Table 1.

Summary of objectives and assessment measures

	Objectives	Outcome measures
Primary	Assess the feasibility and acceptability of a targeted sleep intervention to prevent psychosis and to establish key parameters for a future randomised controlled trial.	Number of patients identified, recruited, declined and retained.
		Number of referrals made per site, and per service type, per month.
		Service use as measured on the CSRI.
		Completion rate of each assessment measure, including wearable-technology devices. Time taken to complete each assessment.
		Location and attendance at treatment sessions; content covered in treatment sessions; feedback from qualitative interviews; treatment acceptability score (AARP).
		Service use data completeness, time taken to collect service use data.
Secondary	Gather data on clinical outcomes to provide a preliminary indication of the clinical effectiveness of a novel sleep intervention (SleepWell) in addition to usual care versus usual care alone in young people with sleep problems who are at ultra-high-risk of psychosis attending NHS mental health services	Sleep disturbance: ISI; Sleep-50 CRD; Sleep diary; Actigraphy; Fatigue. Attenuated psychotic experiences: CAARMS; SPEQ-H; R-GPTS; ČEFSA. Psychiatric symptoms: DASS-21; C-SSRS; DWQ; BCSS. Activity and social functioning: Time budget; WASA; Oxford Agoraphobic Avoidance Scale; actigraphy. Physical health: BMI; step-count; BESAA; PHQ15; MAP. Quality of life: QPR; ReQoL; EQ5D. Service use: CSRI; and medication. Participant ranking of clinical outcome variables.
Qualitative	To explore the acceptability of study procedures to service users.	Feedback from qualitative interviews.

AARP, Abbreviated Acceptabliity Rating Profile; BCSS, Brief Core Schema Scale; BESAA, Body Esteem Scale for Adults and Adolescents; CAARMS, Comprehensive Assessment of At-Risk-Mental States; CRD, Circadian Rhythm Disruption; CSRI, Client Service Receipt Inventory; C-SSRS, Columbia Suicide Severity Rating Scale; DASS-21, Depression, Anxiety, and Stress Scale; DWQ, Dunn Worry Questionnaire; ČEFSA, Černis Felt Sense of Anomaly Scale; ISI, Insomnia Severity Index; MAP, Maudsley Addiction Profile; NHS, National Health Service; PHQ15, Patient Health Questionnaire; QPR, Process of Recovery Questionniare; R-GPTS, Revised Green et al Paranoid Thoughts Scale; SPEQ-H, Specific Psychotic Experiences Questionnaire - Hallucinations subscale; WASA, Work and Social Adjustment Scale.