How Your Baby’s Biological Clock Works — And How to Prevent Early Morning Wakes
Written by Chloe Roche — Certified Baby & Toddler Sleep Consultant
Chloe Roche is the founder of Sleep Again, helping families with gentle, science-based sleep training and personalised sleep plans. She supports parents through challenges such as early morning wakes, short naps, and bedtime struggles, guiding babies and toddlers toward healthy sleep habits.
One of the biggest challenges many parents face is a baby who loves to rise with (or before!) the sun. While those 4:30am starts may feel impossible to shift, the good news is that your baby’s biological clock — also known as their circadian rhythm — can be gently guided through everyday routines.
As a sleep consultant, I often explain to families that babies’ body clocks are primarily set by three powerful “time-givers” (called zeitgebers in sleep science): light, food, and social interaction.
When used consistently, these cues help your little one learn when it’s time to wake, play, and rest — and importantly, when it’s time to stay asleep a little longer in the morning.
🌙 Why babies wake early in the morning
Babies’ sleep cycles are naturally shorter than adults, and their light sleep phases often occur in the early morning hours (around 4–6am). Combine this with rising cortisol levels (the body’s natural awake hormone) and even the smallest environmental cue — light peeking through curtains, a flushing toilet, or even a car backing out of the driveway — and your baby may be ready to start the day long before you are.
This is why creating strong morning cues and limiting early stimulators are essential in helping your baby’s circadian rhythm settle into a healthier wake time.
Some parents think their babies are ready to start the day at 5am, but in reality true ‘larks’ optimally should start their days no earlier than 5:45am and any earlier than this is usually a sign that something is occurring in their sleep environment to wake them, they may be unwell or they may be having too much or too little day sleep and a bedtime that is too early or too late (oh the joys for this sleep detective!).
🌞 The three keys to setting your baby’s biological clock
1. Light exposure
Take your baby outside for natural light exposure within the first hour of waking. Morning sunlight is the strongest signal to the brain that “the day has begun.” We aim to always have baby up by 7am and no earlier than 6am to keep their day and naps on track.
Ensure their sleep space is very dark overnight and in the early morning hours. Even small amounts of light (early sunrise glow, or standby lights from devices) can suppress melatonin and signal it’s time to wake. Blackout blinds are a game-changer here (or, even taping your black-out blinds to the wall or using suction cup block-out blinds on the windows behind!)
2. Food
Offer the first milk feed of the day after 6am, not during early waking hours. Feeding too early can reinforce the idea that the day begins at 4:30–5:00am.
Once solids are established, a nutritious breakfast around 7am helps anchor your baby’s circadian rhythm and stabilise blood sugars for the morning ahead.
3. Social interaction
Babies thrive on connection. Smiles, eye contact, talking, and playtime all tell your baby: this is morning time.
Try to keep interactions minimal and calm if your baby wakes too early (before 6am). Low lights, gentle shushing, and resettling strategies help communicate that it’s still sleep time.
💤 Practical tips to reduce early rising
Bedtime matters: Avoid putting your baby down too late. Overtired babies often sleep more lightly and wake earlier.
Consistent routine: A predictable bedtime routine (bath, milk (with a degree of separation before sleep), story, cuddle) helps your baby’s body know when to expect sleep.
Check the sleep environment: Dark, cool (20–22°C), baby dressed appropriately so they don’t become cold from 3am onwards as the sun begins to rise, white noise on, and free of distractions.
Delay morning cues: If your baby wakes at 5am, resettle calmly in the dark. Save the morning feed, light, and smiles until after 6am.
✨ The bottom line
Your baby’s biological clock is guided by light, food, and social interaction. By aligning these cues with your desired wake times, you can help your baby learn to sleep later into the morning — and gift yourself and your family more restorative sleep.
Remember, every baby is unique. Early rising is one of the most common sleep challenges I support families with, and often just a few simple adjustments can make a world of difference.
💕 Need help with early rising?
As a certified Infant and Child Sleep Consultant, my passion is to create personalised sleep plans that help families overcome challenges like early morning wakes, short naps, and frequent night waking.
If your baby is rising with the birds and you’re ready to start your day not at an ungodly hour, I’d love to support you.
Book a consultation with Sleep Again and let’s help your little one reset their mornings.