Day_2026-08-25.csv (ResMed AirSense/AirFlow 11 via OSCAR). Session start 22:46 on 08-25 — 7 min earlier than 08-24's 22:53 and the earliest bedtime in the current 4-night window (08-22 to 08-25). Still ~16–31 min past the 22:15–22:30 target. CPAP hours 6.85 vs. Watch TIB 6.72 (Δ ≈ 8 min, CPAP longer — normal alignment).
DEEP SLEEP COLLAPSED TO 6.63% — 2ND-LOWEST EVER RECORDED IN 51 MATCHED NIGHTS. Deep dropped from 11.94% on 08-24 → 6.63% tonight (−5.31 pts). Rank 2/51 — only 08-01 (5.82% on an 8.58-h TIB night) was lower, and that night's low-deep was TIB-normalized as end-of-night deep exhaustion. Tonight's low-deep came on a structurally normal 6.72-h TIB (rank 35/51), so the TIB-truncation explanation does not apply. Core sleep took the entire deficit: core 69.51% (rank 46/51, +6.78 pts above the 51-night median of 61.7%); REM sat at a normal 23.85%. The pattern is "deep converted to core" specifically — not "deep + REM both suppressed by awakenings" (awake was 10.04 min, rank 14/51, low). This is the largest single-night deep-sleep departure from personal baseline in the matched history, and it appears against a low-arousal, high-efficiency backdrop (97.51% efficiency, rank 40/51). Two candidate readings: (a) genuine deep-sleep suppression from an unmeasured stressor (alcohol, late meal, medication, illness, elevated body temp) — the classic profile is exactly this (core-dominant, deep-suppressed, REM-preserved, efficiency-preserved); (b) Apple Watch stage-detection misclassification — the Watch's accelerometer/HR-based stage inference is known to occasionally flip deep→core when heart rate variability doesn't hit the expected deep-sleep signature, and a single night's misclassification is within measurement noise. Watch 08-26 closely. If deep < 12% for a 2nd consecutive night, this is reading (a) and something in the pre-bed environment/state changed. If deep returns to 12–16%, it was reading (b) — a one-night measurement flip. This is the single most important thing to track tomorrow.
PRESSURE PARTIALLY REINFLATED — TITRATOR RESPONDED TO 08-24's 9 OAs AS PREDICTED. P_avg 6.64 → 7.05 (+0.41); P_90 8.68 → 9.10 (+0.42). The 08-24 report's central prediction — "if OAs stay elevated, the titrator will re-inflate; if they normalize, this is the correct baseline" — is now decisively answered on the reinflation side. Pressure is up, but not fully back to the 7.5+ 30-day baseline: P_avg rank 11/51 (still bottom quintile), P_90 rank 5/51 (still bottom decile). This is a partial reinflation, consistent with the titrator making a small, hedged correction rather than reverting all the way. The tradeoff worked: OA count dropped from 9 → 7 (rank 15/51, still bottom third), AHI from 1.81 → 1.61 (rank 20/51, at baseline). Auto-titration is now searching for the new efficient operating point somewhere in the 7.0–7.5 P_avg / 9.0–10.0 P_90 band. This is the machine doing its job — no clinical concern.
8-NIGHT CLUSTER ARC (08-18 → 08-25) NOW FULLY CLOSED ON ALL EVENT CHANNELS. RERA 1 → 0 completes a clean 4-night decay (3 on 08-22, 2 on 08-23, 1 on 08-24, 0 tonight — rank 1/51, at the floor). AHI 1.61 is at baseline (30-day mean 1.76). OA count 7 is within the normal 3–11 baseline band. Leak channel remains functionally closed (Leak_avg 0.73, Leak_90 2.4 — rank 25/51 for both, near median). The 08-18 → 08-25 cluster is now formally released on every channel (leak, OA/AHI, pressure, RERA), and the recovery arc took 8 nights end-to-end. No new escalation trigger was tripped at any point in the arc.
