This Science Daily article, “Increased Light May Moderate Fearful Reactions,” seems to support an age-old truth: that the dark is scary. I try to be rational. I mean, really rational. But truthfully, when our power was out for two days, and I made the uniquely poor life choice to read the last 100 pages of Blindsight by flashlight while everyone else in my house was asleep.
Objectively, I knew no resurrected genetic vampires were outside of my door. But that didn’t stop me from being afraid.
This study looked at learned fear responses in mice, which is an interesting specification, just as much so in humans as in mice. Behavior and psychology are effected by previous experience, and it’s reasonable to expect that one major factor that would be encoded in a memory would be the level of light or lack thereof at the time the event took place. Therefore, an initial slight instinctive propensity for heightened fear responses in low-light conditions would presumably be strengthened by experience.
The article gives a good explanation of fear as we understand it:
Fear is a natural mechanism for survival. Some fears — such as of loud noise, sudden movements and heights — appear to be innate. Humans and other mammals also learn from their experiences, which include dangerous or bad situations. This “learned fear” can protect us from dangers.
Of course, the other side of that is irrational fears and phobias (trust a girl who had a year-long terror of escalators in childhood). On a more seriousness note, research such as this can have implications for people with anxiety and related disorders. While this field has been largely based in behavioral research in the past, this article discusses discovering the neural pathways (in this case, the visual pathways) responsible for detecting light levels and associating them with heightened or lowered fear responses. Further research along this line could discover cellular, and eventually molecular, influences on fear responses, paving the way for pharmaceutical and other therapies to mimic the effects of increased light on the visual pathways.
For once, I wasn’t able to find the article via my school library (I’ll be keeping an eye out for it–I think it may still be pre-publication). So I haven’t been able to research this subject in as much depth as I would have liked, but I did think of one interesting contradiction that might be answered by the full paper, but isn’t mentioned in this article: cortisol levels in the blood fluctuate on an approximately a 24-hour cycle, peaking around the time you wake up in the morning, and reaching its lowest level sometime in the middle of the night. This has to do, in part, with the usual schedule of eating and sleeping; cortisol levels increase when blood sugar level decreases–essentially, the body finds itself lacking food, and reacts on a very low level (at least at first) as if it’s starving.
Cortisol is, very simply, a stress hormone–it is released in increased amounts in response to fear, anxiety, infection, surgery, trauma, pain, illness–anything that induces physical or mental stress. So it’s interesting that, in normal circumstances, it’s lowest at night, when decreased light levels would seem to facilitate a fear response, associated with stress and therefore with cortisol.
Diurnal cycles such as this one are often modulated by light levels (think circadian rhythms). Possibly the influence of hypoglycemia (low blood sugar after a night’s sleep and therefore not eating) override the effects of light modulation on the cycle of cortisol release.