Because Afrikaans uses is as the present-tense form of to be in all persons.
Examples:
So unlike English, the verb does not change between am / is / are in the present tense. That is one of the simpler parts of Afrikaans grammar.
Because after a linking verb like is, Afrikaans normally uses the adjective in its basic form.
So:
Notice the difference:
This is a very common pattern in Afrikaans.
You would use the Afrikaans double negative:
Die deelnemer is nie bewusteloos nie.
Afrikaans usually uses:
So this is a very important structure to learn early.
It normally means physically unconscious.
If you want to say unaware in the sense of not knowing something, Afrikaans often uses onbewus instead.
Compare:
So this is an important meaning difference to keep in mind.