Brain chemicals · Melatonin

What does melatonin do? Your kid’s own night signal, explained

Melatonin is a hormone the body makes in the evening to signal that night is coming. It doesn’t knock a child out; it helps set the timing of sleepiness. Bright light, especially from screens, turns it down, which can push sleep later. Dim evenings, steady bedtimes and morning daylight let the body’s own signal do its job.

Updated Oct 26, 2026 · Little Brain Crew editorial team · How we write

Mela: whispers “night is coming” so the body gets sleepy

Say it to your kidMela is the helper who whispers “night is coming” to your body so you start to feel sleepy. But Mela is shy around bright lights. When the lights are bright and the screen is on, Mela hides. So let’s make the house cozy and dim, and Mela will come out.

What is melatonin, and where does it come from?

Melatonin is a hormone made by a tiny gland in the brain called the pineal gland. It rises in the evening when light fades, stays up through the night and falls toward morning. It acts less like a sleeping pill and more like a clock hand. It tells the body what time it is, and the body begins to feel sleepy as a result.

In the crew, that is Mela, the helper who whispers “night is coming.” Corti wakes the body in the morning. Mela puts it to bed.

How does light change a child’s melatonin?

Strongly, as it turns out. In an in-home study of 36 preschoolers aged 3 to 4.9 years, an hour of light before bedtime, from dim to very bright, suppressed melatonin by about 85% on average, with a range of 69 to 99%. Even the dimmest group, 5 to 40 lux, about what a low lamp gives, averaged about 78%. Young children seem especially sensitive to evening light.

A caution: lower melatonin in a lab is not the same as proven worse sleep. But it fits what sleep experts suggest, and it makes the habit easy to remember: dim, dull, same. Dim the house in the last hour, keep it quiet, and do the same things in the same order each night.

Our villain Glo is bright evening light, and Bedi is the phone in the bedroom. Neither is a person or a bad kid. They’re habits that make Mela hide.

Why does my teen stay up so late?

Because in adolescence the body clock really does shift later. Research reviews find that melatonin timing moves later in teens, and they get sleepy later at night. Evening light may push a teen’s clock later still, and school start times often come too early.

Teens need about 8 to 10 hours (the sleep medicine consensus range for ages 13 to 18). Many get far less on school nights. Rather than fight the clock, protect what you can: a steady wake-up time, bright light in the morning, and phones charging outside the bedroom.

What helps Mela do her job?

Mostly the same few ideas, repeated until they feel boring. Boring is the goal at bedtime.

Dim, warm light an hour before bed. Lamps instead of overheads.
Screens off an hour before bed. And off in the bedroom overnight.
Phones charge in the kitchen. Yours too.
A similar bedtime every night. Weekends included, give or take an hour.
Morning daylight. It helps anchor the clock the next evening.

What about melatonin gummies?

This page is about the hormone your child’s body makes on its own, and we cover habits only. Melatonin sold in gummies or pills is a different matter. Ask your pediatrician first, before giving any, and bring up the sleep problem you’re trying to solve. Often there are habit changes worth trying, or a cause that needs looking at.

What you’ll see at home

Wired and giggly at bedtime, then slow and grumpy in the morning
Lights out at nine and awake at ten-thirty
A phone that charges next to the bed
A teen who is wide awake at midnight and exhausted at 7 a.m.

Try tonight

Switch to lamps and warm light an hour before bed.
Charge every phone in the kitchen, yours included.
Keep bedtime the same as last night, even if it was a good night.

What to say

Instead of“Why aren’t you asleep yet?!”
Say“Your body’s sleepy signal is shy. Let’s keep it dark and quiet.”
It takes the pressure off falling asleep.
Instead of“Give me that phone, it’s bedtime!”
Say“Phones sleep in the kitchen, everyone’s, starting tonight.”
A rule for the whole house is easier to accept.

Want the whole crew on your side?

The Kid Brain Toolkit: the 12 hardest moments decoded, from screens off to bedtime, with what to say and what to try tonight. Read it in one evening.

See the plans

The Toolkit is $9, one payment. For learning only, not medical advice.

Questions parents ask

Is melatonin a sleeping pill?

The hormone your body makes is a timing signal. It tells the body it’s night, and it doesn’t force sleep. Whether to give any melatonin product to a child is a question for your pediatrician.

Do screens really disrupt kids’ sleep?

Bright evening light lowered melatonin in preschoolers in one study, and a phone in the bedroom is linked with shorter sleep in observational research. Screens off an hour before bed is a simple habit that costs nothing.

How much sleep does my child need?

Consensus ranges are 10 to 13 hours for ages 3 to 5, 9 to 12 for ages 6 to 12 and 8 to 10 for ages 13 to 18, counting naps for the youngest. See our sleep guide for the full table.

Sources

Educational content only, built on everyday habits. It’s not medical advice, a diagnosis or a treatment. If something about your child’s sleep, mood, growth or behavior worries you, talk to your pediatrician.