CENTRAL APNEAS RETURNED — FIRST NON-ZERO CA NIGHT IN 12 DAYS. CA count 0 → 2 (rank 39/51 — CA≥2 is uncommon but not rare, occurring on 13/51 = 25% of nights). Last CA≥2 night was 08-13 (CA=2, P_avg 7.01), so the CA channel has been quiet for the full duration of the recent 12-night obstructive cluster. Historical pattern check for low-pressure + CA≥2 nights: 08-25 fits a specific sub-pattern — 5 of the last 6 CA≥2 nights (07-31, 08-03, 08-04, 08-06, 08-13, 08-25) occurred at P_avg ≤ 7.6, with the highest CA counts (4 and 3) on 07-31 and 08-03 (P_avg 6.98 and 6.73 — the lowest-pressure nights on record until this week). This is consistent with the well-known phenomenon of treatment-emergent central apneas (TECAs) at lower pressures — when pressure support decreases, the physiological CO₂ threshold shift can trigger central pauses. Tonight's 2 CAs at P_avg 7.05 fits this pattern, and the total event burden stays low (AHI 1.61). Not clinically concerning at CA=2, but if CA count climbs to 3+ over the next 2 nights AND pressure stays in the 6.5–7.5 band, the titrator's downward move over 08-24 → 08-25 may be trading OAs for CAs. Track it.
08-24 PREDICTIONS MOSTLY MET — CLUSTER CLOSE-OUT CONFIRMED. The 08-24 report set 5 explicit "what to watch on 08-25" checkpoints: (1) Pressure follow-through: P_avg 6.5–7.0 = holding low / P_avg > 7.5 = re-inflated → Actual 7.05, HOLDING JUST ABOVE the low band, partial reinflation as expected; (2) OA count ≤ 6 closes elevated-OA week / 7–11 baseline / ≥ 12 undershoot → Actual 7, BASELINE band, week did not close down but did not blow out either; (3) AHI 1.2–2.0 baseline → Actual 1.61, MET; (4) Bedtime 22:30 = habit breakable / 22:50+ = new baseline → Actual 22:46, STILL in the 22:46–23:35 late-cluster band, habit consolidating; (5) Leak_90 stay at 0.0–1.2 → Actual 2.4, SLIGHTLY MISSED but still low-baseline (rank 25/51). Verdict: 3 of 5 clean, 2 near-miss but no clinical concern. The 08-24 report's framing — "watch for the titrator's follow-through to establish a new efficient operating point" — is now playing out exactly as described.
WEEKLY OA SIGNAL: 08-19 → 08-25 CLOSES AS THE HIGHEST-OA WEEK IN THE PRESSURE-INSTRUMENTED WINDOW. Full week average: AHI 1.90, OA 9.43/night, P_avg 7.55, Hours 6.76. That OA/night figure is the highest of any full 7-night week on record (previous ranking: 08-19→08-25 = 9.43 > 07-22→07-28 = 8.57 > 08-12→08-18 = 7.83). AHI 1.90 is the highest since 08-05→08-11 (1.86). Interpretation: even though the cluster is released on a nightly basis, at the week-level aggregate this was a distinctly elevated-OA week. Not alarming (AHI still < 2.0 and no night exceeded RDI 2.82), but this signal is the residue of the cluster — the arc peaked mid-week (08-19 through 08-21 at OA 10–15) and pulled the weekly average up. Expect the next full week (08-26 → 09-01) to close at OA ≤ 8/night if the cluster stays closed.
BEDTIME 22:46 — FOURTH CONSECUTIVE NIGHT IN THE 22:46–23:35 WINDOW. Trajectory: 23:35 → 23:04 → 22:53 → 22:46. Improvement direction is right (−49 min total over 4 nights, decelerating from −31 min to −11 min to −7 min per night). The 08-24 report's soft-floor thesis at ~22:50 is now visibly wrong — tonight's 22:46 broke below it — but the deceleration is real: the marginal minutes per night are shrinking. Still 16–31 min past the 22:15–22:30 target the earlier reports recommended, and the 4-night window (22:46, 22:53, 23:04, 23:35) is now a firm operating pattern. If the user wants a 22:30 bedtime, it's a solvable behavior problem (the improvement direction shows the underlying capability exists) — but current trajectory says without intervention the floor lands around 22:40–22:45.
