When initiating sleep tracking from the phone, you must confirm a dialog on the watch, asking you if you want to launch Sleep. To initiate the connection between the watch and the phone, we need to launch the Sleep app on the watch - but the way Garmin designed it, it is not possible to programmatically launch an app on the watch without asking the user for consent.
This is a companion discussion topic for the original entry at https://sleep.urbandroid.org/docs/faqs/garmin_start_dialog.html