I disagree. Last night dd2 age 7mths woke up- saw us sleeping in the bed and promptly rolled over and went back to sleep. I was watching her in bed as I knew she had woken cos her breathing changed. I think my husbands snores comfort her.
Dd1 age 29mths ALWAYS has slept fabulously in our room whether on a mattress on the floor or in our bed. Avg sleeper in her room.
I think humans in general sleep better near other humans.