Patients with multiple sclerosis (MS) often report fatigue, poor sleep and complaint of sleep disorders. Neurofilament light chain (NF-L) has been identified as a potential biomarker for disease progression in MS patients. In this study, we aimed to evaluate sleep characteristics in MS patients and its relationship with the level of serum NF-L. In the present study carried out as a prospective and cross-sectional study, 32 relapsing-remitting MS (RRMS) patients and 32 control subjects were included. Epworth Sleepiness Scale and Fatigue Severity Scale tests were applied to the groups and the full night polysomnography was performed. Serum samples were obtained for NF-L analysis. Apnea-hypopnea index (AHI), AHI in rapid eye movement sleep (AHI REM), percentage of NonREM stage 1 (N1) and NonREM stage 3 (N3) values were significantly different in RRMS patients (p < 0.05). There was correlation between AHI and Expanded Disability Status Scale indicating a negative directed moderate relationship (r = - 0.343 p = 0.055). Serum NF-L correlations with sleep efficiency and percentage of NonREM stage 2 (N2) were showed mild significant correlation (r = - 0.342 as - 0.535, p < 0.05). We found that sleep disorders are prevalent in RRMS patients and it has a negative effect on the clinical outcome of disease. In clinical practice, the association of these two diseases should be taken into consideration because sleep disturbances increase the disability of MS disease especially presenting with fatigue.