The　energy　of　sensor　nodes　in　wireless　sensor　networks　(WSNs)　is　limited　and　difficult　to　be　replenished,　therefore　energy　conservation　and　energy　management　play　a　very　important　role　in　prolonging　network　lifetime.　To　improve　energy　efficiency,　a　two-stage　clustering　sleep　scheduling　algorithm　with　particle　swarm　optimization　(TCSS-PSO),　combining　clustering　algorithm　and　sleep　scheduling　algorithm,　is　proposed　in　this　paper.　Different　sleep　scheduling　mechanisms　are　adopted　in　two　stages:　a　centralized　sleep　scheduling　mechanism　and　a　distributed　sleep　scheduling　mechanism.　In　the　centralized　sleep　scheduling　mechanism,　particle　swarm　optimization　(PSO)　is　used　to　balance　network　coverage　and　energy　consumption.　Distributed　sleep　scheduling　mechanism　schedules　the　nodes　according　to　their　neighbors’　information　and　their　remaining　energy,　while　it　provides　an　automatic　wake-up　mechanism　to　ensure　network　coverage　and　effectively　respond　to　changes　in　the　network.　Analysis　and　simulation　results　show　that　our　algorithm　can　make　a　good　balance　between　the　improvement　of　network　energy　consumption　effectiveness　and　the　maintenance　of　network　coverage,　effectively　prolonging　the　network’s　lifetime　in　some　extent.　©　2015　Old　City　Publishing,　Inc.