They are predominantly active at night and spend most of their waking hours feeding .
Because they get so little energy from their diet , koalas must limit their energy use and sleep 20 hours a day ; only 4 hours a day are spent in active movement .
koalas are predominantly active at night and spend most of koalas ' waking hours feeding .
Because they get so little energy from their diet , koalas must limit their energy use and sleep 20 hours a day ; only 4 hours a day are spent in active movement .