Stress & Cortisol Load Estimator
Estimates your cumulative daily cortisol load and stress burden using validated psychometric and physiological proxies. Outputs a Cortisol Load Index (CLI) and risk tier.
Formula
Cortisol Load Index (CLI) — weighted composite (0–10):
CLI = 0.15·S_sleep + 0.10·S_sleepQ + 0.10·S_exercise + 0.25·S_PSS
+ 0.07·S_caffeine + 0.08·S_alcohol + 0.10·S_work
+ 0.08·S_social + 0.05·S_BMI + 0.02·S_age
Component scores (each 0–10, higher = more cortisol load):
S_sleep = min(10, 2.5·(sleep_h − 8)² / 4) [quadratic penalty from 8 h optimum]
S_sleepQ = 10 − sleepQuality [inverted 1–10 scale]
S_exercise = piecewise: 10→4 (0–2.5 h), 4→0 (2.5–7 h), 0→6 (7–20 h overtraining)
S_PSS = PSS_score / 40 × 10 [PSS-10, 0–40]
S_caffeine = min(10, caffeine_mg / 100)
S_alcohol = min(10, weekly_units / 5)
S_work = min(10, max(0, (work_h − 6) / 12 × 10))
S_social = 10 − socialSupport [inverted]
S_BMI = min(10, |BMI − 22| / 2.8)
S_age = max(0, min(4, (age − 30) / 60 × 4))
Estimated AUC (nmol·h/L) = 100 + CLI × 15
Assumptions & References
- PSS-10 (Cohen et al., 1983) is the strongest validated self-report predictor of HPA-axis activity (r ≈ 0.40–0.55 with salivary cortisol AUC); hence weight = 0.25.
- Sleep: <6 h/night raises morning cortisol by ~37% (Leproult et al., 1997, Sleep). Optimal window 7–9 h (NSF guidelines).
- Exercise: 150 min/week moderate exercise reduces cortisol reactivity; >10 h/week overtraining raises resting cortisol (Skoluda et al., 2012, Psychoneuroendocrinology).
- Caffeine: 250–600 mg raises cortisol ~30% acutely (Lovallo et al., 2005, Psychosomatic Medicine).
- Alcohol: Chronic use (>14 units/week) dysregulates HPA axis (Adinoff et al., 2005, Alcohol Clin Exp Res).
- Social support: High social support buffers cortisol reactivity (Heinrichs et al., 2003, Biological Psychiatry).
- BMI: Central adiposity increases cortisol production via 11β-HSD1 upregulation (Walker, 2006, Best Pract Res Clin Endocrinol Metab).
- Diurnal AUC baseline: 100–150 nmol·h/L (Pruessner et al., 2003, Psychoneuroendocrinology).
- CLI is a screening index, not a clinical measurement. Salivary/urinary cortisol assays are required for diagnosis.