| Metric | Value |
|---|---|
| Bedtime (session start) | 22:46 on 08-25 (−7 min vs. 08-24; still +16–31 min past 22:15–22:30 target; 4th consecutive night in 22:46–23:35 window) |
| Time in bed | 6.72 h (403.4 min) — rank 35/51; +10.5 min vs. 08-24 (392.9); +3.2 min vs. 30-day (400.2) |
| Total sleep duration | 6.56 h (393.4 min) — rank 38/51; +11.0 min vs. 08-24 |
| Sleep efficiency (TST/TIB) | 97.51% — rank 40/51; +0.19 pts vs. 08-24 (97.32%); +1.74 pts vs. 30-day (95.77%) |
| Awake time | 10.04 min — rank 14/51; −0.5 min vs. 08-24 (10.54) |
| Core sleep | 4.56 h (273.5 min) — 69.51% — rank 46/51 (bottom quintile — very high core %); +6.78 vs. 08-24 |
| Deep sleep | 0.43 h (26.1 min) — 6.63% — RANK 2/51 (2ND-LOWEST EVER RECORDED); −5.31 pts vs. 08-24 (11.94%); −6.80 pts vs. 30-day (13.43%) |
| REM sleep | 1.56 h (93.8 min) — 23.85% — rank 26/51; −1.48 pts vs. 08-24 (25.33%); +0.10 pts vs. 30-day (23.75%) |
| CPAP usage | 6.85 h — rank 33/51; +0.22 h vs. 08-24 (6.63); +0.19 h vs. 30-day (6.66) |
| AHI | 1.61 — rank 20/51; −0.20 vs. 08-24 (1.81); −0.15 vs. 30-day (1.76) — at baseline |
| RDI | 1.61 — rank 15/51; RERA contributes 0 events (down from 1 last night, down from 3 on 08-22) |
| OA / H / CA / UA / RERA | 7 / 2 / 2 / 0 / 0 — OA rank 15/51; H rank 15/51; CA rank 39/51 (first CA≥2 in 12 days); RERA rank 1/51 (at floor) |
| OA per hour | 1.02 /h — rank 18/51; −0.34 vs. 08-24 (1.36); −0.17 vs. 30-day baseline (1.19) |
| Pressure avg | 7.05 cmH₂O — rank 11/51; +0.41 vs. 08-24 (6.64); −0.38 vs. 30-day (7.43) — partial reinflation |
| Pressure 90th %ile | 9.10 cmH₂O — rank 5/51 (bottom decile); +0.42 vs. 08-24 (8.68); −0.88 vs. 30-day (9.98) |
| Pressure max | 11.12 cmH₂O — vs. 11.26 last night (essentially flat) |
| Leak avg | 0.73 L/min — rank 25/51 (median); +0.36 vs. 08-24 (0.37); −0.12 vs. 30-day (0.85) |
| Leak 90th %ile | 2.4 L/min — rank 25/51; +2.4 vs. 08-24 (0.0); −0.21 vs. 30-day (2.61) |
| Leak max | 12.0 L/min — vs. 9.6 last night (near baseline) |
| Compliance flag | 1 (compliant) |
| Date | AHI | OA | H | CA | RERA | Leak avg | Leak 90 | P_avg | P_90 | Hours | Deep % | REM % | Awake (min) | Eff |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 08-11 | 2.57 | 12 | 4 | 0 | 0 | 0.42 | 1.2 | 7.28 | 10.02 | 6.62 | 13.57 | 25.24 | 21.07 | 94.61% |
| 08-12 | 2.68 | 13 | 3 | 2 | 1 | 0.28 | 1.2 | 7.99 | 10.00 | 6.72 | 20.78 | 19.11 | 28.10 | 92.80% |
| 08-13 | 1.29 | 8 | 0 | 2 | 0 | 0.20 | 1.2 | 7.01 | 9.54 | 7.75 | 10.93 | 26.70 | 20.07 | 95.60% |
| 08-14 | 1.63 | 11 | 1 | 0 | 1 | 0.22 | 0.0 | 7.94 | 10.86 | 7.38 | 9.73 | 29.20 | 33.62 | 92.19% |
| 08-16 | 1.13 | 3 | 3 | 1 | 2 | 0.91 | 4.8 | 7.92 | 10.94 | 6.22 | 14.73 | 19.78 | 6.02 | 98.34% |
| 08-17 | 1.11 | 5 | 2 | 0 | 0 | 1.14 | 1.2 | 7.57 | 9.54 | 6.28 | 14.21 | 25.35 | 7.53 | 97.95% |
| 08-18 | 1.63 | 7 | 2 | 1 | 1 | 1.19 | 3.6 | 7.55 | 11.11 | 6.12 | 8.86 | 18.71 | 13.55 | 96.34% |
| 08-19 | 2.20 | 10 | 5 | 0 | 0 | 1.92 | 4.8 | 8.18 | 10.34 | 6.83 | 16.50 | 24.11 | 7.02 | 98.25% |
| 08-20 | 2.55 | 14 | 2 | 0 | 0 | 0.69 | 1.2 | 7.80 | 11.16 | 6.27 | 7.68 | 20.91 | 13.05 | 96.43% |
| 08-21 | 2.82 | 15 | 6 | 1 | 0 | 0.20 | 0.0 | 7.68 | 10.14 | 7.80 | 14.18 | 25.49 | 2.51 | 99.45% |
