Cluster based Wireless Sensor Networks (WSNs) have been widely used for better performance in terms of energy efficiency. Efficient use of energy is challenging task of designing these protocols. Energy holedare created due to quickly drain the energy of a few nodes due to non-uniform distribution in the network. Normally, energy holes make the data routing failure when nodes transmit data back to the base station. The authors proposed Energy-efficient HOle Removing Mechanism (E-HORM) technique to remove energy holes. In this technique, they use sleep and awake mechanism for sensor nodes to save energy.