The awakening cortisol response: methodological issues and significance.

Area of Science:

• Endocrinology
• Psychoneuroendocrinology
• Chronobiology

Background:

• The awakening cortisol response (ACR) is a distinct component of the daily cortisol cycle.
• Healthy adults exhibit a 50-160% increase in salivary free cortisol within 30 minutes of waking.
• Established normative ranges for ACR salivary cortisol concentrations are lacking.

Purpose of the Study:

• To review factors contributing to discrepancies in ACR normative data.
• To explore the distinct regulatory mechanisms of the ACR.
• To examine the association between ACR and psychosocial factors, stress, and health outcomes.

Main Methods:

• Literature review of studies investigating the ACR.
• Analysis of confounding factors affecting ACR measurement (e.g., gender, age, awakening time, light exposure, adherence).
• Synthesis of research on the ACR's physiological role and its relationship with psychosocial variables and health.

Main Results:

• Significant variability exists in ACR absolute salivary cortisol concentrations.
• Factors like gender, age, awakening time, light, and adherence influence ACR measurements.
• Studies indicate associations between ACR and psychosocial variables, stress, and health, though the directionality is unclear.

Conclusions:

• The ACR is a unique physiological response potentially regulated differently from the broader diurnal cortisol cycle.
• Despite measurement challenges, ACR is linked to psychosocial factors, stress, and health.
• Further research is needed to define the ACR's role in mediating the mind-body connection and its impact on physiological functions like immunity.