Table 2.

Themes, subthemes, and illustrative quotes for each theme that emerged in the thematic analysis.

Theme	Subtheme	Examples
Content	Sleep information	“A sleep calculator. So, depending on age and things, when you should go to bed or when you should wake up.” “It would have lots of different information and ideas and strategies.” “It could have fun sort of facts like if it says you get this amount of sleep, it improves your actual mood, your awareness, your reflexes.”
	Sleep diary	“I would do it 5 times a week it’s just at the weekend because you don’t really know when you wake up.” “...cause with the tracking, I might not do it as soon as I wake up but maybe once I leave the house when I’m like on the school bus.”
Functionality	Gamification	“I think it’s good that you can unlock levels...it encourages you to use the app.” “That’s good for young people as young people want to play games.”
	Flexibility	“You could have a short training session or a long one.” “I’m not that keen on the long and short version idea, I think it would be better to say, there are this many questions in the session and it will take approximately this amount of time and when you have the time you sit down and do that.”
	Personalization	“...different types of information for people with different sleeping problems - something like “Hi [name]” or something related to you.”
	Reminders and notifications	“If it were important...asking “Have you filled in your data yet?” I’d do it, it’s not annoying.” “An option that we can swipe across and snooze it so that you can set it again later.” “Notifications I just ignore in general.”
	Accelerometer	“A lot of parents make you sleep with your phones outside of your bedrooms so they wouldn’t want you to sleep with your phone under your pillow.” “I would actually be really interested...so you can tell what helped you sleep.”
	Extra features	“A social media thing, so you could...post a message asking for help.” “...kind of like Siri, so you would ask her like, questions about your sleeping, and she would give you a list of options or something.”
Accessibility and user experience	Trust	“There’s a lot of dodgy app makers but if it’s some trustworthy - like you guys [Black Dog Institute], then I would [trust it].” “The logo is really important.”
	Privacy	“I feel secure, I like the password.” “I think the “Sleep Ninja” is really good because you can say it’s a game.”
	Data security and confidentiality	“I usually put in fake details.” “Sometimes I don’t like, trust the app. Coz I could do my own thing and they could steal my identity, for all I know.”
	Data usage and Internet coverage	“If I’m gonna download an app that requires a lot (of data) I’ll wait awhile.” “I don’t really use Internet that much. I restrict my apps.”
	Cost	“Okay um 50/50 an app costing something is not necessarily going to turn you off.” “I’m just happy to tolerate some ads and stay with the free version.”
	Age-appropriateness	“I think it’s good for people our age group...it’s very simple to use.”
	Look and feel	“It just has to have a good logo.” “Cartoons are good because they’re just kind of easy to recognize.” “...it needs to have a good layout and easy to navigate.”
	Predicted likelihood of using Sleep Ninja	“I would definitely download it and I would do it for a couple of days but I don’t know if I’d get sick of it.”
Obstacles to sleep	Technology use	“When you’re using Instagram or Facebook you’re kinda going quickly so if you’re in that mindset before going to sleep you can’t really relax completely.”
	Cognitive and emotional factors	“Sometimes I overthink and then I can’t get to sleep because I’m overthinking.” “...if I’m not getting to sleep, I start stressing that I can’t get to sleep because I worry that the next day I’m going to be tired and I keep on thinking about things and I worry.”
	Environmental factors	“...even if the door is slightly open and there is a little bit of light coming in, it’s also disrupting. And if I’m sleeping in a spot that’s not my usual bed.”
	School commitments	“...with group assignments we often have to do all-nighters and things.”
General phone habits		“I always carry my phone with me.” “I would feel like half empty [if I forgot my phone]. Coz, I would be thinking the whole time like, has someone messaged me?” “I’m not allowed to sleep with my phone in my room but I hide it.”
Bedtime habits		“I sometimes put my phone on aeroplane mode right before I go to bed.” “I usually do something that doesn’t help me go to sleep. I will go through my Twitter timeline and my YouTube feed...does keep me awake for a long time.”
Attitudes toward apps for health		“If there was something you had a problem with, you would want to go see someone but if it was something you were more curious about...like, I wonder if doing this affects me, you would get an app.” “I reckon if I did have a sleeping problem, I would be interested.”
Motivation for changing sleep habits		“I would do it, if, in the long term it would affect me in a positive way.” “I sleep well, well...not well, but I don’t really care about how I sleep, like I’m not a really bad sleeper but I don’t really mind.”