Endocrine Abstracts

Introduction: Patients with Cushing’s Syndrome (CS) frequently have sleep complaints. The aim of the study was to evaluate the prevalance sleep disturbances and sleep structure of patients with CS.

Materials and methods: 33 patients with CS were evaluated both clinically and with polysomnograhy (PSG) findings in terms of sleep disorders and data were compared with 20 healthy controls.

Results: Seventeen (51.1%) patients with CS demonstrated sleep apnea (Apnea Hypopnea Index (AHI)≥5), with seven (21%) of 17 had severe sleep apnea (AHI≥30). Five (15%) patients had periodic limb movements (PLM) of sleep (PLM Index ≥15), 20 (60%) patients had clinical insomnia, and two (6.1%) patients had restless legs syndrome. None of the CS patients complained of hypersomnia (Epworth sleepiness scale ≥10). PSG parameters were compared only if participants had an AHI<5 and PLMI<15. The percentage of stage N2 sleep was significantly increased in CS patients (65.3±11.4%) compared to control subjects (54.4±13.3%). Although total sleep time (297.9±104.0 min in CS, vs 354.8±52.8 min in controls) and percentage of time spent in stage N3 sleep (12.9±1.9% in CS, vs 23.3±16.2% in controls) was reduced in CS patients, the difference was not statistically significant. Average heart rate (73.7±6.9/min in CS, vs 65.6±7.5/min in controls) and minimum heart rates (58.8±6.1/min in CS, vs 51.8±7.6/min in controls) were significantly higher in CS patients. There was a significant positive correlation between post-dexamethasone cortisol levels and AHI, and midnight cortisol levels and AHI in REM sleep. Minimum O₂ saturation was found to be negatively correlated with midnight cortisol and basal cortisol levels.

Conclusion: Insomnia and sleep apnea are frequent sleep disorders in CS patients. Absence of hypersomnia, alterations in sleep structure and higher heart rate during sleep support a hyperarousal state in CS. These alterations may potentially influence metabolic comorbidities associated with CS.