The connection between amitriptyline and sleep is that amitriptyline increases levels of chemicals in such a way that often allows people to fall asleep more easily and stay asleep longer. Amitriptyline is a tricyclic antidepressant drug that is sometimes used as a sleeping aid for people with insomnia, or trouble sleeping. Using amitriptyline for insomnia is considered an "off-label" treatment. In other words, amitriptyline has not been specifically approved by the US Food and Drug Administration (FDA) to treat sleep disorders, but it is generally considered a safe course of treatment that is effective for at least some patients.
Like most antidepressants, amitriptyline works by increasing the level of certain chemicals in the brain responsible for producing feelings of happiness. In the case of amitriptyline, the chemicals, or neurotransmitters, effected are serotonin and norepinephrine. Tricyclic antidepressants like amitriptyline have largely been replaced by more modern drugs that produce similar results, but with fewer side effects.
Amitriptyline and sleep are related in that depression and insomnia often go hand in hand. The exact reasons for this are not known, but there is some evidence that increased wakefulness leads to more serotonin production. If this is the case, insomnia may be the body's way of treating depression on its own. Amitriptyline or other antidepressants may reduce the body's need to produce serotonin through wakefulness. Whatever the reason, some patients are able to take amitriptyline and sleep through the night more easily than if they had not taken it.
One reason amitriptyline may be preferred to other insomnia treatments is that it remains in the body longer than most over-the-counter sleep aids. Its half-life — the amount of time that it takes for half of the medicine to be processed in the body — is about 12 to 24 hours, as compared to anywhere from less than two hours to nine hours for similar medications. This makes amitriptyline a good option for people with early-waking insomnia, a condition in which the patient is usually able to fall asleep in a reasonable amount of time, but is unable to stay asleep.
On the other hand, the connection between amitriptyline and sleep is weak enough in some patients to be ineffective. It may also have side effects, such as dizziness or drowsiness in the morning. Patients seeking treatment for insomnia should discuss all potential risks and benefits with a doctor or pharmacist.