AdvertisementInside The Hole: What Happens To The Mind In Isolation?April 03, 2017Shankar VedantamMaggie PenmanRenee KlahrJennifer SchmidtRhaina CohenTara BoylefacebookEmailIn the Secure Housing Unit (SHU) of Pelican Bay State Prison, inmates spend 23 hours a day alone in their cells. (LA Times via Getty Images)