S/O gets turned on in the middle of the night

I’ve noticed occasionally my S/O will be turned on in the middle of the night and want to either have sex or get each other off.

Two nights ago I woke up to him trying to get me off with his hand and I was sorta out of it because it was 4 am and could feel him then stopping and just pressing against my leg so I knew he was turned on.

Does this happen to anyone else?