Sleep disorders are potential symptoms of almost every psychiatric illness. Psychiatrists always inquire about sleep behavior when making a diagnosis. (indeed, even in ancient times sleep was part of the treatment regimen for psychiatric disorders.) Sleep quality is almost a barometer of mental health. If you are sleeping well over an extended period of time, you are less likely to have a mental illness. This is an oversimplification, of course, and only a doctor can really make a diagnosis of mental illness, but people who sleep well rarely have psychiatric problems.
The National Institutes of Health estimate that 26% of American adults have some sort of mental illness at one point over the course of a year. The severity and duration can vary widely, and it is a much small percentage that is under medical treatment.
It is difficult to make assessments, but some observers estimate 40% of patients who seek medical help for sleeping problems have a psychiatric condition.
Poor sleep can also contribute to the development or prolongation of mental illness. It’s both a symptom and a cause. And inadequate sleep can make it difficult to cope with mental problems.
Not enough sleep can make depression and schizophrenia worse. Sleep problems and mental illness are co-morbid,
People with mental illness often report sleeptime experienced as "non-restorative sleep" – this can be particularly frustrating as the individuals feel like there is no relief from their discomfort.
Sleep disorders are co-morbid with many other illnesses; the most common co-morbidities with insomnia are mental illnesses. It's estimated that 40% of insomnia patients and over 45% of hypersomnia patients have a psychiatric condition.
A Norwegian study recently concluded that the sleep disorders in mentally ill patients should be considered a stand-along problem deserving treatment rather than just an epiphenomenon of the mental disorder.
Often treating the mental illness makes insomnia go away. This is particularly true in cases of mild depression (dysthymia) which is very common (3.3 million Americans) and which often results in troubled sleep. Many people find their insomnia disappears quickly when they start taking antidepressant medication.
Bipolar disorder, which strikes over 5 million Americans, includes among its most visible symptoms wide swings in sleep and waking. Hypersomnia is a symptom part of the time and people also go long periods without sleeping and without feeling the subjective need for sleep.
Even apnea, where the proximate disorder is not in the brain but in the respiratory system, is linked with depression. Apnea and depression provide an illustrative case study of how mental illness and sleep disorders can be connected. Nobody thinks depression causes, to any appreciable extent, apnea. The cause runs in the other direction. The poor sleep apnea patients experience makes their quality of life worse and makes it more likely they will get depression.
Treating the apnea with a CPAP machine can make the depression go away sometime. This is a win-win proposition: Apnea is relieved and depression is mitigated without the use of psychiatric drugs.
This is a big general statement, but we are going to make it: people with mood disorders and anxiety disorders have disturbed sleep. If they are not chronic insomnias, their insomnia flares up with their mental disorders.
Other common mental illnesses include:
Disturbed sleep has long been known as a symptom of schizophrenia, but although poor sleep degrades the quality of life for these patients, scientists trying to figure out this mental illness have largely ignored the sleep problems. Treating doctors may prescribe insomnia medication or count on the medication aimed at the schizophrenia to address sleeplessness.
British researchers looked at mice with defects in the SNAP25 gene (which is known to be linked to schizophrenia) and found these mice were unable to adjust to external circadian cues. Whether it was light or dark had little effect on their sleep patterns, in contrast with other mice whose bodies adjusted to the external environment. The scientists found the normal connections between the suprachiasmatic nucleus and the rest of the body were not functioning normally. If this is true in humans, you could look at schizophrenia as a circadian disorder. Cardiovascular disease and obesity are more common in people with chronic circadian disorders and also in people with schizophrenia.
The first generation of antipsychotics used to treat schizophrenia had no universal effect on sleep architecture, but the later generation of so-called atypical antipsychotics including clozapine, olanzapine, and quetiapine have observable positive effects on sleep. Schizophrenic patients who take them sleep longer. Some drugs increase the length of slow-wave sleep, and some increase REM latency, similar to the effect of SSRI drugs on people with depression. When drug treatment is halted, the sleep benefits disappear. There are reports that these atypical antipsychotics seem to cause some sleep disorders (sleep walking, sleep-related breathing disorders, night-eating syndrome, and restless legs syndrome) but there is not a general effect that can be attributed to them.
Chronic health problems and chronic psychiatric problems are co-morbid as well as short-term sleep difficulties and short-term mental illness. Further, this correlation extends across patient demographics: race, sex, and age,
Even when the mood change doesn’t enough to merit depression, insomnia is associated with sadness. Researchers have followed groups of insomnias in longitudinal studies that stretch over years. They consistently find having insomnia increase the risk of later development of mental illness. The relative risk is on the order of 5, although it varies from study to study. That means people with insomnia are five times more likely to develop mental illness than those without insomnia. Some studies – but not all – have found insomniacs are at greater risk for developing anxiety or drug abuse.
People without mental illness have substantially lower rates of insomnia. It’s a striking enough difference that nobody doubts the tie between sleep disorders and mental illness any more.
The exacerbation of each other make mental illness and insomnia together a classic negative feedback loop, and once they get started, push the patient in a downward spiral. This makes treatment difficult.
A University of Michigan study found a strong correlation between insomnia and suicide. The technical term is co-morbidity. It is not clear whether insomnia is so irritating that it contributes to the person's suicidal tendencies or the mental illness that lies behind the suicide has insomnia as a symptom. Or there could be no cause-and-effect, but a more complex relationship.
The good news is that the overlap of mood and anxiety disorders with insomnia means doctors can often treat multiple symptoms at once. Solve one problem and the other goes away or at least diminishes. Of course there is a wide range of situations and doctors assess each patient separately. Some treatment plans may involve simultaneous treatment of the mental illness and the insomnia with separate modalities. Or the patient may be given medication for the mental disorder and a talk therapy that includes cognitive behavior therapy to address sleep issues.
Insufficient sleep increases the risk of the mental illness coming back, so the patient and doctor must take extra care in these situations to avoid a relapse of insomnia which could spark another downward spiral.
Antidepressant medications are often used to treat insomnia: amitriptyline, trazodone, or mirtazapine are known as sedating antidepressants, and the more common SSRI drugs in use today are employed for patients with sleep disorders, too. Some patients react to antidepressant medication by becoming more active and energetic, making it in some way more difficult to sleep (sleep onset insomnia), even as the relief of the depression alleviated sleep maintenance insomnia. Doctors sometimes give these patients both an antidepressant medicine and a hypnotic.
The federal government puts the center of its sleep research activity – the National Center for Sleep Disorders Research – in the National Blood, Heart, and Lung Institute. It could be argued that a more appropriate place is the National Institute of Mental Health.