Pre-sleep imagery under the microscope: a comparison of patients with insomnia and good sleepers

Abstract

During the pre-sleep period and in the natural home environment patients with insomnia ( N=20) and good sleepers ( N=20) were asked to record when an image came to mind by pressing a handheld counter. They then provided an oral description of the image and indicated whether the image was ‘pleasant’, ‘unpleasant’, or ‘neutral’ (responses captured via a voice-activated tape recorder). Subjective and objective (actigraphy) estimates of sleep-onset latency (SOL) were recorded. On both the handheld counter and the audiotape recording, participants with insomnia reported fewer images than the good sleepers. The insomnia group had a higher percentage of unpleasant images compared to good sleepers. For the insomnia group, but not the good sleeper group, there was a positive correlation between unpleasant images and subjective SOL. The insomnia group experienced more images regarding ‘intimate relationships’ and ‘sleep’ and fewer regarding ‘random/non-connected topics’ compared to the good sleeper group. The results are discussed with reference to proposals made by Borkovec, Ray and Stöber (Cognitive Ther. Res., 22, (1998) 561) in the context of generalised anxiety disorder (GAD).