Background: Portulaca oleracea (PO) and Melissa officinalis (MO) overgrow in the different parts of Iran. In previous studies, systemic administration of the extract of PO and MO induces antinociceptive, anxiolytic and anticonvulsive, sedative effects in animals. Objective: This study was designed to evaluate different doses of the aqueous decoction extracts of PO and MO on sleeping time on mice. Methods: Male albino mice (25 - 30 g) were used in this study. The animals divided to control (saline), PO (25, 50 and 75 mg/kg) and MO (5, 10 and 25 mg/kg) groups (by IP injection). For measuring of sleeping time we used Angle method. Results: The results have shown that three doses of PO and two doses of 10 and 25 MO significantly increased sleeping time (p=0.000). Conclusion: This finding showed that PO and MO may be play important role on the modulation of sleeping time.