From Egypt’s Darkness to Night Vision: What Science and Torah Reveal

This week’s Torah portion describes the plague of darkness that struck Egypt. The commentators explain that this darkness was not merely the absence of light, but a creation in its own right. The verse says, “and the darkness could be felt,” meaning it was tangible, almost physical, to the point that it prevented the Egyptians from rising from their places.

That was the darkness in Egypt. What about the ordinary darkness we experience every day, or more accurately, every night?

Seeing in the Dark

When it is dark, we are unable to see colors. The world appears only in shades of light and dark, and color seems to disappear.

This happens because during the day, our vision relies on light receptors in the retina called cones. These cones detect color and allow us to perceive the full spectrum of the visual world.

At night, however, a different type of receptor becomes active, called rods. Rods are highly sensitive to low levels of light, allowing us to see in darkness, but they do not detect color. That is why, in the dark, we cannot see colors.

Why Darkness Makes Us Sleepy

Naturally, when night falls and it becomes dark, we begin to feel tired and go to sleep. Why does this happen?

When it is dark, the pineal gland, located in the center of the brain, releases a hormone called melatonin. This hormone signals to the body that it is time to sleep and helps regulate the body’s sleep-wake cycle.

Since the invention of electricity and artificial lighting, this natural process has been somewhat disrupted, because light is present even at night.

For better sleep, it is important to keep the sleeping environment as dark as possible. It is also recommended to dim the lights before bedtime and avoid screens, which emit light that interferes with the natural production of melatonin.