Understanding your baby's sleep cycle
Louisa Sherlock
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As soon as you've had a baby, you'll probably become quite obsessed with the subject of sleep – especially if no one's getting much of it! To help improve things, it's a good idea to understand your baby's sleep in a bit more detail. Here comes the science part ...
With over half of parents saying their baby or child wakes up at least once in the night, sleep is a rare thing for many new parents.
But understanding sleep cycles, how much sleep your baby needs and why she keeps waking up can help you understand your baby's needs that bit better.
We spoke to children's sleep specialist Andrea Grace to get the science behind your baby’s sleep, including:
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- the different stages of sleep;
- how your baby's sleep cycles are different to yours;
- how much sleep your baby really needs.
What happens when my baby falls asleep?
The answer: a lot!
According to the Sleep Foundation, sleep is especially important for your baby as it directly impacts on her mental and physical development.
And just like you, your baby alternates between different stages of sleep although her sleep cycles are much shorter.
Here’s the science behind your baby's sleep...
NREM Sleep (Non-rapid eye movement)
As your baby starts to fall asleep, she'll enter NREM (non-rapid eye movement) sleep. This is also known as ‘quiet’ sleep.
Your baby will spend around 50 percent of her time in this stage until she’s around six months when it increases to around 70 percent of her sleep. Adults are in NREM sleep for around 75 percent of the night.
Young children plunge rapidly through drowsiness and lighter stages of NREM into deep sleep usually within 10 minutes.
Here's what your baby’s body will be doing in the different stages of NREM:
Stage 1
This is the transition phase between wakefulness and sleep. It's a light sleep which she can be easily woken up from it.
It's normal to wake up during this sleep phase, and as adults we can go back to sleep. This waking can be a problem in for your baby who can't settle herself back to sleep alone.
Stage 2
This is a light sleep and during this stage, your baby’s breathing and heart rate are regular and her body temperature drops.
Stage 3
This is the deepest stage of sleep and a lot is happening during this stage according to the Sleep Foundation, including the release of important hormones needed for growth and development.
This deep sleep is when some children experience night terrors, sleep walking, or bed wetting.
REM Sleep (Rapid Eye Movement)
This REM sleep - also known as ‘active’ sleep - is the final stage of sleep and accounts for about 50 percent of your baby’s sleep. By the time she’s six-months-old this will drop to around 30 percent of her sleep.
However as a newborn, she'll enter REM sleep almost immediately after dropping off. By three-months-old she will enter NREM sleep first, the same as adults.
Andrea says:
‘Babies are much more active in their sleep than adults. REM sleep accounts for at least half of a baby’s sleep, unlike adults who just have 20-25% of the night’s sleep in REM sleep.
‘This kind of sleep is important for brain development.’
According to the Sleep Foundation, during this stage, your baby will have bursts of rapid eye movements, darting back and forth, up and down. This is the stage of sleep in which most dreaming occurs.
As she sleeps your little one will follow a pattern of alternating REM (rapid eye movement) and NREM (non-rapid eye movement) sleep, just like you do.
However her sleep cycles are much shorter - they last round 50 minutes in babies compared to 90 minutes in adults.
The differences between REM sleep and NREM sleep
- Body twitches.
- Eyes flicker.
- Smiles and frowns.
- 50% of all sleep at birth.
- 20% of all sleep for adults.
- Older children and adults may dream.
- Occurs mostly in the later part of the night for adults.
- Learning is organised and stored.
- Irregular heartbeat and breathing in tiny babies.
- Adults woken from this sleep may be disorientated.
- More peaceful sleep.
- 50% of all sleep at birth.
- 80% of all sleep for adults.
- No dreaming.
- Slow and regular heartbeat and breathing.
- Harder to wake from.
- Occurs mostly in the early part of the night for adults.
- The immune system is boosted and physical growth occurs, you really do grow whilst you sleep.
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What are normal baby sleep cycles?
This diagram illustrates the sleep cycle of a typical six to eight-month-old.
