ANSWER:

They must sleep in their rooms at such ages as they can see and recognize nudity and awrah. 

Lock your doors at night and suppress your emotions and they will learn.

QUESTION: I have 2 boys (5,3years) and they always Slept with us in our room and our bed space. We never let them sleep separately . But now, as they are growing, they cry and shout if they see we spouse together(hugging or sitting close). What’s the age the kids should sleep separately by Islam? And what can be done to keep them in their rooms and not run back to us at midnight?