Amitriptyline has sedative effects, which may improve sleep latency and sleep maintenance (it has a long half-life); it may also improve sleep indirectly by treating headache or mood disorders. The drug has been used off-label for treatment of insomnia for many years, but data from large controlled trials are lacking, and insomnia treatment guidelines do not recommend its use.2

Anticholinergic and antihistaminic adverse effects (e.g., urinary retention, constipation, dry mouth, blurred vision, orthostatic hypotension) are common with amitriptyline. Amitriptyline also can cause QT-interval prolongation and cardiac conduction delays. Chronic use of anticholinergic drugs has been associated with an increased risk of dementia and is not recommended for older patients.3

Amitriptyline doses used for treatment of insomnia are lower than the usual antidepressant doses (10-50 mg vs 100-300 mg) and may be better tolerated, but data are lacking.

The tricyclic antidepressant doxepin (Silenor, and generics) is FDA-approved for treatment of sleepmaintenance insomnia in low doses (3-6 mg, compared to 75-300 mg for depression).4 It has been shown to provide a hypnotic effect without causing anticholinergic and other typical tricyclic adverse effects and is generally preferred over amitriptyline and other antidepressants for such use.