Sleep disturbances are common in psychiatric disorders. It has been established that 4.4% to 20% of the general population suffers from a major depressive disorder, which is frequently associated with a dysregulation of normal sleep-wake mechanisms (45). Disturbances of circadian rhythms are a cardinal feature of psychiatric dysfunctions, including major depressive disorder, suggesting that biological clocks may play a role in their pathophysiology. In addition, the habit of sleeping at a time that is out of phase with the body's other biological rhythms is a common finding in depressed patients (45). Depression is associated with longer sleep latency, frequent and long awakenings, and/or early morning awakening associated with poor sleep satisfaction. Sleep disturbance associated with depression sometimes responds to treatment of the underlying depression. Some antidepressants, such as mirtazapine, directly improve sleep quality. Unfortunately, most antidepressants, including the selective serotonin reuptake inhibitors and duloxetine, have the side effect of insomnia. Adjunctive medication is often necessary to treat depression- or antidepressant-associated insomnia. The author discusses the evaluation and treatment of sleep disorders associated with depression.
• Sleep disorders are commonly associated with psychiatric disorders.
• A sleep complaint could be the heralding symptom of a psychiatric disorder.
• Insomnia can lead to depression and/or common causalities underlie both disorders.
• Prevention of sleep disturbance is best achieved by preventing the onset of depression.
Historical note and terminology
Sleep disturbance in depression has been described at least as far back as the ancient Greeks. Throughout history there have been great numbers of famous people who are known to have suffered from insomnia and depression. It is a well-known fact that for most of his life Winston Churchill suffered from insomnia and depression that persisted until old age. Churchill referred to this depressive state as his "black dog." The famous British mathematician, astronomer, and philosopher, Sir Isaac Newton, 1 of the leading pioneers of scientific discovery, was also known to have suffered from inability to sleep and depression.
Mood disorders, including depressive disorders and bipolar disorders, are commonly associated with sleep disturbances. Major depressive disorder or unipolar depression is diagnosed in people who have experienced 1 or more major depressive episodes. The essential feature of a major depressive episode is a period of at least 2 weeks during which there is depressed mood or a loss of interest in pleasure, together with at least 4 of the following symptoms: (1) weight gain or significant weight loss when not dieting; (2) insomnia or hypersomnia; (3) psychomotor agitation; (4) fatigue or loss of energy; (5) feelings of worthlessness or excessive or inappropriate guilt; (6) diminished ability to think or concentrate; (7) recurrent thoughts of death, suicidal ideation, or a specific plan to commit suicide. The Diagnostic and Statistical Manual of Mental Disorders (DSM-V) criteria for major depressive episode include insomnia or hypersomnia nearly every day.
Insomnia is seen in 80% to 85% of patients with depression. A systematic review suggested insomnia is bidirectionally related to anxiety and depression (02). People with insomnia have significantly higher levels of depression than people not having insomnia; increased insomnia frequency and increased numbers of awakenings are related to increased depression and anxiety, which is also among adolescents and university students (49).
Less frequently, in about 15% to 20% of cases, patients with depression complain of hypersomnia, with prolonged sleep episodes at night or increased daytime sleepiness and fatigue.
Depression may be also associated with other sleep disturbances, such as restless legs syndrome, obstructive sleep apnea syndrome (36; 57), and narcolepsy (16; 01).