The connection between insomnia and multiple somatic diseases is well known. These psychiatric disorders are caused by, or may cause insomnia. The relationship between sleep quality and psychiatric disorders is predominantly analyzed using patients suffering from depression.
Insomnia is one of the well-known risk factors of depression. Simply put, people suffering from poor sleep quality are more prone to depression than people without sleep disorders. The results of a 12-month study of insomniacs showed they were almost forty times more likely to suffer from depression if the insomnia was present throughout the entire study, but only one and a half times more likely if the insomnia was cured within 12 months of the research, when compared to the control group consisting of people with no sleep problems.
The negative impact of insomnia on our life is not only a matter for today. The effects of insomnia in the present may cause depression in the future, even after many years. This was demonstrated in a lengthy study evaluating the risk of future depression in male medical students. After many years of having difficulties falling asleep, or even being unable to fall asleep due to the constant stress, students with sleep disorders were much more prone to depression in the future than their peers.
Insomnia is not only the main risk factor of depression; it also appears as the first symptom of a relapse. Insomnia precedes the first depressive episode in 41% of patients and precedes a relapse in 56,2%. Insomnia is also associated with anxiety disorders, but the connection is not as obvious as it is with depression.
Although many people believe insomnia is resolved once the underlying disorder is cured, depression, in many cases, is not that simple. Patients suffering from depression complain about chronic sleep disorders even when the psychiatric disease is cured. Patients with depression were more prone to complain about sleep problems than patients suffering only from sleep disturbances. However, once the acute phase of depression was resolved, insomnia was less severe. It is the sleep disturbances and chronic fatigue that are the most resistant to treatment for symptoms of depression.
Regardless of the connections between insomnia and psychiatric or somatic diseases, patients suffering from insomnia are said to have a poorer quality of life than those with no sleep problems. Their state of health is as bad as those suffering from severe somatic diseases or long lasting, serious depression.
All in all insomnia is not only a factor in increasing the risk of depression now or in the future, but also a chronic symptom in patients suffering from depression, even after resolution of mood problems.