Nightmares can cause difficulty both to sleep and to our waking lives. Intense and distressing dreams often lead to waking at night and can create anxiety about returning to sleep. Nightmares also can have an impact on our moods the next morning, bringing anxiety and difficult emotions into the waking day. New research suggests that nightmares also have an aggravating effect on symptoms of depression, and in combination with insomnia may significantly exacerbate the severity of the mood disorder.
Researchers at Japan's Tokyo Medical University investigated the influence of nightmares on depression, both independently and in conjunction with insomnia. They found the presence of nightmares associated with aggravating effects on depression. They also learned that the joint presence of insomnia with nightmares had a significant effect on the severity of depression.
The study included 2,822 adults, all of whom were residents of a rural community in Japan. The average age of participants was 57. All participants responded to questionnaires regarding their sleep habits and sleep quality, as well as the presence of nightmares and their frequency. Participants also answered questions to evaluate the presence and severity of depression. Researchers' findings indicate that while both insomnia and nightmares influence depression, when they exist together their influence is particularly strong:
• Among the 2,822 adults in the study, 25.5 percent had insomnia.
• Of the total participants, 4.6 percent experienced nightmares one or more times per week.
• Nightmares were present much more often in people with insomnia than without. Among participants with insomnia, 70.7 percent also had nightmares, compared to 29.3 percent of participants without insomnia.
• Both insomnia and nightmares were linked individually to higher scores for depression, indicating more severe versions of the disorder.
• When insomnia and nightmares were both present, depression severity was rated even higher, indicating a compounding effect of the two sleep problems.
Interestingly, researchers found that the severity of depression was no worse among people who experienced nightmares three or more times in a week, compared to people who reported having nightmares one or two times weekly. This suggests that it is the presence of nightmares at an even modest degree, as opposed to the frequency of the nightmares, which may exacerbate depression.
Nightmares remain a relatively little understood phenomenon of sleep. But we have seen recent research that explores the neurological activity that takes place during disturbed dreaming, as well as investigations of the possible neurocognitive functions behind nightmares and bad dreams.
A recent study explored the often provocative and frightening content of disturbed dreams, as a way to further understand the purpose and the impact that these dreams have on our sleep and our waking lives. There is also a body of research that links the presence of nightmares to more severe depression and anxiety as well as to increased risk of suicide among people with depression:
• Among patients with major depression, nightmares may increase the likelihood of suicide attempts, according to research. In a group of people diagnosed with major depression, those who had attempted suicide one or more times had significantly higher rates of both nightmares and insomnia.
• Another study examining the link between major depression and nightmares found that patients with major depression who reported frequent nightmares were more likely to be identified as suicidal than people who suffered major depression not accompanied by nightmares. Women with major depression and nightmares were found to be at particular risk for suicidal tendencies.
• Other research also indicates women may be especially vulnerable to the influence of nightmares on depression. Scientists in Estonia studied anxiety and depression in relation to sleep problems among a group of medical students. They found among female students an association between the presence of nightmares and both anxiety and depression. No similar link between nightmares, anxiety, and depression was found in male students.
We have a great deal more to learn about nightmares and other forms of disturbed dreaming, and how they may complicate and heighten the risk of mood disorders such as depression. We've seen some important recent breakthroughs in treatment for depression that highlight how important a role sleep play in the course of depressive illness, and in its treatment:
• Recent research indicates that a drug used to treat the sleep disorder narcolepsy may have benefits for depression when used in combination with other medication. Modafinil, a drug used to treat narcolepsy, has shown promise in easing the severity of depression when used in conjunction with anti-depressant medication. This treatment combination also raised rates of remission from depression.
• A federal study on sleep and depression -- the first of several to be released on the topic -- found that treating insomnia in people with depression may as much as double the likelihood of recovery from the mood disorder.
Achieving a deeper understanding of sleep and its impact on mental health may soon be changing the way we treat depression and other mood disorders. Just as sleep is now recognized not only as a symptom of depression but also a contributor to the illness, we may also find that nightmares exist as both a consequence of depression and a factor in its development.
Recognizing the specific risks that the presence of nightmares may pose -- on their own and in combination with other symptoms of disrupted sleep -- can help better identify people who are at higher risk for more aggravated and more dangerous forms of depression. And that could bring us one important step closer to getting people the help they need.
Michael J. Breus, PhD
The Sleep Doctor™