A 16-year-old female presents to her pediatrician for a routine check-up, reporting difficulty waking up for school at 6:30 AM. She states she can’t fall asleep until around 2 AM despite trying to go to bed earlier. She feels groggy and occasionally dozes off during morning classes but is alert after lunch. She plays soccer after school, which keeps her energized until 7 PM, and she naps for an hour some afternoons. On weekends, she sleeps from 2 AM to noon without issue. She keeps a sleep log for two weeks, showing 5-6 hours of sleep on weekdays and 10-11 hours on weekends. She avoids caffeine, has no screen time after 10 PM, and denies snoring. Physical exam reveals a healthy teenager with a BMI of 21 kg/m², normal blood pressure, and no signs of depression or anxiety. What is the most likely diagnosis for this patient’s sleep difficulties?
