Background: Our view is that sleep disturbance may be a contributory causal factor in the development and maintenance of psychotic experiences. A recent series of randomized controlled intervention studies has shown that cognitive-behavioural approaches can improve sleep in people with psychotic experiences. However, the effects of psychological intervention for improving sleep have not been evaluated in young people at ultra-high risk of psychosis. Improving sleep might prevent later transition to a mental health disorder. Aims: To assess the feasibility and acceptability of an intervention targeting sleep disturbance in young people at ultra-high risk of psychosis. Method: Patients were sought from NHS mental health services. Twelve young people at ultra-high risk of psychosis with sleep problems were offered an eight-session adapted CBT intervention for sleep problems. The core treatment techniques were stimulus control, circadian realignment, and regulating day-time activity. Participants were assessed before and after treatment and at a one month follow-up. Results: All eligible patients referred to the study agreed to take part. Eleven patients completed the intervention, and one patient withdrew after two sessions. Of those who completed treatment, the attendance rate was 89% and an average of 7.6 sessions (SD = 0.5) were attended. There were large effect size improvements in sleep. Post-treatment, six patients fell below the recommended cut-off for clinical insomnia. There were also improvements in negative affect and psychotic experiences. Conclusion: This uncontrolled feasibility study indicates that treating sleep problems in young people at ultra-high of psychosis is feasible, acceptable, and may be associated with clinical benefits.