The effects of cigarette smoking on overnight performance.

Fifteen healthy smokers and 15 non-smokers were enrolled into this study investigating the effects of smoking on overnight performance. Subjects arrived at the test centre at 1930 hours and were assessed at baseline (2000 hours) and at 2200, 0000, 0200, 0400, 0600, and 0800 hours on a battery of tests (including Critical Flicker Fusion, CFF; Choice Reaction Time, CRT; Compensatory Tracking Task, CTT; Short Term Memory Task, STM; and the Line Analogue Rating Scale, LARS). Results showed that the performance of the smokers was more consistent with baseline measures than that of the non-smokers, which became more impaired throughout the night on a number of tasks [CFF (P < 0.005), Total Reaction Time (TRT, P < 0.05), CTT (P < 0.05) and the Reaction Time (RT) aspect of the CTT task (P < 0.0005)]. The Recognition Reaction Time (RRT) aspect of the CRT task showed that the performance of the non-smokers became more impaired from baseline (P < 0.005), while that of the smokers remained at baseline levels until 0400 hours, when it deteriorated to become comparable to that of the non-smoking controls. Subjective sedation ratings (LARS) resulted in comparable levels of impairment for both study groups (P < 0.00005). Findings from the STM task failed to reach significance. These data suggest that when performance is being measured overnight, smokers show little or no impairment, whilst the performance of non-smokers showed performance decrements.