Table 1 Interview guide

Opening question

1. From the questionnaire we saw that you sleep 8h a night on average. Do you think this is enough? How many hours do you think you should sleep to get enough sleep?

2. What can you do to sleep well? What is good sleep hygiene?

Transition

3. How much do you think your peers sleep? How well do you think your peers sleep?

4. Why is it important to get enough and qualitative sleep?

Key questions part 1

5. What factors influence your sleep duration? = what actually makes you sleep enough or too little?

6. Would you like to change your sleep duration? And your sleep quality? How important would that be for you? Do you think you would be able to change it? Why or why not?

7. What do you think will change when you sleep more / better? Only advantages or also disadvantages?

8. What do you think you can do to change this?

9. What obstacles would there be to change this? What would make it difficult for you to change this? Think of personal obstacles, but also impeding factors in the environment (in your bedroom, house, street, influence of your family, …)

10. What could help you to tackle those obstacles (difficulties)?

Key questions part 2

11. Suppose we want to create some kind of intervention / health program / campaign that encourages you to sleep better and more, would you like to help develop this program?

(if necessary, indicate the concept of an intervention using an example of another intervention related to sport)

12. How would you like to make such a program completely by yourself / independent, together with a number of peers? Would you like that, would you find it interesting, useful, important?

13. If you are fully responsible for developing the program, this would not only mean inventing the program, but also carrying it out, evaluating it afterwards, … Is that something you could do? Or would you need help from certain people?

14. Do you think it necessary that you have such a big / important role? Why or why not?

15. How would you like to do this at school? E.g. Create such a program with a number of students from your class / year / school and then implement it at school? If not at school, where else?

16. Do you already have some ideas for a campaign?

Ending questions

17. From what has been said, what is most important to you? What do you think I should definitely remember from this conversation?

18. Is there anything else you want to say?