IPhone 13 stuck in sleep mode in the morning

I recently upgraded my iPhone XS to iPhone 13 and also bought the new Apple Watch. Now I’m seeing that my phone is still in sleep mode sometimes even hours after I stop the alarm. I have to manually turn it off. I’ve been using sleep mode for a while and never had this happen. I don’t know what changed and it’s pretty annoying since I miss notifications until I remember to access the phone and turn it off. Any help will be appreciated.