There is nothing beneath the bed. Your mind is playing tricks on you. You just need sleep. WASD to move.
If you are confused and did not figure out the story or have not read "The Tell-Tale Heart" by Edgar Allan Poe, scroll down. SPOILERS for both the game and the short story, as they follow a similar path of events. The protagonist of this game commits murder and hides the corpse under the bed in an apartment he rented. As the days pass, the gravity of his actions slowly take an effect on the way he sees himself and the world around him. The parasites that infect his body represent the growing weight of his actions "consuming" him (taken literally in the context of the game). On day four, the eyeball creature represents the growing paranoia he has of people finding out what he did, leading him to shut all the curtains. On day five, the banging on the door is actually just the hotel staff, who are confused as the room was supposed to be vacant. In the end, he admits to everything, crushed by the immense guilt he feels for what he has done. Nobody had suspected him up until the confession. Had he left the apartment on time, no one would have ever known it was him who committed the murder, and he would have been free.