More than just bad dreams: The nightmare disorder

Written by: Pierre-Olivier Gaudreault, PhD. Psychologist specialized in sleep medicine at HALEO Clinic.

Published on: May 24, 2024 | Reading time: 🕐 2m

Sleep is not only crucial for preparing our body to handle the upcoming tasks of our next wake period, but it is also important for processing emotions and consolidating what we learned the day before. This means that there are multiple very important processes happening in our brain at night. In other words, although our body is lying down and resting in our bed, our brain is far from being quiet. 

Dreaming is one of these processes that has been known to contribute to the regulation of whatever we learned and experienced emotionally during the previous day.1 

Allow me a quick side note. Some people may already be wondering whether dreaming is actually important since they never have the feeling that they dream at night. Although it is a common report, it has more to do with remembering the content of our dreams rather than the absence of this process. For instance, we are more likely to remember our dreams if we wake up from an episode of rapid eye movement (REM) sleep than the other sleep stages. 


Are nightmares just bad dreams?

Even if both nightmares and bad dreams have strong negative content, only a nightmare will wake you up during the night. Specifically, nightmares are upsetting and emotionally intense dreams that occur more often during the second part of the night, when we have the most of our REM sleep, the sleep stage associated with intense dreaming.2 

Nightmares can happen occasionally to anybody but only the frequent occurrences of nightmares that alter sleep and daytime functioning will be considered a nightmare disorder. 

Nightmare and mental health

Nightmares are universal, however their prevalence if significantly higher in individuals experiencing poor sleep quality, other diagnosed sleep disorders, depressive and anxiety symptoms, as well as post-traumatic stress disorder (PTSD). Reliving traumas through frequent and intense nightmares maintains PTSD symptoms and can even contribute to other sleep-related disorders such as insomnia. 


Do nightmares have a function?

We have yet to find to find a consensus among clinicians and researchers as to the specific utility of nightmare. So far, theories converge on the implications of these distressing dreams that perturb sleep in the regulation of emotions and memory processing. However, only some of our nightmares, may have this function. The frequent and intense nightmares observed in PTSD rather suggest a dysfunctional process that needs to be treated. 


How to treat Nightmare disorder?

Occasional nightmares might be distressing for some and wreak a night of sleep but is still considered a normal phenomenon. However, having frequent nightmares with significant impacts on your sleep, mood, and daily activities should be treated. At HALEO, we offer a specific psychotherapy program based on Image Rehearsal Therapy (IRT) and Cognitive-Behavioral Therapy for Insomnia (CBT-I) which is considered the best practice to treat nightmare disorder.4 

Other strategies can be used to limit the frequency of nightmares including: 

  • Asking your doctor and pharmacist for potential medication interactions and side effects that may cause nightmares. 
  • Being mindful of depressive and anxiety symptoms known to increase the risks of nightmares and seek professional help to treat any mental health conditions. 
  • Adopting an adequate sleep hygiene to help maintain good sleep quality. Important changes to our sleep routine such as sleep deprivation can alter the amount of REM sleep which could in turn increase risks of triggering nightmares. 

Finally, if you experience recurrent nightmares, unsatisfying sleep or chronic sleep issues, don’t hesitate to reach out to a sleep expert and to complete our 5-min online screener to get directed towards one or our scientifically proven sleep programs based on Cognitive-Behavioral Therapy for Insomnia (CBT-I). 


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  1. Cartwright, R., Luten, A., Young, M., Mercer, P., & Bears, M. (1998). Role of REM sleep and dream affect in overnight mood regulation: a study of normal volunteers. Psychiatry research, 81(1), 1–8.
  2. Stickgold, R., & Wamsley, E, J,. (2017). Why we dream. In Kryger, M. H., Roth, T., & Dement, W. C. (2017). Principles and practice of sleep medicine (Sixth edition). Elsevier.
  3. Germain A. (2013). Sleep disturbances as the hallmark of PTSD: where are we now?. The American journal of psychiatry, 170(4), 372–382.
  4.  Aurora, R. N., Zak, R. S., Auerbach, S. H., Casey, K. R., Chowdhuri, S., Karippot, A., Maganti, R. K., Ramar, K., Kristo, D. A., Bista, S. R., Lamm, C. I., Morgenthaler, T. I., Standards of Practice Committee, & American Academy of Sleep Medicine (2010). Best practice guide for the treatment of nightmare disorder in adults. Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine, 6(4), 389–401. 
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