SpongeBob reads a scary book before bedtime. Because of this, he sees scary creatures when he turns off the light, such as the chair being a monstrous brain beast and a coral branch tapping the window as a monster's hand.
When at the Krusty Krab, he gets terrified of a pot on his head, then he tells Mr. Krabs that if he blinks, he sees something scary, he then tries not to blink, but it does not work, he then gets spooked by the dark in the freezer when Mr. Krabs wanted him to get some fresh patties. Mr. Krabs tells SpongeBob to get a night light so he won't be scared of the dark. He first buys one and however, buys more when he finds darkness in his house. Eventually, there are thousands of night lights in every room.
Patrick wakes up and sees SpongeBob's house lit up. He thinks SpongeBob is throwing a party and goes to his house, but SpongeBob warns him about the dark so he brings his rock inside SpongeBob's pineapple. While getting more night lights, Squidward tells them that they have too many lights and that the creepy creatures of the dark are just their imagination. While SpongeBob and Patrick get a lighthouse, it makes an M in the sky so Mermaid Man and Barnacle Boy come. Meanwhile, the Moth, one of Mermaid Man's enemies who he has been searching 57 years for, finds the light, but SpongeBob traps him inside the lighthouse. The Moth then carries the lighthouse along with the pineapple.
SpongeBob and Patrick are alone in the dark until the sun rises. Patrick goes up to get it, thinking it is a light and SpongeBob falls asleep. Patrick comes down again on fire shouting "Too much light!"
The original airing had Patrick saying "SpongeBob, can I sleep with you again tonight?" This was changed to "Sleepover!" in reruns, possibly because it sounded like implied homosexuality.
The episode was available on the Friend or Foe? DVD, released earlier in 2007, before it aired on television.
The beginning of this episode is similar to "Krab Borg."
SpongeBob develops a fear to something after seeing something scary and keeps overreacting in both episodes.
The novel SpongeBob reads breaks its fourth wall, talking about the author dying before finishing the story.
SpongeBob develops boogophobia, a phobia of the "boogeyman."
When SpongeBob looked at the bathroom being dark, if one would look closely (or possibly stand up), his pet scallop can be seen.
Running Gag: SpongeBob getting more lights.
SpongeBob chooses to buy too many night lights, when he can just turn on all the lamps in his house.
It is revealed that Squidward has a mirror on his bedroom ceiling.
The episode jumps out off topic, from night light matters to a Mermaid Man and Barnacle Boy conflict.
When the lighthouse shines its light through the pineapple, at first the "M" looks like it has more of a curve, but when Mermaid Man finds out the signal is a false alarm, the signal looks like a normal "M."
The Moth is voiced by Mark Hamill, who portrays Luke Skywalker in the Star Wars films.
When Moth lifts up SpongeBob's entire pineapple, only the very top should go since it detached from the rest of the house.
Double Irony: A normal child with a fear of the dark would usually sleep with only one night light. SpongeBob, out of desperation and fear, bought way too many night lights to light up the pineapple in the most impossible way since one night light wasn't enough for him. And he wasn't able to get any sleep until the end of the episode.
This is the first time SpongeBob struggles to go to sleep. The second is in "New Digs" and the third is in "InSPONGEiac."
This is the first time that Mermaid Man and Barnacle Boy appear in an episode that does not have their names in the episode title.
When Patrick was in SpongeBob's mouth after Squidward scared them, he came out after Squidward told them it was him, but without his sleeping hat. The next shot he was seen, his hat is back on his head.
When SpongeBob asks Mermaid Man and Barnacle Boy if they're here to protect them from the darkness, he doesn't have any legs.
When SpongeBob and Patrick meet Mermaid Man and Barnacle Boy they are all outside. After the shot with the letter "M," they are all in the pineapple.
It is possible they went in the pineapple off screen.