We may not live in caves anymore, but our brains haven’t entirely caught up.

Most people don’t fear darkness itself; they fear what it hides. That’s because sight is our dominant sense, and when we lose it, the brain kicks into high-alert mode.

Evolution hardwired us to be cautious at night, when predators hunted and danger lurked just out of view. Even now, your amygdala (the brain’s fear center) becomes more active in the dark. And in the absence of information, imagination fills the gaps with shadows, footsteps, and whispers that probably aren’t there.

Fear of the dark is ancient, and kind of smart. It’s not irrational. It’s instinct.