I've been using my instinct solar for a while now with literally no problems at all...
Now all of a sudden (I believe after 14.20 was installed) I started getting notifications in the middle of the night even though I can look at my normal bedtime/wake up and they are correct, and in in sounds and notifications in connect, it says "Do not disturb during sleep" is on.
I've tried setting times to times that are one minute off, and toggling the setting do not disturb during sleep, in hopes re-setting the settings would cause the watch to stop notifying me in the middle of the night to no avail.
My wife also has the same watch, and noticed the same thing that seems to have started happening in the last couple weeks.