そろそろ寝る時間

it's almost time to go to bed

→ そろそろ
phrase Rare #41,859
it's almost time to go to bed そろそろ means that something should happen soon or that it is about time to do it. Often followed by だ, じゃないの, or sentence-ending particles such as ぞ and よ.
JA: もう遅いし、そろそろ寝る時間だよ。
EN: It's late, so it's almost time to go to bed.

そろそろ寝る時間だぞ

It's about time you went to bed.

そろそろ寝る時間

It's about time to go to bed.

そろそろ寝る時間

It's almost time for bed.

そろそろ寝る時間じゃないの

Isn't it about time you went to bed?