Sleepiness and the reinforcing and subjective effects of methylphenidate.

Abstract

On 4 days, 6 volunteers received 10 mg methylphenidate or placebo at 0900 after 4 or 8 hr time in bed (TIB) and then on 4 days after 4 or 8 hr TIB chose their preferred capsule. On sampling days, 4 hr TIB increased multiple sleep latency test (MSLT) scores and Fatigue scale scores on the Profile of Mood States (POMS). In both TIBs, the drug increased the MSLT and POMS Vigor and Tension scale scores. It reduced POMS Fatigue scores and improved divided attention performance to a greater extent after 4 versus 8 hr. Drug was chosen on 88% of days after 4 hr, but only 29% of days after 8 hr. Preference for the drug depends on sleepiness and is mediated by performance-enhancing and fatigue-altering effects.