An apparatus and method for controlling an air current in a sleep mode of an air conditioner, in which the directions of air discharged through discharge holes and the volume of the discharged air are controlled so as to reduce power consumption while creating a comfortable sleeping environment. The method for controlling an air current in a sleep mode of an air conditioner having blades for adjusting directions of discharged air, includes determining whether the sleep mode is inputted; sensing an indoor temperature, when it is determined that the sleep mode is inputted; and comparing the sensed indoor temperature with a set control temperature, and adjusting the directions of the discharged air according to the results of the comparison.