To investigate the effects exerted by sleep loss on specific attentive components the performance to a simple reaction time task and to a cued reaction time task were recorded at regular intervals during days following either 8 or 3 h of uninterrupted sleep. Eleven subjects took part in the experiment. The results show that, notwithstanding a general reduction of alertness produced by sleep curtailment (as indicated by the increase of reaction times in the simple reaction time task), in the cued reaction time task only the reaction times to invalidly cued targets significantly increase, while no difference is observed when attention is summoned by a valid cue. This result suggests that the mechanisms underlying orienting of attention are differentially affected by the reduction of alertness level.
