Using the definite article the before night

Question

In the sentence given below

Other forms of harassment that plumbed new depths included ringing the doorbells of diplomats at late hours of the night to intimidate them, and even tailing cars ferrying diplomats’ children from school.

Why the is used before night.

Answer 1

"Late hours of the night" is slightly idiomatic but fully correct.

It's normal to use 'the' when describing a time of day.

I will visit you in the afternoon.

I was woken every day early in the morning