Disturbed sleep, 24-hour activity patterns tied to stronger suppression of cortisol

Cortisol response following a very low dose of dexamethasone appears to be much stronger in people with disturbed 24-hour activity patterns and poor sleep quality, a recent study has found.

“Within our population-based sample of middle-aged and elderly, unstable and fragmented 24-hour activity rhythms at baseline were associated with an enhanced cortisol response to dexamethasone over time, indicating a stronger suppression of cortisol by the negative feedback of the hypothalamic-pituitary-adrenal (HPA) axis,” the researchers said.

The study included 410 participants (mean age 56.1 years, 59 percent women), in whom actigraphy was used to assess sleep and 24-hour activity rhythms. Self-reported sleep quality was rated using the Pittsburgh Sleep Quality Index. Cortisol levels were measured before and after administering very low-dose dexamethasone to assess the negative feedback loop of the HPA axis.

Results showed that those who had unstable 24-hour activity rhythms at baseline demonstrated a significantly stronger cortisol response to dexamethasone over 5.5 years of follow-up (B, 1.64, 95 percent confidence interval [CI], 0.78–2.50).

A similar effect was reported for fragmented 24-hour activity rhythm at baseline (B, –1.31, 95 percent CI, –2.17 to –0.45) and poor self-rated sleep quality (B, –0.02, 95 percent CI, –0.03 to 0.00).

Of note, the principal findings proved to be robust to various sensitivity analyses that excluded nonresponders to dexamethasone, those with clinically significant depressive symptoms, or those who used psychoactive drugs.