Cushing's syndrome is associated with sleep alterations detected by wrist actigraphy

The association between the hypothalamic-pituitary-adrenal (HPA) axis and sleep is well described. It is also known that HPA axis disturbances have an effect on sleep. In fact, patients affected by Cushing's syndrome (CS) often complain about poor sleep quality. Our aim was to evaluate objective sleep quality and duration in patients with Cushing's syndrome in active phase, using wrist actigraphy.

In 12 patients with active CS without ongoing specific therapy (11 F, 1 M; age 40.0 ± 10.9 years; BMI 28.4 ± 6.7 kg/m(2)) and 12 healthy control subjects (HS) (11 F, 1 M; age 44.0 ± 11.0 years; BMI 23.9 ± 4.2 kg/m(2)) an actigraphic evaluation was performed on 3 consecutive days under free living conditions. Objective measurement of sleep duration and quality was estimated by an actiwatch, which is a wristwatch-like device used to detect motor activity.

In CS patients, wrist actigraphy showed higher fragmented sleep (fragmentation index CS 16.2 ± 4.2, HS 13.0 ± 3.6; p = 0.034) and increased nocturnal motor activity (total activity score CS 8318 ± 4308, HS 4971 ± 2372; p = 0.020; mean activity score CS 8.7 ± 4.2, HS 5.4 ± 2.2; p = 0.030; mean score in active time CS 104.8 ± 39.2, HS 74.8 ± 23.1; p = 0.030). On the contrary, actual sleep time resulted similar in CS and HS. No correlation was found between sleep alterations and urinary free cortisol in patients.

The impaired actigraphic parameters described in our study suggest that hypercortisolism is associated with sleep alterations, which could contribute to the worsening of life quality and metabolic comorbidities associated with CS. These results have to be confirmed in a larger cohort of patients, using more accurate instruments for sleep assessment.