Are people who are afraid of the dark, more likely to believe in ghosts?.?

Don't quote me on it, but I would imagine they're more likely to be skeptical in their disbelief.

Much of being scared of the dark stems down to a fear of the unknown, and being deprived of light drops our sensory input to about 5%. Taste and touch requires too much proximity for something that would hurt you, so when you're in the dark the only senses you can rely on is smell and sound.

The topic of ghosts is a feild unknown to most of us, and even those who have studied the phenomena have little to go by as it cannot be scientifically explored. Despite the fact that ghosts can't really harm you, it is still freaky to experience something that cannot be explained by natural merits. So ghosts are akin to the unknown, as is fear of the darkness.

Those that don't believe in ghosts are generally more assertive in their belief and reject any and all things supernatural. So with them, being afraid of the dark is more dependent on location. In the comfort and safety of their own home there would be very little if any fear. If they are in foreign territory, however,  they'd be more cautious of every sound and every step.

However a person that believes in ghosts and is afraid of the dark may still need to sleep with the night light on despite being in their home because ghosts transcend the physical safety of ones surroundings.

No, not really.  They're two very different things.

Aside from nyctophobia, which is not the same as a classic fear, there are actually reasons why many people are afraid of the dark.  First, our species does not have good night vision, and what you can't see can hurt you.  Second, and this goes way back to the days when we all lived up a tree, the animals that want to eat us have extremely good night vision.  They also have sharp claws and teeth, which we don't.  We don't even have thick hides, armour or the ability to run fast.  Our only natural defence as a species is our huge powerful brains, which allowed us to build weapons and fortifications.

We've gotten pretty good at building weapons and fortifications, which means we're well protected from the things with sharp teeth that hunt in the night.  But our survival instinct doesn't care, it just knows that those things are out there whenever it's dark.