日夜

日夜

Day and night; always.

Here, '日夜' emphasizes that the activities are performed independent of day or night time.

日夜を問わず救援活動を行っています。

Rescue activities are conducted regardless of day or night.

Here, '日夜' is used to mean 'day and night,' indicating continuous exertion.

日夜努力を続けています。

I continue to make efforts day and night.

Here, '日夜' is employed to highlight the constant activity of research throughout the day and night.

彼は日夜新しい技術の研究をしています。

He researches new technologies day and night.