Eur Arch Psychiatr Neurol Sci (1989) 239:113-124 Psychiatry Neurological Sciences © Springer-Verlag 1989 The Zurich Study VIII. Insomnia: Association with Depression, Anxiety, Somatic Syndromes, and Course of Insomnia* Margarete Vollrath, WernerWicki, and Jules Angst Psychiatric University Hospital, Zurich, Research Department, P.O.Box 68, CH-8029 Zurich, Switzerland Summary. The association of three subtypes of in- somnia with psychic and functional syndromes, and the course of insomnia over 7 years were examined in a Swiss cohort of young adults interviewed three times. Specific associations were found between re- peated brief insomnia (RBI) and recurrent brief de- pression (RBD). Continued insomnia (CI) was asso- ciated with major depression. All three subtypes of insomnia were associated with anxiety disorders; 52% of insomniacs were free of concurrent anxiety and depression. Insomnia - especially RBI and CI - was also associated with a number of functional com- plaints, but not with the consumption of alcohol, medicine, or illegal drugs. Insomniacs with RBI and occasional insomnia (OI) experienced more life events and interpersonal conflicts than controls. These findings support the subdivision of insomnia into different subtypes. The longitudinal analysis showed that insomnia tends to reoccur. For subjects with insomnia either at age 21 or 23 years, there was a higher risk of further insomnia at follow-ups. The specific subtype of insomnia at the first occurrence was not predictive for the outcome: all subtypes of in- somnia enhance the risk of relapses in a similar way. Insomnia at age 21 is no precursor of the first onset of a depressive or anxiety disorder within a 2-year fol- low-up. With respect to the course of insomnia over 7 years, the subtypes did not differentiate. Key words: Insomnia - Epidemiology - Anxiety - Depression - Course - Follow-up * Project supported by grant 3.948.0.85 from the Swiss Na- tional Science Foundation Offprint requests to: M. Vollrath Introduction In a first paper (Angst et al. 1989a), three subtypes of insomnia were described: continued insomnia (CI), repeated brief insomnia (RBI) and occasional insom- nia (OI). In this second paper we analyze the associa- tion of these subtypes of insomnia with other com- plaints and describe their course over 7 years in a cohort of young adults from the Canton of Zurich. There is much clinical- and research-based evi- dence that insomnia is strongly associated with both anxiety and depression. Indeed, insomnia is an im- portant item in all instruments measuring anxiety or depression and, for instance, a criterion symptom for the diagnosis of major depression. Elevated scores for anxiety and depression scales have not only been found in samples of insomnia patients (Kales et al. 1983; ASDC 1979), but also for insomniacs in healthy populations, as for instance in nurses (Tsoi and Tay 1986) and in epidemiological samples from the gen- eral population (Mellinger et al. 1985). There is also ample evidence that insomnia can be linked to physical disorders. Mellinger et al. (1985) found in their sample from the general population that serious cases of insomnia tend to complain more often about multiple, otherwise unspecified health problems. An epidemiological study of 3201 Swedish men 30-69 years of age reported higher prevalence rates of insomnia among hypertensives, among men with obstructive pulmonary disease, with rheumatic disease, and with obesity (Gislason and Almqvist 1987). Furthermore, it is known from practical work with patients that insomnia frequently accompanies functional complaints and pains. The use of drugs, alcohol, and caffeine can cause and maintain sleep disturbances. In a study on 279