I know there are the tags to attach to a new sleep tracking session, but it might be useful to have a more direct way of getting additional data that could effect ongoing sleep patterns, by prompting a short survey when activating sleep tracking.
Potentially questions could be customisable and the results could be analysed along with other sleep data. For example for people who drink coffee, it could ask when we last had a coffee, or a beer, or we ate or how stressed we feel, and use that to show the impact of those things on our sleep.
It would also make for some fairly useful scientific data on a larger scale.