Why Are Teenagers Always Tired?

Puberty triggers a genuine, biologically-driven shift in circadian phase — teenagers' body clocks shift approximately 2 hours later than adults or younger children. The melatonin onset (the sleep-promoting hormone) occurs later in the evening, making it biologically difficult for teenagers to fall asleep before 11pm–midnight, regardless of willpower.

When school starts at 7–8am, teenagers are being woken during what their biology considers the middle of the night. The resulting chronic sleep deprivation impairs attention, memory consolidation, emotional regulation, and decision-making — affecting academic performance, mental health, and accident risk.

Screen use in the evening (extremely common in teenagers) exacerbates the already-delayed circadian phase through blue light melatonin suppression. Social activities and social media naturally occurring in the evening push sleep later still.

Teenagers also have genuinely higher sleep requirements than adults — 8–10 hours per night is the physiological recommendation, compared to 7–9 for adults. The combination of needing more sleep and having it curtailed more severely produces acute and chronic sleep deprivation in most school-attending adolescents.

Later school start times are the most evidence-based intervention at a systemic level, and districts that have implemented them show measurable improvements in academic performance, mental health, and accident rates. Where this isn't possible, individual interventions help at the margins: strict screen curfews (no phone after 9pm), morning light exposure immediately on waking, and protecting the weekend sleep opportunity.

Supplemental melatonin (0.5–1mg) taken 1–2 hours before desired sleep onset can advance the circadian phase slightly in delayed sleep phase teenagers. It is not a sleeping pill — it's a circadian timing signal — and low doses are more effective than high doses for this purpose.