"The anxiety that’s been ricing my lungs turns steely and sharp when I see a pale wooden door built into a hillside, framed by lava rock."

"It looks like the entrance to Bilbo Baggins’s house. I go in. A stairway tumbles down to a windowless, 300-square-foot room with textured walls, a bathroom, and a wooden bed that smells like sage. A single low-wattage bulb hums faintly overhead. It’s controlled by a switch covered with a hard plastic guard, which makes it difficult to turn off and on. That’s the point. This room and two others like it in these secret woodlands are the heart of what might be the country’s only established commercial dark retreat. This is a spiritual place, where visitors pay good money to spend long periods of time in crypt-like blackness, devoid of all light and most sounds, in an attempt to uncage their minds and, they hope, discover something deeper within... I flip the switch to see just how dark the dark is, and terror presses into me like 13,000 vertical feet of seawater...."

Writes Tim Neville, in "The Darkness That Blew My Mind/Embarking on four days of total blackout, inside the sensory equivalent of a tomb, our writer went on a dark-cave retreat, the same one that quarterback Aaron Rodgers did" (Outside).