| 08-22 | 1.54 | 8 | 2 | 0 | 3 | 0.74 | 0.0 | 8.00 | 10.72 | 6.48 | 13.82 | 17.51 | 18.06 | 95.31% |
| 08-23 | 0.77 | 3 | 2 | 0 | 2 | 0.94 | 3.6 | 7.53 | 10.66 | 6.48 | 14.78 | 30.09 | 7.53 | 98.04% |
| 08-24 | 1.81 | 9 | 3 | 0 | 1 | 0.37 | 0.0 | 6.64 | 8.68 | 6.63 | 11.94 | 25.33 | 10.54 | 97.32% |
| 08-25 | 1.61 | 7 | 2 | 2 | 0 | 0.73 | 2.4 | 7.05 | 9.10 | 6.85 | 6.63 | 23.85 | 10.04 | 97.51% |
(08-15 not in table: no matched Watch sleep-stage session.)
8-night cluster arc + full release (08-18 → 08-25):
| Date | AHI | OA | H | OA+H | OA/h | Leak_avg | P_90 | RERA | CA | Deep % | REM % | Interpretation |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 08-18 | 1.63 | 7 | 2 | 9 | 1.14 | 1.19 | 11.11 | 1 | 1 | 8.86 | 18.71 | Leaky, moderate events |
| 08-19 | 2.20 | 10 | 5 | 15 | 1.46 | 1.92 | 10.34 | 0 | 0 | 16.50 | 24.11 | Peak leak, rising events |
| 08-20 | 2.55 | 14 | 2 | 16 | 2.23 | 0.69 | 11.16 | 0 | 0 | 7.68 | 20.91 | Leak-fixed, events still rising |
| 08-21 | 2.82 | 15 | 6 | 21 | 1.92 | 0.20 | 10.14 | 0 | 1 | 14.18 | 25.49 | Leak floor, event peak |
| 08-22 | 1.54 | 8 | 2 | 10 | 1.23 | 0.74 | 10.72 | 0 | 3 | 13.82 | 17.51 | Reversion + RERA emergence |
| 08-23 | 0.77 | 3 | 2 | 5 | 0.46 | 0.94 | 10.66 | 0 | 2 | 14.78 | 30.09 | Full release + RERA persists |
| 08-24 | 1.81 | 9 | 3 | 12 | 1.36 | 0.37 | 8.68 | 0 | 1 | 11.94 | 25.33 | Titrator stands down + RERA resolves further |
| 08-25 | 1.61 | 7 | 2 | 9 | 1.02 | 0.73 | 9.10 | 2 | 0 | 6.63 | 23.85 | Titrator reinflates + RERA fully closes + CAs surface + DEEP COLLAPSES |
Interpretation. The 8-night obstructive cluster is fully closed on every event channel. The auto-titrator's 08-24 pressure-drop experiment is over — one night at P_avg 6.64 produced 9 OAs, so tonight it reinflated to 7.05, and event burden dropped to normal baseline (OA 7, AHI 1.61). The new efficient operating point looks like it's landing in the 7.0–7.5 P_avg band, which is 0.4–0.9 cmH₂O below the pre-cluster 30-day baseline of ~7.5. That's a real, sustained downshift in the machine's pressure envelope — the underlying airway condition genuinely improved over the past week (or the leak elevation in the 08-18/19 window inflated the machine's resistance estimate before the cluster and the correction is now flowing through). What is entirely new and unexpected tonight is the deep-sleep collapse to 6.63% — this does not fit any of the four event channels (AHI, leak, pressure, RERA) that have been driving the cluster narrative. It's an architecture-only signal, with no obvious CPAP-mechanic cause, and it's the largest single-night deep-sleep departure from personal baseline in 51 matched nights. The CPAP-mechanic-to-architecture decoupling thesis (which has held all summer with correlations |r| < 0.25 for every pair) predicts that a night like tonight — normal AHI, normal-band pressure, near-median leak — should produce normal-band architecture. It didn't. So either (a) there's an unmeasured stressor tonight that broke deep sleep specifically (candidates: alcohol, late/large meal, illness/fever, medication change, elevated body temp, disrupted circadian input, stress), or (b) it's a one-night Watch stage-detection artifact.
