Summer bedtimes drift late. School start times don’t. That gap is why so many kids and teens walk into the first week of school running on four to six hours of sleep.

If your child can’t fall asleep before midnight and can’t wake up before 10am, this isn’t laziness or bad habits. It’s a circadian rhythm that has shifted later than the school schedule requires. The good news: you can shift it back, and you don’t need to wait until the night before school starts.

What’s actually happening

Delayed sleep phase means the body’s internal clock is set later than the desired sleep schedule. The brain doesn’t release melatonin until later at night, so sleep drive and circadian timing don’t line up until closer to midnight or beyond.

Left alone, this doesn’t fix itself in a day. The body clock moves in small increments, usually 15 to 60 minutes a day at most. That’s why a one-night effort (“just go to bed early tonight”) almost never works. You need a plan that runs across one to two weeks.

Step 1: Start the shift 1 to 2 weeks before school

Pick a wake time 30 to 60 minutes earlier each morning for the first few days, then repeat until you land on the school wake time. Bedtime will naturally follow once the morning shift takes hold.

Trying to force an early bedtime first almost always fails. The kid lies in bed wide awake because their body isn’t ready for sleep yet. Anchor the wake time and let bedtime catch up.

Step 2: Get bright light first thing in the morning

Morning light is the single strongest signal for resetting the circadian clock earlier. As soon as your child wakes up:

• Open the blinds or go outside for 15 to 30 minutes
• Natural daylight works better than indoor lighting, even on a cloudy day
• If getting outside isn’t possible, a light therapy box (10,000 lux) for 20 to 30 minutes at wake time is a reasonable substitute

Research groups including the American Academy of Sleep Medicine recommend timed bright light exposure as a core treatment for delayed sleep-wake phase disorder in kids and teens, usually paired with a behavioral sleep schedule.

Step 3: Cut evening light exposure

Light in the two to three hours before bed pushes the clock later, working directly against your morning light effort. Practical version of this:

• Dim household lights in the evening
• Phones and tablets off or on night mode at least an hour before bed
• If screens are non-negotiable, blue-light blocking glasses in the evening can help, though dimming and reducing screen time works better than glasses alone

Step 4: Use melatonin correctly, if needed

Melatonin isn’t a sedative. It’s a timing signal. Used correctly, it tells the body “start moving bedtime earlier.” Used incorrectly (too high a dose, too close to the desired bedtime), it mostly just makes the sedation, not the phase shift.

What the evidence supports:

• Low dose. Studies in kids and teens with delayed sleep phase used doses in the 0.5mg to 3mg range, not the 5 to 10mg doses sold in most stores
• Timing matters more than dose. Give it 3 to 5 hours before the current natural sleep onset time, not right at the new target bedtime
• A pooled analysis of 19 randomized trials in children and adolescents with delayed sleep phase disorder found melatonin consistently improved sleep onset by 22 to 60 minutes with no serious adverse effects
• Talk to your child’s doctor before starting, especially if there are other medications or health conditions involved

Step 5: Hold the wake time on weekends too

This is where most families lose the progress they built during the week. Sleeping in on Saturday and Sunday resets the clock later again, and Monday morning feels like starting over.

Keep wake time within about an hour of the school-day wake time on weekends. If your child is genuinely sleep deprived, a short nap earlier in the day is a better fix than sleeping in for three extra hours.

Step 6: Build the wind-down routine

Once the schedule is shifting, a consistent pre-bed routine helps lock it in:

• Same order of activities each night, roughly 30 to 45 minutes before lights out
• No caffeine after early afternoon, this includes soda and some teas
• Bedroom cool, dark, and used for sleep, not for scrolling or homework
• Exercise earlier in the day. Vigorous activity close to bedtime can delay sleep onset further

Step 7: Know when to get help

If you’ve run this plan consistently for two to three weeks and your child still can’t fall asleep before midnight, still can’t wake up without a major fight, or is falling asleep in class, it’s worth a formal evaluation. Delayed sleep-wake phase disorder is a diagnosable condition, and a sleep medicine specialist can confirm timing with tools like a sleep diary or actigraphy and adjust the light and melatonin protocol with more precision.

The bottom line

Delayed sleep phase responds well to a structured plan built around morning light, evening light control, correctly timed low-dose melatonin, and a wake time that doesn’t move on weekends. Start the shift one to two weeks before the first day of school, not the night before, and give the body clock time to catch up gradually instead of forcing it overnight.

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References

• Van Geijlswijk IM, et al. Efficacy and safety of supplemental melatonin for delayed sleep-wake phase disorder in children. Sleep Med Rev, and related meta-analysis of 19 RCTs (841 children and adolescents).
• Saxvig IW, et al. A randomized controlled trial with bright light and melatonin for the treatment of delayed sleep phase disorder. J Biol Rhythms. 2013;28:306-321.
• Gradisar M, Dohnt H, Gardner G, et al. A randomized controlled trial of cognitive-behavior therapy plus bright light therapy for adolescent delayed sleep phase disorder. Sleep. 2011;34:1671-1680.
• American Academy of Sleep Medicine. Clinical practice guideline for the treatment of intrinsic circadian rhythm sleep-wake disorders, 2015 update.
• Smits MG, et al. Melatonin treatment in adolescents with delayed sleep phase syndrome. PubMed (retrospective study of 33 adolescents).