Kava is a drank produced from the roots of Piper methysticum.
It is in use on the Pacific islands, and since 1981 it has also been in use in Arnhemland (Australia).
It is a mildly stimulating drug, producing euphoria; larger doses cause relaxation of the muscles, eventually acting as a sedative: (note 76)

At the beginning conversation comes in a gentle, easy flow and hearing and sight are honed, becoming able to perceive subtle shades of sound and vision.
Kava soothes temperaments.
The user never becomes angry, unpleasant, quarrelsome or noisy, as happens with alcohol...
When consumption is excessive, however, the limbs become tired, the muscles seem no longer to respond to the orders and control of the mind, walking becomes slow and unsteady and the user looks partly inebriated.
He feels the need to lie down.
The eyes see the objects present but cannot or do not want to identify them accurately.
The ears also perceive sounds without being able or wanting to realise what they hear...
The user is prey to exhaustion and feels the need for sleep more than any other sensation.
He is overcome by somnolence and finally drifts off to sleep. (note 77)