Grass glows over time, help?

I was making a scene with terrain. When I started adding grass I fiddled with the sizes and the color to get it looking nice. After I finished, I tested my scene to find that the grass gets brighter over time. I looked into it and have checked all my project settings for a fix to no avail. I was wondering if anybody has the same issue or knows a fix for the issue. The picture attached is what I'm seeing. The top image is how the scene is supposed to look, but the bottom is the game running after a minute and some.