Has he watched anytning recently or been scared in any way??? Dh just the other day told Isabella to stay away from the garage because there are spiders in there.... next thing I know when I was bathing her that evening (and we saw a little spider crawling), she said "spider....scared"
. I could have killed dh. I try not to use those words or have her frightened in any way. Anyway off the topic here but maybe ask her....
Could also be related to his daytime sleep and routine in general. Does he still nap and what times? What does his whole day look like???
Sitting with him or taking into bed is a good enough reason for toddlers to be waking at night as well. If she had done it oncem he might just be expecting it again and again.
Here's a link to sleep training for toddlers - tell your friend to chose an option and try and stick to it.
https://babywhispererforums.com/index.php?topic=63896.0Good luck and let me know how it goes
Layla