These conflicts must be checked out and dealt with. Weed out the distractions. Many activities interfere with children falling asleep in a timely manner. They may have a radio or TV in their bedroom and don't turn it off until late at night. They may be listening to music past the curfew.
Many teens like to chat on the phone with their friends until the wee hours of the morning.
If there are distractions, they need to be eliminated to solve the morning rising problems. Attach a penalty. Children may have to get up earlier the next morning following a late rising. If they're 15 minutes late, then they have to only get up 15 minutes earlier the following morning.