Conventional layered network architecture schemes partition sensor nodes into layers based on their distances (i.e., hop-count) from the sink, forwarding gathered data through those nodes with few hop-counts to reduce the energy consumption of a node. Nevertheless, a node that connects with too many nodes in its neighbor layer still incurs significant amount of data forwarding. This node generally exhausts its power supply rapidly, ultimately reducing network lifetime. This work proposes an energy efficient time-slot allocation (EETA) scheme based on the number of neighbor nodes to reduce node energy consumption and prolong network lifetime in a multi-hop layered WSN. Simulation results demonstrate that the proposed EETA scheme can prolong network lifetime more than conventional multi-hop layered network architecture schemes.