2 year old wont go to sleep at night alone.

Tegan

My 2 year old is fighting going to sleep at night alone. Hes fine during the day for a nap aslong as I leave his door open. but at night even if he is absolutely exhausted he still wants me and only me to lay next to him until he fall asleep. He sometimes wakes during the night and screams until I turn on a light then he goes straight back to sleep. Is he all of a sudden scared of the dark? Maybe hes been having nightmares? Any advice on how to deal with scared toddler that doesnt require room sharing? Just brought a night light will try tonight.