Like many children, I used to be afraid of the dark. I didn't know what creepies and or crawlies lurked about and I wasn't about to find out on accident. I think being afraid of the dark is a natural evolutionary impulse. Humans rely on our senses to protect us from danger, so when one of them is compromised we feel a little uneasy. Sure, there was probably nothing nefarious lurking in the crevices of my childhood bedroom, but what if there was? I wasn't going to let any under-the-bed goblins come out and get me, so I slept with a nightlight on for most of my life.
As an adult, the only blinds I have installed are slightly sheer, so my room is never fully dark. The boogeyman doesn't go away just because I'm an adult! But now, at least I have memes to keep me company at night. Their hilariousness wards off any evil spirits.