The validity of the Dutch Sleep Disorders Questionnaire (SDQ)

The Sleep Disorders Questionnaire (SDQ) is a 176-item questionnaire designed to diagnose the presence of common sleep disorders. This study set out to assess the validity of a Dutch translation of the SDQ. 125 physician-referred patients (aged 16-82 yrs) with several sleep complaints and 20 controls filled out the questionnaire. A cluster analysis of these scores revealed the following clusters: healthy, depression, insomnia, narcolepsy, and apnea. The cluster classification proved correct for 67% of the Ss, as determined on the basis of polysomnography. These results show that the Dutch SDQ is a reasonably valid instrument for diagnosing sleep disorders.