Subject & Cohort Parameters
Habitual Sleep (Baseline)
5.5 hrs/night
Target Sleep Intervention
7.5 hrs/night
Age Cohort Calibration
Baseline Hazard Ratio
1.24
+24% excess risk
Target Hazard Ratio
1.00
Optimal Nadir Range
Relative Risk Reduction
-19.4%
Delta to 7.5 hrs
Long-Sleep Attenuation
42.0%
Reverse causation drop
Weekly Sleep Extension Simulator
Simulate shifting baseline toward optimal 7.5h nadir via structured increments:
Current debt reconciliation: 14.0 hrs/week of reclaimed sleep deficit.
Adjusted Mortality Hazard Ratio (HR)
Unadjusted (Confounded) Curve
Optimal Nadir Zone (7.0–7.5h)
Bimodal Asymmetry & Etiological Mechanisms
Short Sleep (< 7.0h): Direct Physiological Injury
Causal
Sympathetic hyperactivation, elevated systemic inflammation (CRP/IL-6), endothelial dysfunction, and impaired glucose tolerance drive genuine cardiovascular and metabolic pathology.
Long Sleep (> 9.0h): Reverse Causation
Confounded
Reverse causation driven by subclinical comorbidities, depression, sleep fragmentation, and sedentary baseline. Controlling for occult chronic disease attenuates right-tail hazard by 42%.
Large-Scale Cohort Meta-Analytic Reference Studies
| Cohort / Study | Sample Size (N) | Follow-up | Nadir | Short RR (<6h) | Long RR (>9h) |
|---|---|---|---|---|---|
| UK Biobank Prospective Study | 479,000 | 12.2 yrs | 7.0–7.5h | 1.22 (1.18–1.27) | 1.26 (Adjusted) |
| Nurses' Health Study (NHS I & II) | 184,000 | 24.0 yrs | 7.0h | 1.25 (1.20–1.31) | 1.38 (Unadjusted) |
| Cappuccio et al. Meta-Analysis | 1,382,999 | 15.8 yrs | 7.0–8.0h | 1.24 (1.17–1.31) | 1.30 (1.22–1.40) |