Table 5:

Self-reported Barriers to Research Participation and Strategies Used to Retain Participants with Drop-out Potential

	Self-reported participant barriers	Number of participants with this barrier	% Participants with this barrier	Strategies used to combat this barrier
Teen Sleep Study
	Emotional burden	1	0.01	3
	Time constraints	6	0.03	1, 2, 4, 6
	Found treatment unhelpful	4	0.02	3, 6
	Unknown	16	9.09	n/a
Community Sleep Study
	Homelessness and/or housing instability	4	3.33	2, 3, 4, 5, 6
	Family illness	3	2.48	3, 5, 6
	Physical health issue (e.g. surgery, chronic pain, cancer)	9	7.44	1, 2, 3, 4, 6
	Mental health issue (e.g. psychiatric hospitalization, decompensation, relapse, paranoia, avolition, etc.)	22	18.18	2, 3, 4, 5, 6
	Transportation	12	9.92	1, 2
	Scheduling conflicts (e.g. with work, school, family, children)	15	12.40	1, 2, 4, 6
	Difficulty with treatment (e.g. unwilling to change, disliked it, too much work)	10	8.26	3, 4, 6
	Lack of interest after placement in UC-DT	4	3.31	3, 4, 5, 6
	Moved away	6	4.96	1, 2, 4, 5, 6
	Passed away	3	2.48	n/a
	Unknown	2	1.65	n/a

Note. Participants were considered potential drop-outs if they appreciably delayed treatment or assessment, paused treatment for an extended time, fell out of touch with our team for a period, or expressed desire at any point to drop out of the study