In “Little Monsters,” light is used to destroy the monsters. The 1989 fantasy comedy establishes that the creatures are vulnerable to bright light, especially sunlight, which causes them to collapse into piles of clothes or disappear.
The film follows Brian Stevenson, an eleven-year-old who discovers a monster world beneath children’s beds and befriends Maurice, played by Howie Mandel. Brian eventually learns that Maurice and the other monsters were once children who were transformed after spending too long in the monster world.
Light becomes the key weapon in the final conflict. Brian and his friends gather powerful lights and use them against Boy, the ruler of the monsters. They defeat Boy by shining so much light on him that it kills him. The movie also shows why timing matters: the children must escape before sunrise, because remaining in the monster world risks turning them into monsters themselves.
A common mix-up is confusing ordinary sunlight with the portable flashlights used by Brian and his friends. Both represent the same weakness, but the practical weapon in the climax is artificial light.