Could Humans Survive Years Without Sunlight?

How Sunlight Aids in Survival

• Sunlight aids the body in producing Vitamin D, which in turn aids in calcium absorption. Without vitamin D (and calcium) we would develop diseases like rickets, which causes malformed bones and teeth. Also true, with insufficient calcium we can develop fatal spasms of the larynx. Still, we can digest vitamin D through a diet including fatty fish, fortified milk, or simply as a dietary supplement in pill form.

  We can survive without direct sunlight, but it might be a moody, sullen life. Sunlight boosts the body̵7;s production of serotonin, which in turn regulate sleep and moods.

Survivors of No Sunlight

• Consider the horrific case of the Austrian Josef Fritzl, who held his daughter Elisabeth captive in a basement cell in his home for 24 years, without natural light. There she bore him seven children, three of whom never saw the light of day until their release at ages 19, 17 and five. The case demonstrates that humans can survive (if not thrive) for more than two decades without natural light.

  Russian authorities in August 2012 discovered a cult that lived underground somewhere in the Republic of Tatarstan. Many of its juvenile captives had never seen sunlight, and yet all were reportedly in satisfactory condition.

The Earth's Food Web Requires Sunlight

• Plants require light to produce energy via photosynthesis, which they can do with artificial light. However, the Earth's existing food web, with plant life as its foundation, requires the immense energy of natural sunlight. Removing that source would destroy any plant life that relies upon direct sun, which would in turn starve any herbivores and carnivores in turn that lived in the wild. Only that life that we chose to protect in artificial environments would survive.

Without the Sun Itself

• This all begs the question, how would we survive without the sun itself? The answer is, briefly. We could expect Earth̵7;s average temperature, about 57 degrees Fahrenheit, to dip below 0 within a week.

  Popular Science suggests that humans could survive in submarine habitats in the deepest and warmest parts of the ocean, or in nuclear- or geothermal-powered habitats. Also, we could harness and survive with volcanic heat for several hundred years, but not indefinitely.