Treatment of insomnia is largely inadequate, according to sleep researchers. More than 30% of adults in industrialized countries suffer from occasional insomnia; another 12% have chronic insomnia. Some primary care physicians are prescribing sedating antidepressants or antihistamines to these patients. Guidelines recommend use of these agents for a maximum of 14 weeks, but some patients are prescribed medications for at least a year, according to the director of the sleep disorder and research center at Henry Ford Hospital, Detroit. Tricyclic antidepressants are inappropriate for insomnia patients who are not suffering from depression. In most cases, chronic insomnia is a symptom of an underlying problem that requires a specific diagnosis.