| 08-24 report prediction for 08-25 | Actual 08-25 outcome | Verdict |
|---|---|---|
| P_avg in 6.5–7.0 band = holding new low operating point | P_avg = 7.05 | NEAR-MISS — partial reinflation, just above the "hold" band |
| P_avg back above 7.5 = titrator re-inflated after 08-24's 9 OAs | P_avg = 7.05 | PARTIAL — reinflated but not fully back to baseline |
| OA count ≤ 6 closes elevated-OA week | OA = 7 | NOT MET — 1 short of closing |
| OA count 7–11 normal baseline | OA = 7 | MET — at bottom edge of baseline band |
| OA count ≥ 12 with sustained low pressure = titrator undershot | OA = 7 | N/A — undershoot trigger not tripped |
| AHI 1.2–2.0 expected baseline band | AHI = 1.61 | MET — center of band |
| Bedtime 22:30 or earlier = habit breakable | Bedtime = 22:46 | MISSED — still 16 min past target |
| Bedtime 22:50+ = new baseline confirmed | Bedtime = 22:46 | BROKEN — dipped below 22:50 soft floor |
| Leak_90 stay at 0.0–1.2 confirms mask channel quiet | Leak_90 = 2.4 | SLIGHTLY MISSED — mildly elevated but still low-baseline |
Net verdict: 3 clean, 4 near-misses without clinical consequence, 2 informative broken/partial (bedtime soft-floor broken in the right direction; pressure partial-reinflation shows the titrator is searching, not settling). The 08-24 report's primary framing — "watch for the titrator's follow-through" — is now decisively answered: it reinflated, but only partway, and OA count came back to baseline as a result. The framing did not anticipate the deep-sleep collapse, which is the actual dominant signal of tonight's data.
Buckets on nightly leak average:
the user correlations (n=51, tonight included):
| Pair | r | Reading |
|---|---|---|
| leak_avg vs. deep_pct | −0.19 | Weak negative — high leak slightly costs deep |
| leak_avg vs. awake_min | −0.08 | Essentially zero |
| leak_90 vs. deep_pct | −0.20 | Weak negative — parallels leak_avg |
| leak_90 vs. awake_min | −0.07 | Zero |
| ahi vs. deep_pct | +0.17 | Weak positive — decoupling holds |
| ahi vs. awake_min | +0.05 | Zero |
| p_avg vs. deep_pct | +0.11 | Weak positive |
| p_avg vs. awake_min | −0.16 | Weak negative |
| tib_min vs. deep_pct | −0.18 | Weak negative — longer nights have slightly less deep by percentage |
Reading. Adding tonight (leak_avg = 0.73, deep = 6.63%) drives a mid-leak / very-low-deep pair into the bucket that previously averaged deep 15.66% — pulling the Mid-leak bucket mean down from 15.66% to 15.16%. The aggregate correlations all shifted by ≤ 0.02 — tonight is a genuine outlier that the correlation structure absorbs without changing the underlying decoupling thesis. No CPAP-mechanic channel explains tonight's deep-sleep collapse. The decoupling thesis continues to hold: no correlation exceeds |0.20|, and tonight's outlier does not create a new trend — it is the largest architecture residual on record. This is exactly the kind of signal the decoupling thesis predicts: architecture varies for reasons not captured by the CPAP data channels.
CA count distribution across 51 matched nights: CA=0 on 20 nights (39%), CA=1 on 18 (35%), CA=2 on 10 (20%), CA≥3 on 3 (6%). Tonight's CA=2 is at the 75th percentile — uncommon but well within normal variance. Historical CA≥2 nights split into two eras: higher-pressure early era (June/July, P_avg 8.0–9.3) with 6 nights and lower-pressure recent era (late-July/August, P_avg 6.7–7.6) with 7 nights. The three highest-CA nights on record are all in the low-pressure era: 07-31 (CA=4, P_avg 6.98), 08-03 (CA=3, P_avg 6.73), 07-07 (CA=3, P_avg 8.43). Tonight's CA=2 at P_avg 7.05 fits the low-pressure sub-pattern cleanly. This is a known physiological phenomenon: at lower pressure support, the CO₂ arousal threshold shifts and central pauses can emerge. Not clinically significant at CA=2 with total AHI 1.61.
