Dispositional mindfulness, insomnia, sleep quality and dysfunctional sleep beliefs in post-treatment cancer patients

• Dispositional mindfulness has been conceptualized as having distinct ‘facets’.
• ‘Acting with awareness’ was related to better sleep quality and psychological status.
• ‘Non-judging’ was associated with fewer dysfunctional beliefs and attitudes about sleep.
• ‘Non-reacting’ was related to less sleep difficulty and mood disturbance.
• Mindfulness did not moderate associations between sleep and psychological outcomes.

Dispositional mindfulness, or the tendency to be more mindful in daily life, has been associated with better psychological functioning and reduced overall distress. This study investigated the degree to which dispositional mindfulness was associated with sleep disturbances in cancer patients with insomnia. Further, we examined whether levels of mindfulness moderated the relationship between stress levels, mood disturbance, insomnia severity, sleep quality and dysfunctional sleep beliefs. Participants (N = 111) were adults who had been previously treated for cancer and currently met diagnostic criteria for insomnia. Higher levels of acting with awareness, non-judging and non-reacting were associated with better sleep and psychological outcomes. Despite these significant associations, mindfulness facets did not significantly moderate the relationship between stress, mood and sleep outcomes. This negative finding raises the possibility that increased mindfulness may not act directly to improve psychological outcomes, but rather through a series of other cognitive and affective changes. Our results emphasize the importance of addressing mood symptoms and stress appraisals as predictors of sleep disturbance in cancer patients.