Hereditary factors in sleepwalking and night terrors

The families of 25 probands with sleepwalking and 27 probands with night terrors were studied. Eighty per cent of the sleepwalking pedigrees and 96% of the night terror pedigrees included 1 or more individuals, other than the proband, who were affected by sleepwalking, night terrors, or both. The authors' data appear to fit a '2 threshold' multifactorial mode of inheritance. This finding supports the hypothesis that sleepwalking and night terrors share a common genetic predisposition, with sleepwalking being a more prevalent and less severe manifestation of the same substrate that underlies night terrors. Heritable factors predispose an individual to develop sleepwalking and/or night terrors, but expression of the trait may be influenced by environmental factors.