PUT TO BED 寝かせる

To put a child to bed is to help him/her get ready to sleep by, for example, helping or encouraging him/her to put on his/her pajamas, making sure that he/she is comfortable in bed, or reading a story to him/her.
put (a child) to bed は、子どもの寝る準備を手伝ってやる、例えば、パジャマを着るように促したり、寝心地がいいか確かめたり、本を読んでやったりする、つまり、寝かせる、という意味です。

I try to get home from the office in time to put my daughter to bed.
(a two-year-old boy to his father)
a: Daddy, can we play another game?
b: No, it's time to put you to bed. Now get into your pajamas, and I'll lay out your futon. What book do you want me to read to you tonight?
By the time I've put little Billy and Scott to bed, I'm usually so tired that I go right to bed myself.

英会話レッスン Now that the kids are in bed, it's your own time. Spend it well!