Night Footsteps and Vanishing Figures in a Rented Apartment

At one point my aunt and uncle lived in rented apartments. Over 2 years they changed about 3-4 apartments, and in one of them strange things happened. At night they often woke up from the sounds of footsteps, sometimes in the next room behind the wall, sometimes in the hallway, sometimes right next to the bed. At first they blamed the neighbors, but then both of them saw some kind of fucked-up shit and got seriously freaked out. First my uncle woke up in the middle of the night, opened his eyes and saw a human silhouette next to the bed, which disappeared after a couple of seconds. Then my aunt, on one sleepless night, clearly saw someone walk past their bedroom down the hallway, even though my uncle was sleeping next to her and there couldn't have been anyone else in the apartment. Some time later my uncle was coming out of the toilet and saw some figure fussing around by the radiator in the kitchen, resembling a hunched-over person. He freaked the fuck out, flicked the light switch, but as soon as the light came on — the figure vanished. My uncle says he only managed to see the outlines, and they really did resemble a person bent low, groping around somewhere near the baseboard. Later my aunt saw practically the same picture, only in her case the figure was fussing around by the TV in the living room, and it didn't disappear right away but seemed to float toward the balcony, and there it dissipated like fog.

Notably, at first they didn't share this craziness with each other, because they blamed everything on fatigue, on "I imagined it," and so on. Only later did they somehow get to talking about the nighttime strangeness, and that's when all these cases came to light. Apart from the strange sounds and visions, nothing else happened in that apartment; my aunt and uncle lived there a couple more months and moved out. Basically that's all the paranormal stuff in their lives.