Sleep deprivation induced by the platform technique is considered to be a heavy stressful situation in rats. At the end of the sleep deprivation period (72 h) the rats displayed particular behaviour characterized by wakefulness, a high degree of motor and exploratory activity, increased alertness and reactivity to environmental stimuli. Our previous results indicated that this behaviour was potently antagonized by the administration of the D1-selective antagonist SCH 23390. In this paper we show that concomitantly to this behaviour, an increased number of D1 receptors associated with an increased dopamine-stimulated adenylate cyclase activity is present in the limbic system but not in the striatum of these animals. These data suggest an active role of limbic D1 receptors in the generation of arousal and insomnia related to sleep deprivation induced stress.