SLEEPINGB
=LAMBDA(n,
    LET(
        headsWakes, LAMBDA(x,
            IF(1 = x,
               {1,1},
               {0,2}
            )
        )(
            RANDARRAY(n, 1, 0, 1, TRUE)
        ),
        CHOOSE(
            {1,2},
            SUM(INDEX(headsWakes, 0, 1)),
            SUM(INDEX(headsWakes, 0, 2))
        )
    )
)