Sleep is the main activity of your baby's brain during her early development. And these sleep-wake patterns, also know as Circadian rhythms, are regulated by light and dark.
In total, your child will typically spend 40% of her childhood asleep says the Sleep Foundation. Here's what to expect at different stages of your little one's development.
Newborns won't have developed these sleep-wake patterns yet, meaning irregular sleep schedules.
By three to six months, your baby should have a regular sleep-wake cycle.
By the age of two, your child should have spent more time asleep than awake.
As your baby grows, her sleep cycles will start to look more and more like yours.
Why does my baby wake up in the night?
All of us naturally wake during the night. Sleep problems arise when your little one is unable to get herself back off to sleep again.
Andrea says:
‘All babies wake in the night due to the sleep cycles. In the early weeks you should expect to be up in the night as your baby will need to be fed.
'It also takes a few weeks for a baby’s circadian clock to be set to sleep more at night than in the day. When a baby is newly born - and for the first few weeks - her sleep will be evenly spread between night and day.'
According to Andrea, after the age of about three or four months, the main reasons for your baby waking up and crying in the night are:
- Being over-helped to go to sleep at the start of the night, so she needs to find where you are when she wakes up later.
- Expecting some kind of ritual of contact with you either during the night or at dawn (which she thinks is night.) This could be food, a cuddle, medicine and so on.
- Discomfort, for example your baby is too hot or cold or is hungry.
How much sleep does my baby need?
There is a vast range of 'normal' and all babies are different with some needing more or less sleep than others.
With that in mind, here is Andrea's guide to the typical amount of sleep your baby needs...
AGE: 0-6 Weeks
SLEEP NEEDED: 15-18 hours in a 24-hour period
This sleep is usually spread evenly between day and night.
Sleep can seem light and fidgety as new babies experience around double the amount of REM sleep than adults do.
Your baby at this young age needs frequent feeds, and her tummy can’t cope with huge amounts of food. The numerous waking at this age are essential so your baby can be fed to her needs.
AGE: 6-16 Weeks
SLEEP NEEDED: 14 -16 hours in a 24-hour period
Sleep will be becoming deeper and lasting for longer periods.
This is partly helped by your baby’s ability to take in more food and feed less often.
It is usual for a baby of about eight-weeks-old to sleep for six hours at night without waking for a feed, although many babies have managed to do this earlier and some will be a little later.
The nature of your baby’s sleep will have changed slightly too, with a little less REM sleep and more of the “peaceful” NREM sleep.
AGE: 4-6 Months
SLEEP NEEDED: 14 -15 hours in a 24-hour period
This is typically broken up into 6- 12 hours at night, with two or three daytime naps.
Babies move into a mature pattern of one and a half hour sleep cycles and less REM sleep at around six months, with longer periods of deep sleep.
Also by six months, most babies have started solid food during the day. This means your little one is less likely to wake for a night feed, unless she come to associate feeding as a sleep trigger.
AGE: 6-12 Months
SLEEP NEEDED: 13-15 hours sleep in a 24-hour period
This is typically broken up into 10-12 hours at night plus two daytime naps.
The second nap is often dropped as babies reach one year, and just one long nap is taken. Babies of this age may also need a teatime “cat nap.”
AGE: 12 Months – 2 Years
SLEEP NEEDED: 13 -15 hours in a 24-hour period
Your little one will be having one long nap in the middle of the day.
How can I help my baby sleep better at night?
You now understand your baby's sleep cycles... but she's still not sleeping! If this sounds familiar, Andrea says:
'Exposure to day light, especially in the morning will set your baby’s circadian clock and help her to sleep better at night time.
'The contrast of lightness in the day and darkness at night helps her to produce healthy levels of melatonin, which is the hormone responsible for putting her to sleep at night and keeping her asleep.
'Not only this, but daylight exposure can also improve a baby’s mood, as it increases the release of the "feel good” hormone, serotonin.'
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