My MI band v1 used to do that and it was like $10. It had both these features (vibrating wrist alarm and REM sleep detection alarm) and the battery lasted for a

My MI band v1 used to do that and it was like $10. It had both these features (vibrating wrist alarm and REM sleep detection alarm) and the battery lasted for a month on a single recharge. I don't know the compatibility with iOS but you can buy it and put it on every night to solve your problem.