You might notice your child quickly gets the hang of daytime potty training, but nighttime is a whole different story — and that’s completely normal.

In fact, it’s very common for children to be day-trained months (or even a year or more) before they consistently stay dry overnight. Here’s why:

It’s About Biology, Not Willpower

Staying dry at night isn’t just a skill; it depends heavily on your child’s bladder development, brain, bladder communication, and hormone production.

1. Bladder Capacity

At night, your child’s bladder needs to hold urine for 10–12 hours, a much longer stretch than during the day. Some children simply have smaller bladders or don’t yet have the muscular control to hold it that long.

2. Brain; Bladder Signalling

Staying dry overnight means the brain needs to:

• Recognise a full bladder while asleep
  

• Send a signal to wake up the body
  

• Get up and go to the toilet
  
  

That’s a lot for a young nervous system to coordinate! This brain-bladder communication develops at different ages for different children.

3. Hormone Maturity (ADH)

The body produces a hormone called antidiuretic hormone (ADH), which reduces urine production at night.
In many toddlers, this hormone hasn’t fully matured yet, meaning they produce just as much urine at night as they do during the day; making it harder to stay dry.

This hormone usually starts functioning more effectively between ages 4 and 7, which is why nighttime dryness often comes much later than daytime control.

What This Means for You:

• Don’t stress if your child still needs nappies or pull-ups at night, even if they’re fully trained during the day
  

• Waking up wet is not a regression or a discipline issue — it’s often just biology doing its thing
  

• Use protective sheets and keep things low; pressure
  

• Wait until your child consistently wakes dry before ditching night nappies

• Avoid night training during big transitions (new siblings, moving house, etc.)
  

Bottom line?
Day training is a skill your toddler learns. Night training is a stage their body grows into.

Be patient, trust the process, and remember, dry nights will come in time, with the same loving support that helped them succeed during the day.

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How Potty Training Can Disrupt Sleep

1. Increased Awareness = More Wake; Ups

As toddlers start learning to tune into their bladder signals, they can become more aware of the need to wee, even during sleep.
This can lead to:

• More night wakings
  

• Sudden nap resistance
  

• Lying awake, calling out, “I need to do a wee!”  even when they don’t
  
  

At this stage, their brain is still learning to interpret these signals and respond appropriately, and it often means more disruption before better sleep returns.

My winning strategy for this stage of yo-yo-ing out of bed, claiming they need to wee every 5 minutes: Give them two special tokens they can use for the toilet after bedtime, once the tokens are used up, their visits are done. This gives them a sense of control, gives you a limit and clear expectations without having to fight and yell. It gamifies the toilet tactic. 

2. Fear or Anxiety Around Accidents

Some toddlers develop anxiety about having an accident, which can create resistance around sleep. For example:

• Refusing to wear a nappy at night, but waking multiple times, anxious about wetting the bed

• Insisting on multiple toilet trips before bed ("one more wee!")
  

• Avoiding naps due to a fear of losing control
  
  

This can be especially tricky with strong-willed or sensitive temperaments.

3. Changes to the Bedtime Routine

Toilet trips become part of the pre-bed routine, and some toddlers use this as a stalling tactic:

“I need to go again…”
“I forgot to do a wee…”
“What if I have to go while I’m asleep?”

This new element of bedtime can prolong things, create frustration, or disrupt sleep cues if not handled consistently.

4. Nappy Changes at Night = Fully Awake Toddlers

If your toddler is still wearing a night nappy and wakes wet or partially wet you may feel obligated to change them immediately. But for some toddlers, that disruption can:

• Wake them up fully
  

• Make it hard to resettle
  

• Reinforce night waking as a “thing” again
  

5. Nap Disruption During the Training Period

During daytime training (especially in the first 3–5 days), you may:

• Keep them in undies and worry about accidents
  

• Wake them mid; nap to try using the potty
  

• Keep them up longer to avoid accidents
  
  

This can easily result in overtiredness, shorter naps, or nap refusal, which then impacts night sleep.

What You Can Do to Minimise Sleep Disruption

• Use pull-ups or nappies during sleep until your child is regularly dry; potty training doesn’t have to be all or nothing
  

• Build the toilet into your bedtime routine, but keep it consistent (one last wee, then lights out)
  

• Avoid big changes during other transitions (moving house, sleep regressions, etc.)
  

• Reassure your child if they’re anxious, but don’t overemphasise accidents or night waking
  

• Keep naps as normal as possible during the day, potty training can wait until after a nap if needed
  
  

Potty training is a developmental leap, and like all leaps, it can temporarily disrupt sleep.
But with calm, consistent responses and realistic expectations, sleep will return to normal, and you’ll have one more milestone under your belt.

Emma Purdue

Emma is the owner and founder of Baby Sleep Consultant, she is a certified infant and child sleep consultant, Happiest Baby on the block educator, has a Bachelor of Science, and Diploma in Education. Emma is a mother to 3 children, and loves writing when she isn't working with tired clients and cheering on her team helping thousands of mums just like you.