How Does Darkness Manipulate the Brain?

PMT 2014-050b

1. How do the other senses react when we can’t see anything?

If the visual cortex is no longer processing any visual stimuli, it simply searches for other tasks. After as little as 24 hors in total darkness we are able to smell better, perceive sound more clearly, and learn Braille more quickly. However, within 24 hours of reexposure to light, the primary visual cortex is retrained and once again reacts only to visual stimuli.

2. How fast do the eyes become accustomed to darkness?

Our eyesight adapts to the darkness gradually and sill achieve maximum sensitivity after around 40 minutes. The key: rhodopsin, a light=sensitive pigment that is found in the rods — the cells of the retina that make it possible for us to visually orientate ourselves at night via night vision — and functions even in very low-light conditions.

3. Which signals does the brain send out at night?

When it’s dark, the pineal gland is operating at full tilt. The small endocrine gland in the diencephalon (“interbrain”) produces the “sleep hormone” melatonin and regulates our sleep-wake cycle. The body prepares itself for sleep. What follows is a chain reaction of relaxation: Heart rate, blood pressure, and body temperature decrease, and breathing becomes calmer.

4. Where does fear of the dark originate?

Our senses are constantly in work mode. But in the dark the sudden absence of all visual stimuli causes the thalamus to sound an alarm. WE get scared. The body releases both adrenaline and serotonin. Meanwhile the amygdalae are busy comparing sensory impressions with memories. Have we ever experienced, see, or hear anything like this before? In this way, the ‘”fear control system” in the brain tires to assesses the situation.

From: Ideas & Discoveries magazine (January 2014, p. 18)

Blame It on the Brain
by Edward T. Welch
Depression, Attention Deficit Disorder, Alcoholism, Homosexuality.
Research suggests that more and more behaviors are caused by brain function or dysfunction.
But is it ever legitimate to blame misbehavior on the brain?
How can I know whether my brain made me do it?
See more study materials at:

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