Okay, so imagine this:
The victims of this SCP's anomalous effect can only stay in sunlight. If they go into artificial light, close their eyes, or it becomes nighttime, they effectively go blind, and they see the SCP's creepy smiling face in this "darkness". Actually in any darkness. And, it gives them a constant fear, regardless of who it is. When their eyes are open, it looks as if they don't have pupils, only their Iris is present, so no light enters their eyes. Finally, their eyes are always wide open, in an attempt to escape this face, so they never sleep, are always scared, and many die of...fatigue, I guess, a few days later.