[MariJo7]

Perhaps he is old enough to understand your need for some privacy, if you discuss it with him. You could tell him that everybody needs some time alone, especially grown ups, in order to function properly. Just like we need food and sleep and prayer, we need some "time alone". Perhaps you can ask him to "help" you to get your "time alone". Kids can be very helpful if they know how to do it.
Perhaps you can introduce the subject like: You know what happens when a person never eats. Yep. He or she will get sick and very weak. And if we do not pray, we will become weak and we can not do the right thing God wants from us. And in the same manner, we also need a little bit time every day to be alone, to think and to plan. Especially grown up people need that kind of time. It is like charging a battery of your cell phone. Mommy also needs some time alone in order to charge herself for the next day. Can you help Mommy with that?
Then you could tell him that your "battery charging time" is after you have read the Bible with him and it is very important for you and if he can help you with it. And tell him how: of course he can always ask if there is a real problem like pain or fear, but if everything is fine, he could pray for you or do something else that's quiet if he can't sleep.
You certainly need some time. Perhaps there is a way to tell him it is for his benefit too.