In short: Yes, but it's not ideal. If you have to play different roles (facilitator + decision maker or facilitator + participant) here a few tips to make it less painful:

• Introduce it well

• Mark the transitions

• Or swap the facilitator role throughout the sprint.

It's not perfect but it's okay

Obviously, separating roles makes your life much easier. But in practice, there are moments where you just have to juggle different roles. Maybe you don't have the money to hire an external facilitator. Or nobody else is trained to facilitate a design sprint within your organization.

To me, I wouldn't cancel a design sprint because you have to mix roles. I would just go with it even if it isn't perfect. The key is to make the best of the situation.

How to mix roles more easily?

Say it in the introduction

The first thing is to be very clear in the introduction of your design sprint that you have two roles during that design sprint. So that everybody knows you'll speak with two different hats or mindsets.

Mark role transitions

Whenever you share something, indicate which role you're speaking from. You can for example say:

In my role as a decision maker here is what I have to say: ...

You can even use physical hats of different colors for each role. Swap out the hats to visually signal you're changing roles.

Swap the facilitation role throughout the sprint

An alternative is to swap the roles among team members. This works better for facilitation than decision-making. To me, it's important that the decision maker stays consistent throughout the whole design sprint.

But the person who facilitates can change from exercise to exercise or half day to half day, allowing each person to participate fully at least in some parts of the process.