Pebble Time 2 does track your sleep well. You can see your data in the Pebble Health App.
The watch will also wake you up if you’re within 30 minutes of your alarm and you are in light sleep. Some people like this feature and others don’t. The science backs up this early wake-up, so I’m willing to give it the benefit of the doubt. I suggest you give it a try. You can always turn off the alarm.