Mood and performance effects of caffeine in relation to acute and chronic caffeine deprivation.

The mood and performance effects of caffeine deprivation (either 90 min, overnight, or at least 7 days) and ingestion (70 and 250 mg) were compared in young adults who were normally either moderate consumers (n = 49) or nonconsumers of caffeine (n = 18). Overnight caffeine deprivation produced dysphoric symptoms characteristic of caffeine withdrawal that were reduced, but still present, after longer-term abstinence. Acute caffeine intake affected the withdrawn consumers, nonwithdrawn consumers, and nonconsumers similarly. It increased jitteriness and decrease tiredness and headache. Furthermore, hand steadiness decreased as caffeine dose increased, whereas 70 mg, but not 250 mg, of caffeine was found to enhance performance on a simple reaction time task. These findings support the view that the negative effects experienced after overnight and longer-term caffeine deprivation play a significant role in influencing consumption of caffeine-containing drinks. Therefore, it would appear that to avoid the dysphoric symptoms resulting from both under- and overconsumption, regular caffeine consumers would have to regulate their caffeine intake fairly precisely.