Insomnia Appears to Be a Risk Factor for Anxiety and Other Psychiatric Disorders

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MIAMI -- People with anxiety often present with insomnia, but evidence suggests that untreated insomnia might precipitate anxiety disorders, according to a presentation at the annual conference of the Anxiety Disorders Association of America.

"We know as psychiatrists that anxiety disorders produce insomnia. But now we have evidence that insomnia is a risk factor for future psychiatric disorders, in particular, anxiety disorder," Dr. John W. Winkelman said.

Anxiety disorders are the most common psychiatric disorders, affecting more than 19 million Americans per year (N. Engl. J. Med. 2005;353:803-10). In addition, insomnia is the most common sleep disorder--an estimated 10%-15% of the general population has chronic insomnia (J. Clin. Psychiatry 2005;66[Suppl. 9]:14-7).

"By no other mechanism, these would have a significant overlap, but it's not just coincidence," said Dr. Winkelman of the Sleep Health Center, Brigham and Women's Hospital, Boston.

"Often, patients with insomnia are referred to us by a primary care provider with the assumption that there is a psychiatric disorder, but 60% do not have one," Dr. Winkelman said. "But if they do, anxiety disorders are the most common."

Differential diagnosis between insomnia and anxiety can be challenging because of substantial overlap in presenting symptoms. Worry, agitation, irritability, loss of appetite, impaired concentration, loss of interest, sleep disturbance, hopelessness, and fatigue are examples. These shared signs "might tell us something about the underlying physiology," he said.

Insomnia is a presenting symptom of anxiety disorders (Clin. Ther. 2000;22[Suppl A]:A3-19). Insomnia can also be a side effect of anxiety treatment or a residual symptom after treatment (Biol. Psychiatry 1995;37:85-98). Both subjective and objective studies in generalized anxiety disorder (GAD) document increased sleep latency, decreased sleep efficiency, and decreased total sleep time, he said.

"In PTSD, things get even uglier," he said. …