The dark can be scary and intimidating. Especially if you're alone. (Then again, maybe it's worse if you're NOT alone... I mean, who wants to be left in the dark with a serial killer??)
Anyway, if you're the one in the dark, it's a big relief for someone to shed some light. The thing is, depending on where you are and what you're doing, the type of light matters significantly. Sometimes plugging in a little night-light is the perfect solution. It brightens the room a bit so you don't have to worry so much about the unknown, but doesn't keep you from resting.
Sometimes a flashlight is the right tool - it lets you see your path without disturbing someone else. And if you feel the need to alert others of what you see, flip the light switch and illuminate the whole room.
Now, there are occasions that demand a spotlight, but those times are sparse - and it's almost NEVER a good idea to throw a spotlight on someone who's been in the dark. It can be downright cruel. His/her eyes won't have time to adjust... a light so intense won't help him/her, but will only cause pain and panic.
(Really, think about it. What's the first thing a person does when a bright light is suddenly thrown on his face? CLOSES his eyes - now, who does that help? ... And how often does someone flinch when a candle is lit?)
The other thing about putting a spotlight on someone? It leaves YOU in the dark.
Yup, this is all a big metaphor. I like to assume you get it, but just for the record: Don't push so hard for someone else to see things the way you do. Even if you are doing it out of genuine concern... because if you DO sincerely care, you'll want to take the more effective approach. Usually that means "little by little" and not "a lot at once."