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★★★Well replicated — this finding’s sources average out to meta-analyses, systematic reviews or high-powered trials.
People whose cortisol barely fell died of heart disease far more often
Among 4,047 UK civil servants followed about six years, those whose fall was flattest died of heart disease 87% more often, and of any cause 30% more often.
What the study found
The flattest daily curves came with 87% more heart deaths
Cortisol, the body's main stress hormone, normally peaks within an hour of waking and falls away by night. Among 4,047 UK civil servants followed for about six years, those whose fall was flattest died of heart disease 87% more often, and of any cause 30% more often.
The caveat · Just 32 heart deaths behind it
This only tracks a pattern over time, so it cannot show cause. Just 32 of the deaths were from heart disease, which makes the estimate rough. Cortisol was measured on one ordinary weekday. Morning cortisol on its own showed no link at all.