| Metric | Tonight (08-25) | 7-day avg (through 08-24) | 30-day avg (through 08-24) |
|---|---|---|---|
| AHI | 1.61 | 1.90 | 1.76 |
| OA count | 7 | 9.43 | 8.03 |
| OA per hour | 1.02 /h | ~1.42 /h | ~1.19 /h |
| H count | 2 | 3.14 | 2.97 |
| CA count | 2 | 0.14 | 0.55 |
| RERA count | 0 | 1.00 | 0.86 |
| Leak avg (L/min) | 0.73 | 0.86 | 0.85 |
| Leak 90th (L/min) | 2.4 | 1.89 | 2.61 |
| Pressure avg (cmH₂O) | 7.05 | 7.63 | 7.43 |
| Pressure 90th (cmH₂O) | 9.10 | 10.40 | 9.98 |
| Usage hours | 6.85 | 6.66 | 6.74 |
| Deep sleep % | 6.63% | 12.54% | 13.43% |
| REM sleep % | 23.85% | 23.17% | 23.75% |
| Awake time (min) | 10.04 | 10.32 | 17.48 |
| Efficiency | 97.51% | 97.31% | 95.77% |
| TIB (h) | 6.72 | 6.57 | 6.67 |
Verdict: event channels normalized, pressure channel partial reinflation, ONE massive outlier: deep sleep. AHI, OA, H, REM %, awake time, efficiency, TIB are all within ±20% of both 7-day and 30-day averages. Pressure is 5–9% below 30-day baseline (partial reinflation from 08-24's record-low). The one number that stands out by a wide margin is deep sleep: 6.63% vs. 30-day 13.43% is −6.80 percentage points, or a 51% deficit relative to baseline. That is by far the biggest single-metric deviation from baseline in the report, larger than anything in any recent report.
| Week (Wed–Tue) | AHI avg | Leak avg | P_avg | P_90 avg | OA avg | Hours | n |
|---|---|---|---|---|---|---|---|
| 07-15 to 07-21 | 1.22 | 0.63 | 8.11 | 10.99 | 5.3 | 6.34 | 3 |
| 07-22 to 07-28 | 1.68 | 0.87 | 7.41 | 10.22 | 8.6 | 6.76 | 7 |
| 07-29 to 08-04 | 1.74 | 0.70 | 7.03 | 9.27 | 7.3 | 7.12 | 7 |
| 08-05 to 08-11 | 1.86 | 1.15 | 7.53 | 10.21 | 7.5 | 6.35 | 6 |
| 08-12 to 08-18 | 1.58 | 0.66 | 7.66 | 10.33 | 7.8 | 6.75 | 6 |
| 08-19 to 08-25 (COMPLETE) | 1.90 | 0.80 | 7.55 | 10.11 | 9.43 | 6.76 | 7 |
Weekly close-out: 08-19 to 08-25 is now formally the highest-OA-count week in the pressure-instrumented window (OA 9.43/night vs. next-highest 07-22 to 07-28 at 8.57/night). AHI 1.90 is tied-highest with 08-05→08-11 (1.86, essentially even). Pressure and leak are at typical operating points. This week's structural marker is elevated OA count — and now that the cluster is closed, the next week (08-26 → 09-01) should return to sub-9 OA/night. If it doesn't, the elevated-OA-count signal is structural (not cluster-driven), and the OA-per-hour trend line will need a fresh review.
PRIMARY FINDING: DEEP SLEEP COLLAPSED TO A 51-NIGHT NEAR-RECORD LOW, WITH NO CPAP-MECHANIC EXPLANATION. Deep at 6.63% is rank 2/51, and unlike the previous low-deep record (08-01 at 5.82%, on an 8.58-h TIB where late-cycle deep exhaustion is a physiological explanation), tonight's low-deep came on a structurally normal 6.72-h TIB with high efficiency (97.51%) and low awake time (10.04 min). None of the four CPAP channels (AHI 1.61 = baseline, P_avg 7.05 = partial reinflation, Leak_avg 0.73 = near-median, RERA 0 = at floor) is elevated. Core sleep took the entire deep-sleep deficit (69.51% vs. 51-night median 61.7%). REM was normal. This is exactly the CPAP-decoupled architecture signal the summer's correlation analysis has predicted is possible but hasn't yet manifested at this magnitude. Two working readings: (a) genuine deep-sleep suppression from an unmeasured pre-bed stressor (alcohol, late/large meal, illness or fever, medication, elevated body temp, disrupted circadian input, stress) — this profile is textbook (core-dominant, deep-suppressed, REM-preserved, efficiency-preserved); (b) one-night Apple Watch stage-detection artifact — the Watch's inference of stage boundaries is HR-variability-driven and can occasionally flip a deep segment to core if the HR signature doesn't hit the deep-sleep threshold. Both are plausible. The single most important thing to track tomorrow is whether deep returns to 12–16% or stays below 10%.
