Disturbed sleep: linking allergic rhinitis, mood and suicidal behavior.

Allergic inflammation is associated with mood disorders, exacerbation of depression, and suicidal behavior. Mediators of inflammation modulate sleep , with Th1 cytokines promoting NREM sleep and increasing sleepiness and Th2 cytokines (produced during allergic inflammation) impairing sleep. As sleep impairment is a rapidly modifiable suicide risk factor strongly associated with mood disorders, we review the literature leading to the hypothesis that allergic rhinitis leads to mood and anxiety disorders and an increased risk of suicide via sleep impairment. Specifically, allergic rhinitis can impair sleep through mechanical (obstructive) and molecular (cytokine production) processes. The high prevalence of mood and anxiety disorders and allergy, the nonabating suicide incidence, the currently available treatment modalities to treat sleep impairment and the need for novel therapeutic targets for mood and anxiety disorders, justify multilevel efforts to explore disturbance of sleep as a pathophysiological link.