||Human behavioural responses have an important impact on the spread of epidemics. To deal with them, some epidemic models consider that individuals are aware of the risk of contagion and adopt preventive responses when they learn about the existence of the disease. If awareness is assumed to be transmitted from individual to individual, the information dissemination can be thought to spread over a second network where links are defined according to a certain type social relationship (friends, acquaintances, etc. ), with the same set of nodes as the contact network. Here we present a simple model for epidemic spreading with awareness defined on a two-layer network which includes the overlap between these two layers as a parameter. This formulation leads to an expression of the epidemic threshold as a function of the network overlap.