Sleep problems are commonly seen in children with Autism Spectrum Disorder (ASD). According to previous research, sensory problems and anxiety may be related to the development and maintenance of sleep problems in children with ASD. To determine pattern and severity sleep disturbance in children with autism spectrum disorder. This descriptive cross sectional study was done in Institute of Paediatric Neuro-disorder and Autism (IPNA) and Department of Paediatric Neurology, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh from October 2017 to September 2018. A total of 59 children aged 3 to 15 year who were diagnosed as ASD according to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) were enrolled in this study. Sleep disturbances were recorded in the standard questionnaire. The mean age was 49.78±20.69 months and male to female ratio was almost 4:1. More than two third (69.2%) patients had sleep awakening in mild, 7(36.8%) in moderate autism spectrum disorder. The difference was statistically significant (p<0.05) among three groups. More than half (56.4%) patients had sleep starting 12 am to 2 am in mild, 3(15.8%) in moderate autism spectrum disorder. The difference was statistically significant (p<0.05) among three groups. Sleep awakening and sleep starting time were significantly associated with autism spectrum disorder.