Asperger syndrome (AS) is a neurodevelopmental disorder belonging to autism spectrum disorders. Both children and adults with AS have subjective impairment in the initiation and continuity of sleep, and studies using objective assessment are sparse. Twenty young AS adults with frequent complaints of low sleep quality were compared to 10 age-, gender- and education-matched controls without sleep complaints using polysomnography and spectral power analysis of slow-wave sleep. AS subjects displayed a similar polysomnographic profile as compared with controls. In spectral power analysis, a statistically nonsignificant trend towards decreased relative delta power and increased theta power in slow-wave sleep was found in the AS group. It seems that nonorganic insomnia, due to anxiety inherent in AS, is responsible for the low sleep quality in these subjects.