The aim of the present study was to assess the involvement of the locus coeruleus in the paradoxical sleep rebound following sleep deprivation in the rat. Animals were sleep-deprived for 10 h before, and after, specific N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) lesioning of the noradrenergic-locus coeruleus system. Sleep deprivation was produced using either an instrumental (water tank) or pharmacological (methylamphetamine) method. After lesioning, the rats submitted to the instrumental method showed a significant decrease in the paradoxical and slow-wave sleep rebounds (-54% and -78%, respectively), while animals receiving metamphetamine did not. Our results suggest that the noradrenergic system of the locus coeruleus is a relevant component of the sleep rebound mechanisms. However, the extent of involvement is dependent on the sleep deprivation method used.