Is Cortisol useful for Schlaf?

Cortisol follows a circadian rhythm: high in the morning, low at night. Elevated evening cortisol is associated with poor sleep quality and insomnia, but measuring cortisol alone is not a validated tool for diagnosing or managing sleep problems in the general population. While some consumer tests offer cortisol analysis (saliva or blood), the evidence for actionable insights is limited. Studies show correlations but lack interventional proof that adjusting cortisol improves sleep. Evidence: human-moderate for the link, but practice-level weak for routine testing. Caveat: cortisol levels are highly variable; single measurements can be misleading. For persistent sleep issues, consult a healthcare provider for comprehensive evaluation (e.g., sleep study, stress assessment).