Sensory deprivation is a condition where someone is deprived of normal sensory input like sight, sound, and touch for an extended period. It can cause perceptual, cognitive, and emotional disturbances like hallucinations, anxiety, and mood changes. There are two main types of sensory deprivation therapy used - chamber REST which involves lying in a dark, soundproof room, and flotation REST using isolation tanks filled with salt water to allow floating. While short periods can be relaxing, extended deprivation poses risks and requires monitoring by nursing to assess clients and prevent injuries from perceptual issues.