Melynda Casement and Leslie Swanson have recently published an interesting meta-analysis on imagery rehearsal therapy. Find the summary below, with thanks to Georgina Johnstone*.
Sleep problems are a central component of posttraumatic stress, both in children and adults. Difficulty maintaining sleep is reported by up to 91% of people with PTSD, with 72% experiencing nightmares.
Imagery rehearsal (IR) therapy is more and more used to overcome these sleep problems. Although not all versions of IR employ exactly the same techniques, they all have a cognitive behavioral orientation and include these three elements:
- Sleep education (see sleepeducation for tips)
- The writing of a dream narrative which includes the modification of a particular part of the nightmare, and
- Daily imaginal rehearsal of the modified narrative.
Some therapies also include direct exposure to the original nightmare (e.g., reading an account of it aloud to the therapist).
Casement and Swanson aimed to assess the merit of IR as an intervention for nightmares, sleep quality, and posttraumatic stress symptoms. Apart from the magnitude of the treatment effect, they were interested in potential differences between treatment protocols and labs.
Eligible studies were retrieved via bibliographic databases, reference lists, a recent qualitative review, and direct contact with authors. The search led to 13 studies that satisfied all quality and measurement criteria. The samples consisted of civilians, veterans and active duty military personnel. The studies used 8 different IR protocols.
The authors calculated effect sizes for pre-treatment versus post-treatment groups and experimental versus control groups, based on random effect models. To assess the influence of treatment methodology and sample characteristics, they used mixed effect models.
This is what they found: IR treatment improves sleep quality and reduces the frequency of nightmares across samples and treatment protocols. Interestingly, IR leads to large decreases in PTSD symptoms even though general PTSD symptoms are not a direct target of the treatment. The effect sizes were moderate to large and the results were sustained over 6 to 12 month follow-up assessments. The results also suggested that combining IR and CBT is more effective than IR alone for insomnia but this added effect does not appear for PTSD symptoms or nightmares.
The authors make one important caveat: only 5 of the 13 samples were randomized controlled trials, with only one study comparing IR with an active treatment control condition. The effect sizes in this latter study were small.
In short, the authors give these take-home messages regarding imagery rehearsal:
• IR improves nightmare frequency, sleep quality, and PTSD symptoms.
• The benefits of IR are sustained for 6 to 12 months following treatment completion.
• Direct comparisons of IR and established PTSD interventions are warranted.
Casement MD, & Swanson LM (2012). A meta-analysis of imagery rehearsal for post-trauma nightmares: effects on nightmare frequency, sleep quality, and posttraumatic stress. Clinical psychology review, 32, 566-74 PMID: 22819998
*Georgina is a research assistant at the Trauma Recovery lab.