The argument happens in most households with a teenager in it. They can't get to sleep, they can't get up, and the obvious conclusion is that they should go to bed earlier and put the phone down.
Phones genuinely don't help. But there's something underneath that isn't behavioural.
The body clock moves
During adolescence the circadian rhythm shifts later — a delay of roughly one to three hours compared with childhood. Melatonin starts being released later in the evening, so the biological signal to sleep simply arrives later than it used to.
This is a documented developmental change, not a character flaw. Asking a fifteen-year-old to fall asleep at ten can be close to asking an adult to fall asleep at seven.
It reverses in the twenties, which is why this resolves on its own eventually.
The collision
The clock shifts later; school start times don't. So the sleep gets taken off the front end, every school night, cumulatively.
That matters because adolescents need more sleep than adults, not less — typically 8 to 10 hours — during a period of significant brain development. For comparison, what adults actually need, and what short sleep is associated with, is a lower number than that. The weekend lie-in is the body attempting to repay a debt, which is why it's so ferocious and why it also makes Monday worse by shifting the clock later again.
What actually helps
Morning light. The most underused lever. Bright light soon after waking pulls the clock earlier, and it's free. Curtains open, breakfast near a window, walk rather than car if possible. This is the same mechanism behind why sleep gets harder in winter, when morning light is in short supply.
Consistent wake time, including weekends. More important than bedtime, and the hardest sell in this entire article. A lie-in of an hour is manageable; three hours resets the clock later.
Evening light down, and phones out of the bedroom — as much for the social stimulation and the notifications as for the light itself.
Caffeine audit. Energy drinks are common among teenagers, often consumed in the afternoon, and contain far more caffeine than people assume. This alone can account for a great deal.
What we would not do
We don't sell supplements for teenagers, and we wouldn't suggest it here. Our labels say under-18s should consult a physician before use, and we mean it rather than treating it as boilerplate.
Melatonin in particular is worth a specific note: it is a hormone, it is prescription-only for under-18s in many countries for good reason, and giving it to a developing adolescent is a decision for a doctor rather than a parent and a search engine. What the dose-response evidence actually shows in adults is a separate question again, and the answer is lower than most products assume.
When it's worth getting looked at
If the problem persists through holidays with no school pressure, if there's snoring or daytime sleepiness that a lie-in doesn't fix — sleep apnea occurs in adolescents too — or if low mood or anxiety is in the picture. Any of those is more than a body clock.
This article is not medical advice. Decisions about a young person's sleep, and anything given to them, belong with a doctor.