Chronotypes in an Uruguayan population affected by multiple sclerosis

Introduction Sleep disturbances in Multiple Sclerosis (MS) are common. Disturbances of the sleep–wake cycle have social, working and even therapeutic implications (i.e. regarding the timing at which treatments are delivered). Objectives The aim of our study was to evaluate the morningness–eveningness preferences in a group of MS affected patients and compare this results with the chronotypes of a control group free from neurological diseases. Materials and methods Fifteen patients from the outpatients MS clinic were included, 12 women and 3 men, with median age 47 [32–67] years. The control group included 8 individuals, 6 women and 2 men, with median age 46 [30–56] years. Both groups were paired by age and sex. A validated Spanish translation of the Horne-Ostberg Morningness–Eveningness Questionnaire (MEQ) was used to study chronotypes. Percentages between groups were compared by the Fisher Exact test and scores by the Mann–Whitney test. Results In the studied population, MEQ test total score showed a median of 56 points in controls [50–66], belonging to the neither chronotype, and a median of 64 in patients [36–75], classified as moderately morning chronotype. Individualized classifications analysis showed: 1.Patients: a. Definitely Evening Chronotype (EEC): 0 patient (0%); b. Moderately Evening Chronotype (MEC): 2 patients (13%); c. Neither Chronotype (IC): 3 patients (20%); d. Moderately Morning Chronotype (MMC): 5 patients (33%); e. Definitely Morning Chronotype (EMC): 5 patients (34%). 2.Controls: a. DEC: 0 (0%); b. MEC: 0 (0%); c. N:7 (88%); d. MMC: 1 (12%); e. DMC: 0 (0%). MMC and DMC were more frequently observed in MS patients (67 % vs. 12 % in controls; ( p  = 0.019). Controls showed higher proportion of NC ( 88% vs. 20% in MS patients; p  = 0,003). Conclusion (1) Chronotypes in the analyzed MS population tend to be morning types. (2)They differ from control population, which presents a non preferential (neither) circadian trend. (3) There appears also a tendency in MS towards a moderately evening preference, although not statistically significant, probably due to the small number of cases and controls studied. (4) Differences should be confirmed studying a larger population. Acknowledgements Hospital de Clinicas - Instituto de Neurologia.