One of the main concerns in wireless sensor networks is improving the network lifetime. The basic idea underlying current studies is the partial utilization of the sensor network resources. Nevertheless, most of the existing works focus on the connection upholding issue, while neglecting the coverage problem. Therefore, we investigate, in this paper, the relationship between the network lifetime and the coverage problem. We show that controlling the density function, relying on efficient sensor nodes placement, can improve significantly network lifetime. In this regard, we propose an efficient placement algorithm addressing the case where the monitored area density is equal to two. Afterwards, we extend the algorithm dealing with the case where the terrain density is higher than two. Finally, we gauge the efficiency of our proposal through analytical models and simulations.