Combinations - Kava kava (tranquilizer) and Caffeine (stimulant)

[Richi]

Why does it seem that the traditional rule about not mixing 'uppers and downers' does not apply here?

I say this because many sources openly advocate consuming coffee with kava to counter-act the sleepy effects it evokes.

[EDIT] It would appear to be so because Caffeine affects the cAMP pathways, which control the metabolism of sugar and other biochemical processes. Whereas traditional stimulants such as cocaine or methamphetamine affect serotonin and dopamine levels in the brain. If someone could shed more light it would be greatly appreciated. [/EDIT]