Solitary confinement is a special form of imprisonment in which a prisoner is isolated from any human contact, though often with the exception of members of prison staff. It is sometimes employed as a form of punishment beyond incarceration for a prisoner.

The effect of solitary confinement on mental health has been studied and discussed by psychiatrists since the 1930s. According to psychiatrist Stuart Grassian, a psychiatrist who studies solitary confinement, inmates are more likely to under-report than to over-report its effects (i.e., “Some of the guys can’t take it—not me”). Grassian has found that common effects of solitary confinement include:

  • increased sensitivity to stimuli,
  • hallucinations,
  • changes in perception,
  • cognitive problems including memory loss,
  • difficulty thinking,
  • Impulsiveness.

These effects may together constitute a unique syndrome, sometimes called “SHU syndrome”. Others term it “Social-Sensory Deprivation Syndrome”. Grassian’s 1983 study of inmates at Walpole State Prison is credited with identifying (duration and degree of) sensory deprivation as an important variable in mental health outcomes.