We’ve all been there. Lying in bed at night in nearly complete darkness, a small voice whispering that something ominous could occur at any moment. In some way, we’re all afraid of the dark and probably have been since early childhood. In the days when the nightlight was a necessity, we could’ve sworn that there was a monster under the bed or in the closet. Most of us mostly outgrew it, but for some, the fear of darkness is still a problem. When what kept us up late into the night affects our performance well into the next day, there’s a real need to understand what’s going on. The fear of nighttime or darkness may seem pretty silly on the surface, but it’s no joke for some. So, why is our species prone to being afraid of the dark? It seems that it’s actually a built-in adaptation that we’ve inherited. 


Irrational Fear

Nyctophobia is defined as an intense, irrational fear of darkness or of night. It’s the kind of fear that interrupts normal life. People with this phobia really don’t fear anything particular in the darkness but are afraid of the darkness itself, the apparent nothingness, the mystery that it holds. It’s a blank slate upon which our deepest fears can be inscribed. What could be out there, rather than what actually is, compounds the irrationality one’s mind is conjuring. Even when a person is sharing a bed, those sleeping comfortably nearby aren’t much comfort. The insomniac is very much alone in the gloom. 


Hardwired Horror

This phobia is most likely an evolutionary adaptation that’s hardwired into human brains as a means of protecting their hosts from the dangers that lurk in the dark. Our earliest ancestors were designed to fight or flee from a threat. These days, although we’ve retained the fight or flight reaction, it’s more psychological than physical. Now there’s nowhere to run or hide; the best weapon we have is our ability to reason. Unlike our earliest ancestors who met threats as they arose, some of us often stay at a relatively constant state of alert. Our phobia keeps us up when we ought to be resting.


Uncontrolled Imagination

Most of us can probably relate to the anxiety that builds during insomnia. Lying in a dark, quiet room, one’s mind races through a minefield of sinister thoughts—problems at work, the news story about the home break-in... “Did I remember to lock the front door?”... Meanwhile, the tossing and turning seem like they will continue all night. 


Virtual Blindness

We as humans are basically blind in the dark. However, when one sense is very limited, other senses are amplified in order to compensate. So, this “blindness” could cause us to notice sounds that we may not be conscious of when all of our senses are at peak performance. In some ways this compensation is good. However, the heightened sense of hearing can also exacerbate the feelings of anxiety and intensify the fear to an almost primal level. It may sound illogical, but the introduction of a dim light may even contribute to this anxiety rather than dissolve it. People’s imaginations are excellent at creating their own “monsters” from mere shadows. Imagine the effect a full moon has against tree branches blowing in the wind. Creepy. What’s worse, extreme fear can cause physical reactions such as goosebumps, which can give the eerie perception of being touched. 


Increased Vulnerability

Our earliest ancestors had to be extremely vulnerable living out in the wild. Their senses weren’t as acute as many predatory animals. So, the animals could be pretty closeby before humans became aware of their presence. The only defenses our ancestors had were fire and whatever weapons (e.g., spears, clubs, knives) were quickly accessible. So, how much fighting or fleeing was really going on when they couldn’t see more than a few feet into the complete darkness? Humans didn’t generally have the speed or agility needed to fight off a large predator, anyway. So, just as our ability to reason is our biggest defense against our phobia of darkness, it is also what has ultimately saved our species.