Sleep Basics - how sleep works

“Sleep is biological, not behavioural” 

The most important thing to understand is that sleep isn’t a behaviour to fix. It’s a biological process, shaped by your child’s development, temperament, sensory needs, and environment. 

How and when your child sleeps is guided by their biology, not by how “good” your parenting is. It’s simply a reflection of who your child is and what they need. 

The goal is to work with your little one to align sleep in a way that suits them and you best. When making changes to sleep, we should be considering changes from all areas, rather than just one area alone. 

There are two biological drivers of sleep: sleep pressure and the circadian rhythm. 

Let’s break them both down so you can understand the basics of how sleep works. 

1. Sleep Pressure (Homeostatic Sleep Drive) 

What is sleep pressure? 

Imagine your baby’s sleep pressure is like a bathtub filling with water. 

As soon as your baby wakes up, the sleep pressure tap turns on, and it fills the tub slowly throughout the day. The longer they stay awake, the more water builds up, and the fuller the tub gets. 

Naps? They’re like letting out a bit of water. Not enough to empty the tub completely, but just enough to stop it from overflowing too soon. These little “drains” help your baby reset so they can get through to the end of the day without becoming too overstimulated and dysregulated (really tired). 

The goal? By bedtime, the tub is full, but not overflowing, and that beautiful full tub of sleep pressure aligns with their circadian rhythm (the body’s natural clock that knows it’s night), making it much easier for them to fall and stay asleep overnight. 

The catch with sleep pressure: 

Every baby responds to sleep pressure differently. 

Some babies don’t need much sleep pressure to sleep well. In fact, if they’re awake for too long, they’ll tip into being overstimulated and dysregulated, and sleep will fall apart. These little ones need more frequent or longer “sleep pressure releases” through naps to help them stay regulated. 

Other babies can handle a lot more sleep pressure. They often need longer awake times during the day (compared to other babies their age) to build up enough pressure for a solid night’s sleep. If these babies don’t stay awake long enough between naps, it can feel hard to get them down (like they’re fighting sleep), and their naps tend to be short because the sleep pressure just isn’t high enough to help them fall asleep easily and stay asleep. If they get too much day sleep, it can take away from their night sleep, leading to more frequent night waking. 

This is where sleep becomes personal. There’s no one-size-fits-all approach. 

Parent tip for supporting sleep pressure balance: 

Think of naps like a pressure release valve. They’re not about following rigid schedules or hitting perfect nap lengths; they’re about letting off just enough steam so your baby doesn’t get overstimulated. 

This analogy gives you permission to be flexible. Some days your baby might need a longer nap, other days a quick cat nap will do. What matters is the overall balance between awake time and rest, not how perfectly each nap fits a schedule. 

Let the tub analogy guide you, not the clock. And remember: trial, error, and tuning into your baby always wins over rigid rules. 

2. Circadian Rhythm (Body Clock) 

• The circadian rhythm regulates the sleep-wake cycle. It is influenced by: 
• Exposure to daylight and darkness 
• Social interaction 
• Feeding patterns 
• Connection 

Babies are not born with a circadian rhythm. It begins developing around 2–3 months of age. 

Parent tip for supporting circadian rhythm: 

Nap your baby in lighter rooms rather than pitch-black spaces, especially during the newborn stage. This light exposure helps your baby develop and set their circadian rhythm so they can begin to distinguish day from night. 

Another tip is to expose your baby to natural daylight as early in the day and as often throughout the day as you can, especially in the morning. A walk outside after the first nap, or playtime outside, or near a bright window when they get up in the morning, helps signal to your baby’s brain: “Hey, it’s daytime now!” 

In the evening, dim the lights and reduce stimulation about an hour before bedtime. This helps their body wind down and supports the natural rise in melatonin (the sleep hormone). 

It doesn’t have to be perfect every day, but small, consistent cues - like light and darkness - go a long way in helping your baby’s body clock know day from night and make sleep feel easier. 

Sleepy babies 

Some newborns can be particularly sleepy, especially if they are jaundiced. If your baby is sleeping for long periods, not waking for feeds, not feeding well, not having many feeds, or seems too tired to feed - it’s important to contact your LMC or doctor.