Darkness doesn't kill humans. We have many ways to combat the dark, like flashlights, torches, fire, flares, glowsticks, night vision goggles, etc. Also, if you're referring to walking out in the dark, like out in the woods or walking into a cave, then fear not. If you are a sufferer of vitamin A deficiency, consuming beta-carotene from carrots also helps one see in the dark.