A paper published in 2000 compared outcomes from treatments that combined the sleep medication estazolam with one of three non-pharmacological treatments: muscle relaxation, guided imagery, or sleep education. Participants were given four weeks of active treatment, after which they stopped taking the medication. The researchers found significant improvements in self-reported measures of sleep time, sleep efficiency, and wakefulness in the guided imagery and muscle relaxation groups, while the group that received sleep education only showed improvement in time spent asleep. At a six-month follow-up, all three groups showed significant improvement in all measures, as well as improvements in mood and daytime alertness.
In a 2002 study from the University of Oxford, insomnia patients were given image-related training to reduce unwanted cognitive activity and help them fall asleep faster. 41 people participated. Some were given no instructions, some were told to distract themselves with imagery, and some were told to distract themselves but not given any further details. Notable improvements were reported for those who distracted themselves with imagery. This option was thought to be the best because the specificity of the task made it easier for the patients to focus their attention.
The following year, another Oxford study investigated the number and types of images that insomniacs and good sleepers visualized before sleep. People with insomnia were found to visualize fewer images overall but to have higher numbers of unpleasant images and images relating to sleep, with the number of unpleasant images being directly correlated to the time it took them to fall asleep. These results suggest that adding additional images - especially pleasant, soothing images - could help normalize sleep patterns.