 You have to think of the way we make sense of the world is there are a lot of sensory inputs coming into your brain. And one of the sensory inputs is time of day, and when it's light out, we know it's daytime, and when it's dark out, we know it's nighttime. But if you take away some of that sensory input, and that can happen when the sun goes down, it can increase somebody's confusion who already has significant cognitive impairment.