"Quiet time" refers to a period when it is desired or encouraged to be calm, silent, and reflective, often allowing for relaxation, thinking, or engaging in peaceful activities without distractions or noise. Full definition
You can use that time — often after lunch — for quiet time for your child to read and relax. (caringforkids.cps.ca)
I am a kind and gentle outgoing person who is a gentleman and very comfortable with myself and enjoys spending quiet time with my companion or going out for a fun night. (sugarmommaclub.com)
Or if they need a bit of quiet time in the day they can disappear to their room and listen to music or an audiobook. (mummymummymum.com)