Baby sleep patterns & baby sleep regressions

Babies and adults have different sleep patterns

Young babies have shorter sleep cycles than us adults, theirs are about 40 minutes and ours are about 90 minutes.  Babies spend more of their sleep cycle in REM sleep.

This is important because it’s during REM (light/dream) sleep that brain development happens, the blood flow to the brain almost doubles during REM sleep. This shorter and lighter sleep cycle is thought to also help protect infants from SIDS.

There are some significant changes that happen to the sleep cycle architecture (sleep cycle, length of sleep, and depth of sleep) when babies are approximately 3-6months (commonly 4 months) when they develop a more mature sleep cycle.

The Newborn sleep cycle matures from this:

REM – NREM3/4 – REM – NREM3/4 

To this more mature adult cycle:

NREM1 – NREM2 – NREM3/4 – NREM2 – NREM1 – REM – NREM1 and so on..

More mature babies will spend less time in REM sleep and more time in NREM sleep as they get older. There are 4 stages of NREM sleep. NREM could be described as the brain’s way of slowly ‘changing gears’ into a deeper state of sleep.

Features of the different stages of sleep

REM – [Rapid Eye Movement] Lighter/dream sleep

• Consolidating thoughts, brain growth and synaptic pruning
• Converting short-term memory to long term memory
• Easily woken
• Body is immobile and relaxed
• Nightmares may occur

NREM 1&2 [Non Rapid Eye Movement] Light sleep/ falling asleep

• Easily woken, transient thoughts are experienced
• Body is calming down
• Can experience hypnic jerks, when the body twitches
• Children need less stage 1 and 2 sleep than adults

NREM 3&4 . Deep sleep / Slow wave sleep (SWS)

• Hard to wake, resting, restorative sleep
• Cell growth and repair, growth hormone is released
• Night terrors, tooth grinding, sleepwalking, bedwetting might occur
• Breathing is slower and blood pressure drops
• Increased blood supply to muscles

What is a sleep regression?

The definition of Regression is “to return to a former or less developed state”, so when people talk about a sleep regression they are often meaning their baby is waking up more often, similar to when they were younger.

The most talked about sleep regression is at 4 months.  Here is why.

As mentioned above, a baby and an adults sleep cycle looks very different.  A baby’s sleep cycle will mature approximately between the ages 3-6 months and very often it occurs at 4months old.  This change can be unsettling for little ones as they start moving into a more adult sleep cycle. So their sleep hasn’t actually regressed, it’s matured, but along with this change can temporarily bring with it more wake ups.

Maturation of the sleep cycle isn’t the only reason sleep can change. Sleep regressions (which can include frequent waking/nap refusal/ shorter naps and overall sleep duration) are noticeable around times of increased development – for example, rolling, talking, crawling, or some separation anxiety. Common times for these developmental leaps will be 4, 8, 12 and 18months when something big is going on for them.

Sleep regression/ frequent waking can take it’s toll on a family.  Do remember that baby hasn’t suddenly forgotten how to sleep and they aren’t going backwards with their development, actually the opposite is true as you’ve read above.  They are progressing with their development but sleep has become the collateral for this.  It is only temporary. It is normal.  Keep going with your sleep hygiene and healthy habits, give them love and hold them close, help them feel secure during these bumps and look after yourself too.