Table 2.

Mean (SD) participant characteristics by Condition (Caffeine/Placebo)

	Caffeine	Placebo
Age	19.0 ± 1.0	19.6 ± 2.5
Gender (F/M)	18/2	16/4
Number of non-habitual caffeine consumers	4	4
Gender (F/M)	4/0	3/1
Caffeine (mg per day*)	223.1 ±152.2	171.6 ±72.7
Number of smokers	2	2

*Excluding non-consumers