Only when use Dynamic Lighting (no any pre-baked lighting) and turn off Lightmass (Static/Stationary lighting by checking “Force No Precomputed Lighting” Property in “Lightmass” Category/Pane of “World Settings” Panel) and Rebuild Lights you can achieve the complete black colors in the middle of the night of each Day/Night Cycle. Otherwise your middle nights will be very brightest (light dark, not so dark)!
Note: this bug not always(???) occurs when creating default map level.
Hi Angel Tsvetkov,
From the appearance of your scene it looks like you’ve got a skylight in your scene. If you’ve setup a day night system in blueprint (I recommend this one as a starting point: A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums) you’ll need to also account for the skylight and setting it’s intensity to a lower value just like you would the sun when it’s below the horizon line.
If you use the tutorial I linked you can just add the following to the end of the custom events to get better results.
Let me know if that helps! 
Hi and welcome back, Thank you so much for your respond. I do not use Skylight (or AthmosphericFog or PostProcessVolumes), I have only one light source - DirectionalLight, connected to engine BP_Sky_Sphere actor. And the only way to achieve complete dark (not bright/light) night is to turn off Lightmass (unchecked “Force No Precomputed Lighting” Property in “Lightmass” Category/Pane of “World Settings” Panel). The other way is to set to 0.1 (from 1.0 by default) “Environment Intensity” Property in “Lightmass” Category/Pane of “World Settings” Panel.
Okay, I want to clear up a few things to make sure I’m fully understanding because there are a lot of terms here that are thrown back and forth that aren’t really connected.
You mention that you want a day/night cycle, which is only available via a dynamic lighting method sine lighting cannot be baked.
You mention that you’re adjusting things in lightmass, but if you’re using a dynamic light these aren’t going to factor in. Lightmass is not used for any part of dynamic lighting.
Here is my sample project with a day/night movable light: Dropbox - Error - Simplify your life
When I set this up I didn’t adjust antyhing other than turning the sun’s intensity to 0 when below the horizon.
Can you post a screen shot of your directional light’s detail panel? Can you also do the same for the World Settings? With both of these use the “eye” icon in the top right of the details panel and change it to “show only modified properties.”
Thanks!
I’ve looked at this a little more and this may be a combination of your reflection capture and the reflectivness of the materials being used.
Try removing the reflection capture and seeing if that helps. If it does, then by adjusting the brightness value along with possibly changing some of the metallic reflective values of the materials lessen the reflected lighting at night.
Let me know.
Hi ,
I removed the reflection capture (SphereReflectionCapture) and also put very different materials on the ground and the cubes, but there is no effect- I can’t achieve complete black.
I do not use AthmosphericFog or ProcessVolumes, only one DIrectionalLight and one SphereReflectionCapture which I turned off in Night mode (SetVisibility uncheck via blueprint showing on the BlueprintGraph picture).
For now I discovered only two ways to achieve complete black and real colors in the middle of the night in Day/Night cycle:
1st way)Set to 0.1 (from 1.0 by default) “Environment Intensity” Property in “Lightmass” Category/Pane of “World Settings” Panel;
2nd way)Turn off Lightmass (Static/Stationary lighting by checking “Force No Precomputed Lighting” Property in “Lightmass” Category/Pane of “World Settings” Panel)
I’m still a little confused. You continue to reference Lightmass settings being adjusted but you also mention you’re using a dynamic day night cycle. These two do not work in conjunction.
If you are using a dynamic movable light for a day night system the lightmass settings will have no effect on the scene since these only work with baked lighting from Stationary or Static lighting.
Did you take a look at the example project I have above that can get fully dark with settings being changed in the materials of the BP SkySphere, the SKylight, and The dynamic light.
You can take a look at the video linked above and you will see the results on the first cycle with the skysphere. I stopped and set the next cycle for the skysphere to not render to show you that it can get fully dark. IF you need the sky to get darker you’ll need to adjust things through the BP_SkySPhere event graph to affect the material. Or you can setup your own skysphere and adjust the materials accordingly.
Hi ,
Thank you so much for your detailed info. I understand the difference. I just notice that when use Day/Night Cycle without Lightmass I achieve the dark night (correct colors), but when use Lightmass with “Environment Intensity”=0.1 I achieve almost dark night (approximately correct colors). And when use with “Environment Intensity”=1 the colors of night are already not correct – they are bright. So Lightmass in dynamic regime have some small influence. That is my point. Thanks