> The killer feature of modern watches is the vibration alarm - you can wake up even if you use earplugs/headphones/noise machine and you won't wake up anyone else along with you.
Probably depends a lot on the person. A phone already does that for me, and doesn't have the associated uncomfortableness of wearing a watch while I sleep.
Indeed, I didn't see studies so my theory is that most people find sleeping with a phone in the bed much more uncomfortable than with a watch on the wrist.
If it's not in the bed then its vibrating not going to reach you, what wakes you up is the noise it makes while vibrating on some surface and this noise is heard by others just as well.
Probably depends a lot on the person. A phone already does that for me, and doesn't have the associated uncomfortableness of wearing a watch while I sleep.