# Cortisol (serum/salivary)

Cortisol is the main glucocorticoid (stress hormone) from your adrenal glands. It is the final output of the HPA axis, the loop linking your hypothalamus, pituitary, and adrenals. It runs on a strong daily rhythm. Levels jump 50 to 160% within 30 to 45 minutes of waking, the 'cortisol awakening response' (CAR). Then they fall to a low point by late evening. You measure it with morning blood or a series of saliva samples. The CAR is caught at wake-up, +15 min, and +30 min. A constantly overactive HPA axis (high evening cortisol, a flat daily slope, or a blunted CAR) eats into muscle. It does so by quieting IGF-1 signals and ramping up protein breakdown, which speeds the muscle loss of sarcopenia. Lower overall daily output goes with longevity. In the Leiden Longevity Study (Noordam 2012), children of very long-lived siblings had clearly lower daily saliva cortisol than matched controls, regardless of health habits. A scoping review by Palmese et al. (2025, European Geriatric Medicine) found that a steeper daily drop tracked with faster walking, better chair-rise time, and lower frailty risk. But the authors call the evidence patchy and too thin to prove cause. The cognitive link is also just an association. In the Whitehall II and NSHD cohorts (Tsui 2020, Neurology), a higher morning-to-evening ratio in mid-life predicted better later cognition, while a flat pattern predicted worse.

## Sources

- Noordam R, Jansen SW, Akintola AA, Oei NY, Maier AB, Pijl H, et al.. (2012). Familial Longevity Is Marked by Lower Diurnal Salivary Cortisol Levels: The Leiden Longevity Study. PLoS ONE. https://doi.org/10.1371/journal.pone.0031166
- Tsui A, Richards M, Singh-Manoux A, Udeh-Momoh C, Davis D. (2020). Longitudinal associations between diurnal cortisol variation and later-life cognitive impairment. Neurology. https://doi.org/10.1212/WNL.0000000000008729
- Palmese F, Druda Y, Del Toro R, Bedogni G, Domenicali M, Silvani A. (2025). The role of the circadian timing system in sarcopenia in old age: a scoping review. European Geriatric Medicine. https://doi.org/10.1007/s41999-024-01129-0

---

_Canonical: https://longevity-switzerland.com/en/glossary/cortisol · Part of Longevity Cities · Updated 2026-06-22_