Your sentence is almost correct and very clear! Here's the original sentence:
At night, when other birds sleep, nightingales start to sing their melodious songs.
It is grammatically correct. However, to make it a bit smoother, you could say:
"At night, when other birds are asleep, nightingales start to sing their melodious songs."
Explanation:
- Using "are asleep" instead of just "sleep" sounds more natural because it describes the state of the other birds at that time.
- Other than that, your sentence is good and easy to understand!
Great job!