The longitudinal association of sleep and 24-hour activity rhythms with cortisol response to a very low dose of dexamethasone

Abstract

ObjectivesPoor sleep is common in the general population, with hyperarousal and stress often suggested as causal factors. Conversely, sleep might also affect the stress response, in which the hypothalamic-pituitary-adrenal (HPA) axis plays a key role. We assessed the longitudinal association of sleep and 24-hour activity rhythms with functioning of the negative feedback loop of the HPA axis, as indicated by the cortisol response to a very low dose of dexamethasone. DesignLongitudinal cohort. SettingPopulation-based. ParticipantsThis study included 410 participants (mean age: 56.1 ± 5.5 years, 59% women) from the Rotterdam Study. For 217 participants, the cortisol response to dexamethasone was assessed again after a median follow-up of 5.7 years (IQR = 5.5-5.8). MeasurementsBetween 2004 and 2007, sleep and 24-hour activity rhythms were estimated with actigraphy (mean duration: 146 ± 19.6 hours) and sleep quality with the Pittsburgh Sleep Quality Index. To assess the negative feedback loop of the HPA axis we measured cortisol before and after the intake of a very low-dose of dexamethasone (0.25 mg). ResultsUnstable (B = 1.64, 95% CI = 0.78; 2.50) and fragmented (B = -1.31, 95% CI = -2.17; -0.45) 24-hour activity rhythms, and a poor self-rated sleep quality (B = -0.02, 95% CI = -0.04; 0.00) were associated with an enhanced cortisol response to dexamethasone over time, also in those without clinically relevant depressive symptoms and those not using psychoactive medication. ConclusionsThis study demonstrates a longitudinal association of disturbed 24-hour activity rhythms and poor self-rated sleep quality with an enhanced cortisol response to dexamethasone, in other words stronger suppression of cortisol. Statement of significanceThis study shows that disturbed 24-hour activity rhythms and a poor self-rated sleep quality are associated with functioning of the negative feedback loop over a period of years.