How do I know if my babies sleep is "normal"?
A new study sheds light on the normal patterns of sleep in the first months of life
If you are a parent yourself, or have ever spoken to a parent of young children, you will know it is a challenging time to say the least! No challenge is greater than the nuclear bomb your baby drops on your attempts to sleep, and managing this is a cause of huge anxiety for many families.
Many people recognise there is some natural variation to the chaotic patterns of baby sleep, but one of the most common questions we get asked as paediatricians is whether a babies sleeping pattern (or lack thereof) is, “normal”.
Now, a fantastic new study gives us one of the best tools to see just what counts for “normal” as babies sleep.
What is the study?
The new publication in the journal, “Archives of Disease in Childhood”, takes data from a the control arm of a randomised trial conducted in Ireland of massage therapy on baby sleep (the BABY SMART study), the actual results of which are awaited.
They take the sleep diary data of over 100 babies, and use a statistical analysis to create a model of the distributions of baby sleep patterns as they get older. The result is reference centiles for babies sleep from 4 to 16 weeks of life, which look similar to what most parents will be familiar with from baby growth charts!
The first thing that stands out is the huge variation in total 24 hour sleep duration at 4 weeks of age - anywhere from 7 hours to 17 hours falling within the “normal” 95% of babies (this definition of normal being somewhat arbitrary). Sadly for parents, there is somewhat less variation in the longest sleep episode duration at this age, ranging from 2 to 6 hours.
One of the most interesting things is that the median total sleep duration (50th centile) remains almost completely static over this 10 week period, at 12h. The only thing which changes as babies get older is the total variation somewhat shrinks (all outliers generally get a bit closer to 12h) and a shift mercifully comes from daytime sleep to night-time sleep - although not by much, only an extra 2 hours or so.
Finally, the variation in longest episode of sleep duration actually increases with age, meaning by 16 weeks the normal range is anywhere from 2.5 hours (God help those poor parents) all the way up to a whopping 14 hours (we’ve all met those smug idiots), although the median only increases from a measly 3.5 to 5.5 hours.
Questionnaire
There was a sleep questionnaire at 2 and 16 weeks which also included some interesting data. At 2 weeks, 95% slept in a cot in their parents room, but 25% reported sometimes co-sleeping. By 16 weeks 75% slept in a cot in the parents room, 15% in a cot in another room, and 9% in bed with the parents. At 2 weeks 49% of mothers were breastfeeding only, as compared to 31% at 16 weeks. At 16 weeks, 31% of babies fell asleep in bed alone, 30% whilst feeding and 18% whilst being held.
When asked at 16 weeks whether they thought their babies sleep was a problem, 80% responded “no problem at all”.
The major limitation of this study is that it is taken from a very homogenous cohort of Irish babies, so what we call “normal” from this study might not apply to different populations.
Summary
There is a huge variation in normal baby sleep from age 4 to 16 weeks. There is some small convergence towards a total sleep duration of 12h, with slightly more night time sleep, but increasing variation in how much sleep is concentrated in to long episodes. This data provides a useful reference point for what the range of, “normality” looked like during the early months of live, although it probably provides little relief to the parents struggling through these challenging times!