wake up a heavy sleeper without screaming
It is a matter of building a dialog. 'Wake up" etc while doing something else is not efficient. You have to pay attention to the person.
1- Go next to the person.
2- Speak as if he/she is awake.
3- Repeat gently about one of the reason why the time is geeting late
"Missing the bus", "Breakfast is ready", "bathroom is necessary" etc.
4- Keep using the name of the person while addressing. Say the name first and let him/her respond, then continue.
5- Do not dump a lot of information.
6- If there is something new, remind him/her. such as "Remeber today we have to go to mall after the work" etc.
7- Ask the person to do some action such as 'high five'
8- Do not be serious and threatining.
9- Keep smiling or laughing nicely.
10- Use drip of water if the person agreed about it earlier.
11- Never use "SNOOZE" for the alarm clock.
12- If the person was able to wake up by themselves when you are not there by alarm clock, then be patient and do not turn off the alarm clock let them do it.it For some people it takes time to register the alarm clock, give their time.
13- If nothing works "Ask the person to move his/her hand or high five if they decide to continue to sleep. Then let them sleep over and get damage. Next day it will be much easier"