Understanding baby sleep and split nights: causes and solutions

Sleep is one of the most talked-about aspects of life with a baby – and for good reason. Just when you think you’ve cracked the code, a new challenge pops up. One common sleep disruption that leaves many parents scratching their heads is the dreaded split night. If your baby is waking up in the middle of the night – wide-eyed, alert and ready to party – you’re not alone. Let’s explore what causes split nights and what you can do to get your little one’s sleep back on track.

What’s a split night?

A split night is when your baby wakes in the middle of the night and stays awake for an extended period – often 1-2 hours (or more!) – before eventually falling back asleep. Unlike typical night wakings (which usually involve some fussing and a quick resettling), split nights often come with calm, happy alertness. It's like your baby suddenly decides 2am is a great time to play.

What causes split nights?

Split nights are usually linked to circadian rhythm and sleep pressure – two key components of healthy sleep. The most common causes are:

1. Too much daytime sleep

Babies need a certain amount of total sleep over a 24-hour period. If they’re napping too much during the day, they may not build up enough sleep pressure to sleep solidly through the night.

2. Too little sleep pressure at bedtime

If your baby goes to bed too early or hasn’t been awake long enough before bedtime, their body might treat the night as two separate naps. After a few hours of sleep, they wake up refreshed and ready for a second round.

3. Developmental changes

Around 4 months, 8-10 months, and again around 12-18 months, your baby’s brain is developing rapidly. These milestones can lead to sleep disruptions as they process new skills like rolling, crawling, walking, or talking.

How to help resolve split nights

Here’s what you can do to reduce or eliminate split nights:

1. Adjust nap lengths and timing

Track how much daytime sleep your baby is getting. Gradually reduce naps if they’re sleeping more than average for their age. Aim for age-appropriate wake windows, especially before bedtime.

2. Push bedtime later

If your baby is going to bed very early, try pushing bedtime 15 minutes later every few nights to help build more sleep pressure.

3. Keep night wakings low-stimulation

During those wakeful periods, keep lights low and voices soft. Avoid engaging or playing –even if your baby seems ready to party. This helps reinforce that night is for sleeping.

4. Offer a consistent bedtime routine

A calming, predictable bedtime routine helps signal to your baby that it’s time to wind down and go to sleep. Think warm bath, soft lighting, a lullaby and a cuddle or story.

5. Evaluate their sleep environment

Ensure your baby’s room is dark, quiet and cool (ideally 18–22°C). Blackout curtains and white noise machines can work wonders.

6. Be patient with developmental phases

Sometimes, split nights are just part of a developmental leap. Keep routines consistent and wait it out – often the issue resolves itself in a few weeks.

Still struggling?

If split nights are happening regularly and your baby seems tired during the day, or if you're unsure whether they're getting the right amount of sleep, get in touch to see how I can help. Simply book a free 15-minute discovery call, here.

Final thoughts

Split nights can be exhausting, but they’re usually temporary and often linked to changes in your baby’s sleep needs. By tuning into your baby’s sleep cues, adjusting their schedule, and creating a sleep-friendly environment, you can help guide them back to restful nights – for both of you.

Sleep consultant in Surrey