So all I remember is a guy visiting a couple at their home (flat) and he is being followed by monsters of some sort but only if the lights are on or off, one or the other I cant remember which… at one point someone goes to the woman who lives upstairs who is pregnant and I’m pretty sure she gruesomely gives birth to a mutant looking baby. In the end I think it turns out he is actually losing his mind I’m not 1oo% sure… I know it’s not much to go on but its driving me mental.. I watched it on DVD at a friends about 5 years ago.