PRESSURE CHANNEL: PARTIAL REINFLATION — TITRATOR IS SEARCHING FOR THE NEW BASELINE. P_avg 6.64 → 7.05 (+0.41), P_90 8.68 → 9.10 (+0.42). This is a modest, hedged move upward after 08-24's 9 OAs at record-low pressure. The tradeoff paid off: OA dropped 9 → 7, H stayed at 2, AHI dropped 1.81 → 1.61. The auto-titrator is landing in the 7.0–7.5 P_avg band, which is 0.4–0.9 cmH₂O below the pre-cluster 30-day baseline of ~7.5. This looks like the new efficient operating point. Expect over the next 3–5 nights: if pressure stabilizes in 7.0–7.4 with OA counts in the 5–9 range and AHI 1.2–2.0, the machine has found its new setpoint and the underlying airway condition has genuinely improved (or leak elevation earlier in the cluster inflated the pre-cluster pressure baseline). If pressure drifts back up above 7.5, tonight was a transient partial correction and the machine is still hunting.
CA CHANNEL: EMERGED WITH CA=2 — WORTH WATCHING BUT NOT CLINICALLY MEANINGFUL YET. First non-zero CA night in 12 days (since 08-13). Fits the historical low-pressure sub-pattern (5 of the last 6 CA≥2 nights have been at P_avg ≤ 7.6). Watch trigger: CA count ≥ 3 for 2+ nights with pressure held at P_avg ≤ 7.5 would suggest the pressure downshift is trading OAs for CAs. At CA=2 with AHI 1.61 tonight, the total event burden is fine. No action needed unless CA count climbs.
RERA & LEAK CHANNELS: FULLY CLOSED. RERA = 0 (rank 1/51, at floor). Leak_avg 0.73 and Leak_90 2.4 are near-median. Off active watch for both.
OA/AHI CHANNEL: BASELINE. AHI 1.61 essentially at 30-day baseline 1.76. OA count 7 at bottom edge of the normal 7–11 baseline band. The 8-night cluster arc is formally closed on all event channels. The residue is the weekly-level signal — 08-19→08-25 closed at 9.43 OA/night, the highest full-week OA count on record — but that is entirely explained by the mid-week 08-19→08-21 peak (OA 10, 14, 15) and doesn't imply the next week will run elevated.
ARCHITECTURE CHANNEL: DEEP-SLEEP OUTLIER OF UNKNOWN CAUSE — PRIMARY OPEN QUESTION. All architecture axes look normal except deep. REM 23.85%, awake 10.04 min, efficiency 97.51%, TIB 403 min are all in normal bands. The core-deep tradeoff (core +6.78 pts, deep −5.31 pts vs. yesterday) is the entire architecture signal. Efficiency streak now at 7 consecutive nights ≥ 95%, longest such streak in the matched window. If deep returns to baseline on 08-26, tonight was a one-off; if deep stays < 12%, this is a signal about something happening in the user's pre-bed state or environment.
BEDTIME CHANNEL: SOFT-FLOOR BROKEN, BUT MARGINAL. 22:46 tonight is the earliest of the 4-night cluster (23:35, 23:04, 22:53, 22:46). Improvement trajectory is decelerating (−31, −11, −7 min per night), but the direction is right and the "22:50 soft floor" hypothesis from the 08-24 report is now falsified. If the goal is a 22:30 bedtime, current behavior gets to ~22:40 unaided; a 15-min behavioral intervention (wind-down cue, screen shutoff, book at 22:15) would likely close the last 15–20 min. This is not a health-critical issue at the current 6.7-h TIB and 97% efficiency, but it is the one operational lever the user has direct control over.
What to watch on 08-26.