Effects of modafinil on attentional processes during 60 hours of sleep deprivation

The present study investigates the effects of modafinil (300 mg/24 h) versus a placebo on the performance of a visual search task during 60 h of sleep deprivation. Modafinil was administrated in doses of 100 mg three times per day during sleep deprivation. Six healthy volunteers participated in a double-blind experiment including two experimental sessions of 7 days each. The experiment used the visual search paradigm for an 'O' target among 'Q' distracters and the reverse. The speed and accuracy in detecting the target were measured by RTs slopes (i.e. search rates) and the number of errors (i.e. error rates), respectively. Many authors attribute rapid search rates obtained for 'Q' targets (low RTs slopes) to parallel/automatic processes and slow search rates obtained for 'O' targets (high RTs slope) to serial/attentional processes. The results revealed an asymmetrical search pattern for the detection of 'Q' versus 'O' targets across the sleep deprivation period (i.e. parallel versus serial search, respectively). Rapid search rates for 'Q' targets remained unchanged between placebo and modafinil conditions during sleep deprivation. However, slow search rates for 'O' targets increased linearly in placebo condition, but remained at the same level as the control-test in modafinil condition. Error rates and search rates also increased. For 'O' and 'Q' targets, the number of errors increased in the placebo condition, but remained stable in the modafinil condition. In summary, we can conclude that the administration of modafinil (300 mg/24 h) during sleep deprivation prevents the slowing of serial processes (attentional shifts) and the increasing of errors. (C) 1998 John Wiley & Sons, Ltd.