Bangladesh is a good repository of medicinal plants. Traditional healers utilize them for treating many pathological states. Unfortunately, very few of them have been scientifically evaluated to know about the deep inside. The current study here is designed to evaluate the in vivo sedative activity of the leaves of Glochidion multiloculare (Rottler ex Willd) Voigt. With this purpose, the plant leaves were collected and powdered for extraction with methanol. Initially, the plant extract was subjected to brine shrimp lethality bioassay to monitor the presence of bioactive molecules. Later on, different neuropharmacological studies including hole cross, open field, thiopental-sodium induced sleeping time and Elevated-Plus Maze (EPM) tests were conducted to investigate sedative action. In the brine shrimp lethality bioassay, the LC50 value of the extract was found 37.19 μg mL(-1), whereas the standard vincristine sulphate showed the LC50 10.50 μg mL(-1). The moderate toxicity of the extract on brine shrimp indicated the existence of bioactive secondary metabolites in this extract. Besides, the extract decreased the locomotor activity of mice in hole cross, open field and EPM test indicating the CNS depression capability of the plant. Moreover, the extract was very much effective for prolonging the sleeping time (103 min) with quick onset of action (22 min) in comparison to the control group. The efficacy of the plant extract was found closer to the common sedative drug diazepam. Further investigations are required to explore the underlying mechanism of the sedative action and isolate bioactive principles.