An aphrodisiac is a substance that is believed to increase the sex drive and the level of sexual arousal. A recent study indicates that caffeine might be an aphrodisiac for women who consume it infrequently. The study was based on the reactions of female rats, who showed a "notable increase" in their sex drive and more likely than other female mice to mate multiple times. From this data, scientists naturally felt that the behavior of these rats was likely to apply to human women due to their belief that the desire for females to have sex is a social construct of both species.

Caffeine is a mild stimulant and triggers the brain to respond in the same way, though on a lesser scale, as stimulants like cocaine and amphetamines. Drugs of this nature have an addictive quality and people who consume caffeine on a regular basis can develop a tolerance to its effects, while others will almost immediately feel a boost of energy.

The scientists who conducted the study also noticed an increase in dopamine levels in the brain following caffeine ingestion. Dopamine is a neurotransmitter that causes the parts of the brain that perceive pleasure to function, so an increase in dopamine would indicate an increase in happiness or overall satisfaction. Like so many artificial stimuli, the effects of caffeine do not last, and sometimes users will feel a sharp decrease in their energy level accompanied by irritability as the effects of the caffeine wear off.

One of the interesting parts of the study is that it specifically states that an aphrodisiac effect, if it occurs, would only be felt by women who do not normally consume much, if any, caffeine. Scientists seem to believe that it is the increase in dopamine in the brain that might have an aphrodisiac effect. Because the body acclimates to the effects of caffeine as a stimulant when it is done on a regular basis, it is not surprising to find that the increase in dopamine in the brain would be correspondingly less present or noticeable. With only rats and dopamine to go by, though, it does seem that the effects could simply manifest themselves as an increase in happiness, not necessarily as an increase in sexual desire. It is also difficult to wholeheartedly claim a substance to be an aphrodisiac when it only applies, or might apply, to a small subset of the population. For some women, it seems as likely that chocolate could be an aphrodisiac.