Skin potential responses of mentally retarded children during nocturnal sleep.

Skin potential responses (SPRs) of 38 mentally retarded children were studied during their nocturnal sleep. One subject exhibited no SPRs; 19 of the 37 subjects showed more SPRs (Type A); 11, no predominant ones (Type B); and 7, fewer SPRs (Type C) during quiet sleep (no rapid eye movements, NREM sleep) than in active sleep (REM sleep). Types B and C tended to be observed more frequently for subjects with abnormal clinical EEGs than for those with normal clinical EEGs. Because investigators have established that nonretarded subjects of 3 months and over exhibit Type A, SPRs may be used as an additional assessment for diagnosis of mental retardation in early infancy.