"Toast"

This condition is experienced by people spending time (longer than a vacation) residing in research facilities and stations in-continent on Antarctica.  Outward symptoms include irritability, mood swings, depression, insomnia, inability to focus and zoning out ("the thousand yard stare") for brief periods.

"Okay, they're toast."

The result of sensory deprivation for long periods, it is a condition unique to Antarctic residents caused by the numbing of the senses.  With only a limited palette of colors in the wintry landscape, a lack of native wildlife and other population producing ambient sounds and smells, plus a limited variety of foodstuffs during the isolated winter months, this deprivation weighs heavily on the human psyche.

The reversal of "toast" can also be debilitating when a resident returns to the color, noise and odors of the rest of the world.  This can cause headaches, hallucinations, inability to concentrate, overflow of emotions and general instability until the returning explorer acclimatizes to their new environment.