Even though being afraid of the dark sounds childish, our fear of the dark is an evolutionary trait that we picked up to survive real-life predators stalking the night. Researchers have hypothesised that this innate fear stems from a point of human history when we were nowhere near the top predators we are today. Humans only really became super predators with the advent of technology, which wasn’t that long ago.
Before technology, our ancestors were constantly on the look-out for predators that wanted nothing more than to chow down on human sandwiches. To make that even scarier, most of these predators hunted at night - a time of day when we are especially vulnerable to attack because of our relatively poor eyesight.
This means that it was super important for our ancestors to stay safe in the middle of the night. If they didn’t, they’d die. Over the years, this nightly fear became instinctual, and we still experience it today as a form of mild anxiety.
Source: http://www.sciencealert.com/here-s-the-evolutionary-reason-why-we-re-afraid-of-the-dark
