• Bipolar Disorder
• Chronotype
• Actigraphy
• Sleep
• Glucocorticoids
• Fibromyalgia
• Rheumatology
• Behçet Disease
• Behçet Syndrome
• Disturbo Bipolare
• Cronotipo
• Actigrafia
• Sonno
• Glucocorticoidi
• Fibromialgia
• Reumatologia
• Behcet
• Malattia di Behçet

BACKGROUND
Compared to the general population, Behçet Syndrome (BS) patients show a higher prevalence of sleep disturbances. However, limited research is available on BS patients’ sleep, with no studies using actigraphy, a non-invasive and objective measure of sleep quality and quantity. Furthermore, previous studies did not consider possible confounding factors like fibromyalgia and glucocorticoid treatment when examining the impact of disease activity on BS patients’ sleep alterations. Of note, both chronotype and sleep regularity have been never investigated in BS patients.

OBJECTIVE
In a cross-sectional study, we explored possible differences in sleep parameters and chronotype between BS patients and retrospectively recruited age-, gender- and BMI-matched healthy controls through actigraphic and self-report measures. Furthermore, we aimed at identifying possible predictors of both sleep misperception and sleep parameters in the patients’ cohort.

METHODS
Participants’ sociodemographic data and sleep parameters were collected. Sleep parameters were evaluated through the Pittsburgh Sleep Quality Index and a 7-day actigraphic continuous monitoring. Sleep misperception was defined as the absolute difference between self-reported sleep parameters (i.e., total sleep time and sleep efficiency) and their corresponding actigraphic measurements. The reduced Morningness-Eveningness Questionnaire and the Mood Spectrum Self-Report were used to investigate chronotype and severity of bipolar symptoms, respectively. A comprehensive clinical evaluation of BS patients investigated disease activity, fibromyalgia, and glucocorticoid treatment. Possible predictors of the BS group were explored through binomial logistic models. Within the BS group, possible predictors of sleep misperception and sleep parameters were tested estimating multiple linear regression models.

RESULTS
42 BS patients and 153 controls were included in the study. Compared to healthy controls, BS patients showed worse perceived sleep quality despite no differences in actigraphic parameters and chronotype. Within the BS cohort, higher sleep misperception was associated with increased severity of bipolar disorder symptoms and tendency to morningness. Both active and fibromyalgic patients showed lower perceived sleep quality and higher sleep fragmentation. Moreover, fibromyalgia and active disease were also associated with shorter total sleep time and reduced sleep regularity, respectively. In parallel, glucocorticoids users showed improved sleep regularity and less fragmented sleep.

CONCLUSION
Compared to healthy controls, BS patients showed lower perceived sleep quality despite no differences in objective sleep parameters. Both bipolar disorder symptoms and tendency to morningness may account for the aforementioned discrepancy. Moreover, fibromyalgia and disease activity are two major and independent determinants of sleep impairment in BS patients. In parallel, glucocorticoid treatment may improve BS patients’ sleep by limiting disease activity-related sleep disruption.