A method performed by a network node for managing transmission of one or more CRS subframes. The network node identifies if a cell is actively serving a set of UEs. When the cell is actively serving a set of UEs, which set of UEs is configured for DRX the network node sends CRS over the first bandwidth in one or more CRS subframes which are transmitted in the cell during an onDuration interval of the DRX pattern and/or in one or more CRS subframes where system information is sent and/or in one or more CRS subframes where downlink, DL, data is sent. The network node sends CRS over a second bandwidth, in CRS subframes which are not transmitted in the cell during the onDuration interval of the DRX and/or in the one or more CRS subframes except CRS subframes where system information is sent and/or in the one or more CRS subframes except CRS subframes where DL data is sent, which second bandwidth is reduced in relation to the first bandwidth.