The amount of sleep your teen is getting and the regularity of their sleep schedule is most important, so sleeping until the late morning may actually be okay.
Newborn sleeping too much: What is normal and what to do
Teens Sleeping Too Much, Or Not Enough? Parents Can Help
The 3-Year-Old Sleep Regression in Toddlers
When a teen's tiredness signifies a serious health problem
Is Your Teen Getting Enough Sleep?: Laurel Pediatric & Teen Medical Center: Pediatricians
Back to school: Teachers let students sleep in class. Here's why.
My Son Sleeps All Day and Is up All Night” - Parents Ask
Kids' sleep: answers to 20 FAQs
Sleep & children 3-5 years: what to expect
Snoring: When To Be Concerned