Cocaine use often is part of night time social activities. To examine the drug's effects in combination with time-of-day variables, 24 male Ss were given cocaine and tested between 1830 and 2400. After 8 hrs sleep in the laboratory, Ss were tested the following morning. Treatments were 5 mg (placebo), 96 mg, and 126 mg cocaine taken intranasally in 3 equal amounts at half hr intervals. The first test battery began 25 mins after the third dose and the second battery began 3 hrs later. Day 2 testing began half hr after Ss arose. Although subjectively-experienced stimulation by cocaine is relatively short-lived, divided attention (D-A) and vigilance (VIG) data appear to demonstrate longer-duration longer-duration performance effects. Performance was poorer near midnight than at the early test time, but the difference was significant for overall D-A performance only in the placebo condition. At the second test time, scores were better with cocaine than with placebo. VIG RTs were significantly slowed at the second test time with 5 mg or 96 mg cocaine; with 126 mg there was no significant difference between test times. A trend toward poorer performance was observed on the morning after cocaine in comparison to the morning after placebo. (A)
Abstract