Insomnia is frequently associated with physical and mental health disorders.1–4 Insomnia is a risk factor for the development of depression,12 and depression is a risk factor in the persistence of insomnia.5,7,11 As far as the association of chronic insomnia with the second most common sleep disorder (SDB), the findings have been mixed. Some but not all investigators have suggested that SDB is associated with chronic insomnia.13,14 However, no longitudinal study to date has examined whether SDB is a risk factor for the persistence of insomnia.