'At night' or 'in the night' - Usage & Difference

What is the difference between 'at night' and 'in the night'?

Both "at night" and "in the night" are used to refer to the nighttime, but they have slightly different usages.

At night

This phrase refers to the general time period when it is dark, typically from sunset to sunrise. It is used to describe things that happen regularly during the nighttime period.

I like to read at night.

The streets are quiet at night.

At night, the stars are beautiful.

She works at night in a hospital.

At night, the temperature is much lower.

It's hard to sleep at night when it's too hot.

In the night 

This phrase is often used when talking about a specific event happened during a particular night.

The power went out in the night.

I heard a strange noise in the night.

I woke up in the night because of a loud noise.

A storm started in the night and lasted till morning.

In the night, the moon shone brightly above the forest.

Summary

"At night" is more general.

"In the night" is more specific.