Femto cell networks are becoming very popular in indoor home and small business environments. Femto cells will introduce more interference since all of them work on same frequency band. This limits the capacity of femto cell users. Femto cells may also introduce interference to macro cell users, this again reduces the capacity of Macro cell users. The interference has to be mitigated to improve the capacity of the users. In this work, Sleep mode activation based algorithm is proposed to mitigate the effect of co-tier and cross-tier interference. The simulation results prove that the proposed algorithm improves the Signal to Interference plus Noise Ratio (SINR) when compared no sleep mode based algorithms. © 2015 IEEE.