Smart watch or those band type is really a good option. Before this, I don't have the habit to wear watch to bed too. But alarm sound always give me unpleasant wake up as I need to quickly set it off, worry it may affect others. When using h/p even worst, as I avoid having it too near me, I gotta run to another corner of the room to get it.

Now using smartwatch, it actually gently waking me up by vibrating my arm and I don't need to worry bout it as nobody in the room (or even neighbour) affected by the sound, as only me knowing is time to wake up. It monitor sleeps too.

Another way is by setting aircond timer (if you using it daily). I set my aircond to switch off 30min before my time to wake up. As I am sensitive to temperature change, usually when I feel the room slightly warmer, I will wake up. And my hubby & son, very deep sleeper.. they won't feel it that soon, and I manage to on the fan for them.