My world isn't dark at night

Hi , I made this example and two others. I want to achieve almost complete dark in the middle of the night. Here is two pictures in the middle of the night with “Environment Intensity” with 0.1 and 1.0. Because I do not use AthmosphericFog or ProcessVolumes, only one DIrectionalLight and one SphereReflectionCapture which I turned off in Night mode (SetVisibility uncheck via bluescript showing on the BlueprintGraph picture), the last possible option is to manipulate something in BP_Sky_Sphere? Do you know what exactly?Thanks