Teenagers are not lazy. Their body clocks genuinely run later, and they need more sleep than adults. Here is the science, and the times.
During adolescence, the brain is developing at a significant pace. Connections are being pruned and strengthened, emotional regulation is being established, and memory from the day is being filed and consolidated. Almost all of this happens during sleep.
Research consistently shows that teenagers who get the sleep they need perform better academically, manage stress more effectively, are less likely to experience anxiety and low mood, and recover from illness more quickly. The body's growth hormone is also released primarily during deep sleep, which is why tired teenagers can feel physically heavy as well as mentally foggy.
The teenager who won't get out of bed at 7am is not (necessarily!) being difficult. Their melatonin release starts later in the evening and winds down later in the morning than it does in adults. Their biology is running a different schedule to the school day, and that gap has real consequences for their wellbeing.
Puberty triggers a shift in the circadian rhythm of about two hours. This is biological and means teenagers, whose melatonin starts rising after 11pm, will be naturally inclined to stay up late and sleep late. It feels incompatible with the rest of the human race, but it is the natural circadian rhythm of teenage hormones.
Schools that have shifted their start times later have reported measurable improvements in attendance, attainment, and student mental health. The evidence is real and mainstream. But until all schools can break their dogma and follow the science, the best strategy is to work with the biology: consistent bedtimes, no screens for at least 45 minutes before sleep, a cool and dark room, and a bedtime that allows for the full nine hours whenever possible.