The cavemen days were a long, long time ago, but human bodily behaviour in the 21st century is still proving to have qualities that originate back to this period. One of these aspects, is our night vision abilities.
New research conducted by Goethe University, Frankfurt, Germany, studied the brains of 14 males across six different times from 8am to 11pm across two days. The study revealed that our eyesight is at its best during some of the darkest times of the day - dawn and dusk - and it’s at its worst at 2pm.
Whilst it could sound rather ironic that our vision peaks when twilight falls at 8pm and in the hours before dawn at 8am, the experiment reveals how our brain and eyes have the same qualities that humans had back in the pre-industrial age.
Night vision. Why can we see best at dawn and dusk?
Before we knew about electricity and light bulbs, twilight was one of the most dangerous times during the day for humans, as it was when we were most under threat of facing nocturnal predators. Having strong night vision in poor light conditions in these times was immensely advantageous, as it would enable humans to keep a look-out and protect themselves during the night.
As our vision adapts to light conditions throughout the day, we have developed a way of seeing, even when low-light conditions make it much more difficult. Neuroscientists at Goethe University studied the activity of the human brain to see if there was a difference across a day - they found that there was, which shows how our bodies have an inner clock that can prepare our eyes for periods of darkness.
It’s not all in the eyes, it’s in the brain!
Interestingly, the changes in our ability to see during the day has nothing to do with our eyes adapting, but how our brains process visual signals. Background activity in the human brain is constant throughout the day - however, as night falls, this lessens in our visual centres.
Christian Kell from Goethe university explains that ‘you are sensitising your brain’; essentially, in order for us to improve our vision in poorer light conditions, our brain shuts down activity in the visual cortex. Ultimately, this allows us to process weak signals and see dimly-lit objects better.
The benefits of having this improved vision at twilight for us in the 21st century, is that daily activities such as driving may be easier as our perception of light changes.
- Peanut butter (result!) - this spread is rich in Vitamin E, which is a powerful antioxidant that helps with night vision. Peanut butter is also good for fighting age-related macular degeneration and cataracts
- Oranges - filled with Vitamin C and beta-carotene, oranges are a great way to keep your night vision healthy
- Kale - a superfood for supervision, this leafy green is full of lutein and zeaxanthin to boost your eyesight at night
- Egg yolk - just like kale, egg yolk is full of lutein and in addition has a rich source of healthy fats that contribute to good night vision
So, what other senses are sharpened at twilight?
- Hearing - Just like our vision improves as there becomes less light available, the same goes for our hearing which also derives from our natural instinct to protect ourselves from nocturnal predators. The brain suppresses activity in the hearing region of the brain, enabling our hearing senses to be heightened and allowing us to hear quieter sounds much more clearly
- Feeling warmth and pain - Also known as the somatosensory region of the brain, these senses become sharpened at twilight
Both of these reflect a key evolutionary advantage that ensured survival in the pre-industrial era, and whilst the majority of us won’t come into contact with a nocturnal predator like a lion during the night, it’s still pretty cool that if the case ever did arise, our vision and senses would be prepared.
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