Apple Watch/iPhone Alarm

How do I set my bedtime/awake alarm to ring on my iPhone ONLY! I have not been able to wear my Apple watch to track my sleep, due to the fact that the alarm only vibrates on my wrist. This is not enough to wake me up. Last night I fell asleep with it on, and it did not wake me, even though my iPhone was sitting right beside. This made me late to work! 😩