Explanation:

- C: We spend about one third of our time sleeping.

- This sentence introduces the topic by stating a general fact about sleep.

- B: However, the body utilizes the sleeping time effectively.

- This connects with the previous sentence. It contrasts the passiveness of sleeping with the active work the body does during that time.

- D: It produces energy and releases hormones for repair and growth during the night.

- This sentence explains what the body does during sleep, as introduced in sentence B.

- A: The brain is active too during sleep, sending messages for the heart to beat regularly.

- This adds additional information on the brain's activities during sleep, completing the explanation of how active our bodies are.

?? Correct Order: CBDA (Option: 3)

- Your interpretation of the sequence aligns with the logical flow of the sentences.