GIVE ANSWERS - English

”diurnal” is a very formal way to express something which happens during the day. Usually, it would be used by biologists to describe animal or plant behaviour during daytime hours.

The antonym for ”diurnal” is ”nocturnal”. For some reason, ”nocturnal” is used by English speakers much more than ”diurnal” - even to describe people who are active at night.

A normal way to describe for people active during the day would be ”my daytime life”.

”My diary life” sounds a bit strange, except perhaps as a description for your life as written in a diary.