During my time at Fitbit I was able to launch several sleep features. I worked on all of these with a product designer, a product manager and a team of iOS, Android, backend, and QA engineers. You can read more about these features here.
While this feature seems small in the grand scheme of things, a lot of work went into the way we present sleep goals to our users. Those who don't get the recommended 7-9 hours should not be shamed when it's out of their control.
With sleep schedules we could use someone's own data to help them set a realistic goal and provide them with a schedule and reminder to help them reach that goal. Slowly over time the user can increase their sleep goal and ultimately get more much needed rest. This feature allowed us to make a much needed improvement on the sleep goal feature.
Sleep Insights is something that gets better with time. The more we know about the users patterns both sleep and active, the more helpful we can be when providing them with (ideally) actionable insights. We created a feedback mechanism for the insights testing that ultimately ended up shipping because the information we were getting from our testers was so valuable we wanted to get that from actual users. The newest addition to sleep insights has been the data from sleep stages. Having more granular data like that helps draw deeper, more personalized insights.