Depression and insomnia could lead to more frequent nightmares

Symptoms of depression and insomnia are the strongest predictors of frequent nightmares, according to the findings of a new study conducted by researchers at the University of Turku in Finland and the Finnish National Institute of Health and Welfare.

Frequent nightmares may lead to a fear of going to sleep or worry that each night will bring another nightmare.

The study, published in Sleep, aimed to both test whether factors previously associated with frequent nightmares could be reproduced in a large population sample and to examine whether any previously unreported associations exist.

This study shows a clear connection between well-being and nightmares. 

This is most evident in the connection between nightmares and depression, but also apparent in many other analyses involving nightmares and questions measuring life satisfaction and health.

The American Academy of Sleep Medicine define nightmares as "usually coherent visual dreams that seem real and get more disturbing as they unfold and cause you to wake up." Nightmares often involve imminent physical danger and can provoke a range of negative emotions including anxiety, terror, embarrassment and disgust.

For the study, the researchers analyzed data taken from two independent cross-sectional surveys of the Finnish adult population conducted in 2007 and 2012. Questionnaire data were available for 13,922 participants aged 25-74 years and included nightmare frequency along with other items related to overall health and lifestyle.

As part of the National FINRISK Study, participants were sent questionnaires in the post that were completed and returned to a local primary health care center. 

At the health care center, each participant underwent a health examination and had their questionnaires checked by a nurse.

A total of 3.9% of participants reported having frequent nightmares during the previous 30 days, compared with 45% reporting occasional nightmares and 50.6% reporting no nightmares at all.

Nightmares 'could function as early indicators of onset of depression'

The researchers found that 28.4% of participants with severe depressive symptoms reported experiencing frequent nightmares, as did 17.1% of participants with frequent insomnia.

After analyzing the data further and adjusting for potential confounders, the researchers concluded that the strongest independent risk factors for frequent nightmares were insomnia, exhaustion and "negative attitude toward the self" - a symptom of depression.

Additionally, a wide variety of factors related to psychological and physical well-being were associated with nightmare frequency with modest effect sizes. 

These factors included sex, age, self-reported impaired ability to work, low life satisfaction and frequent heavy use of alcohol.

Hence, nightmare frequency appears to have a strong connection with sleep and mood problems, but is also associated with a variety of measures of psychological and physical well-being.

The study is limited by its cross-sectional design, meaning that the researchers are unable to determine causality for their observations. However, the researchers believe their findings could provide the basis for future research.

It might be possible that nightmares could function as early indicators of onset of depression and therefore have previously untapped diagnostic value. Also, because nightmares, insomnia and depression often appear together, would it be possible to treat all of these problems with an intervention directed solely toward nightmares?

References:

1.  Nightmares: risk factors among the Finnish general adult population, Nils Sandman, et al., Sleep, http://dx.doi.org/10.5665/sleep.4560, abstract.
2.  American Academy of Sleep Medicine news release, accessed 7 April 2015 via EurekAlert.
3.  Additional source: American Academy of Sleep Medicine, Nightmares - overview, accessed 7 April 2015.