meaning - "our bodies lose their rhythm" vs. "our body loses its rhythm"

In this above situation, the question is that “What happens if we change our sleep pattern often?” and my brother had to fill in the blanks.

A: ______ ______ ______ ______ ______ .

So he answered, “Our bodies lose their rhythm.”.

But his teacher said the answer was wrong. The correct answer which she wants is

“Our body loses its rhythm.”

My brother’s answer is wrong?
I would like to know if this answer is incorrect or not and if not, what is the difference in meaning between them.