The study sample consisted of 80 patients with primary
insomnia according to the criteria of DSM-IV [10] and 45
healthy controls. All patients were referred by their physicians
or were self-referred to one of the sleep laboratories at
the Departments of Psychiatry of the Universities of Freiburg
or Luebeck. Controls participated in different studies
and performed the PSQI additionally for this study. After a
thorough medical examination to rule out any somatic or
psychiatric disorder underlying sleep disturbances, the
patients had two nights of polysomnography in the sleep
laboratory including measurement of sleep apneas and
periodic leg movements