The clock as a focus of selective attention in those with primary insomnia: an experimental study using a modified Posner paradigm.

Espie and colleagues [(2006). The attention-intention-effort pathway in the development of psychophysiological insomnia: a theoretical review. Sleep Medicine Reviews, 10, 215-245] propose a route into psychophysiological insomnia along the attention-intention-effort pathway which focuses on the inhibition of sleep-wake automaticity. A contributing factor to this is selective attention to sleep (alongside explicit intention to sleep and effort in the sleep engagement process). Following on from previous work on selective attention to sleep [Marchetti, L. M., Biello, S. M., Broomfield, N. M., MacMahon, K. M. A., & Espie, C. A. (2006). Who is pre-occupied with sleep?. A comparison of attention bias in people with psychphysiological insomnia, delayed sleep phase syndrome and good sleepers using the induced change blindness paradigm. Journal of Sleep Research, 15, 212-221; MacMahon, K., Broomfield, N., Macphee, L., & Espie, C. A. (2006). Attention bias for sleep related stimuli in primary insomnia and delayed sleep phase syndrome using the dot-probe task. Sleep, 29, 11] and considering the importance of monitoring both internal and external cues in the maintenance of insomnia, as highlighted in the cognitive model of insomnia [Harvey, A. G. (2002). A cognitive model of insomnia. Behaviour Research and Therapy, 40, 869-893], a cognitive probe task was employed to investigate further the role of the clock as a focus of selective attention in those with primary insomnia. A 2 x 2 between participants design comparing reaction time of individuals with primary insomnia (n=22) and normal sleepers (n=22) on a modified Posner paradigm. Responses obtained from a computer task presenting times which fall within a normal sleep period were analysed. Individuals with primary insomnia demonstrated delayed disengagement to the clock (F(1,84)=6.9, p<0.05) which is taken as further support for previous research demonstrating that individuals with primary insomnia exhibit an attentional bias to sleep related stimuli. These results lend support to the attention-intention-effort model (Espie et al., 2006) and the cognitive model (Harvey, 2002) both of which recognise the importance of selective attention towards salient stimuli in the maintenance of insomnia. Possible clinical implications of attentional bias to sleep as a marker of psychopathology progression and treatment efficacy are discussed.