Written by: Nicky Barker, Founder of Little Ones & Paediatric Sleep Specialist In our work with mums and dads whose babies just want to party all night long, very often the only thing “wrong” is either that their baby has had too much day sleep or hasn’t had enough. Undertiredness and overtiredness are the biggest contributors to poor napping. It’s actually all rather scientific. Babies need a delicate balance of day sleep vs night sleep – too LITTLE day sleep results in cortisol (a stress hormone) building up in your baby which will make them harder to settle and also lead to night waking or early morning waking. Cortisol triggers the “fight or flight” function in babies and is like adrenaline coursing through their bodies…Impossible to sleep well under those conditions! Equally too MUCH day sleep can also lead to a lot of night waking and your baby being unsettled overnight because they just need some awake time. To put it simply, we need to look at the whole 24 hour period. Babies have a specific amount of sleep hours they can do in 24 hours, based on their age. If your baby is doing a lot of these sleep hours during the day, of course, they will sleep less at night. The goal is to find the right balance. And the balance is constantly changing as your baby gets older. It is governed by two things: awake times and nap lengths. AWAKE TIMES FOR BABIES This is the chunk of time your baby is awake for between each sleep (including feeds). If a baby’s awake times are a little too short between naps they won’t be tired enough to nap properly at the right times – this can mean they struggle to fall asleep for naps and at bedtime (because they’re not tired enough), and, if they do fall asleep, they’ll only sleep for a short time. Something we see very regularly is parents seeking our assistance because they can’t get their baby to fall asleep, assuming their baby is OVER tired, when actually their baby is UNDER tired. I know how they feel. With my second baby, knowing very little about awake times, but determined to stop him getting overtired, I was trying to put him to bed too soon for his naps every time and then wondering why he just wasn’t falling asleep. I remember getting so frustrated, upset, stressed out, convinced there was something wrong with my baby. In hindsight, he just wasn’t tired enough to go to sleep yet. Once I cottoned on to the magic of the RIGHT awake time, we were away laughing. The important thing to remember is that awake times change very quickly (especially with young babies). A brand new baby can only stay awake for around an hour at a time, yet by 3 months old this awake time has stretched to 2 hours. Many people fall into the trap of not increasing their baby’s awake times as they get older, then, like me, wonder why their baby suddenly isn’t going to sleep as easily as they did before. A baby who is good and ready for sleep at the right time should fall asleep very easily. (See THIS video for how to settle your baby to sleep under 3 months old). The opposite of under tiredness is overtiredness; keeping your baby up for too long between naps will mean they are just as hard to settle. Remember the cortisol hormone from earlier? It rears it’s ugly head if a baby is really overtired, which, completely unjustly, means your baby will then sleep worse as a result of their overtiredness. Waking after 45 minutes at bedtime, frequent night waking or early morning waking can be directly linked to a buildup of “sleep debt” during the day due to too much awake time and not enough nap hours. Which brings us to: BABY NAPS BY AGE Once you’ve got awake times sorted, you need to look at the second part of the equation, nap lengths, and check that your baby is having the right amount of nap hours to lead to a well-rested baby who wants to sleep well at night. Here is a guide to help you (allowing for 12 hours overnight): Age Daytime cumulative nap hours 2-3 weeks 5 ½ hours across 3 sleeps 3-5 weeks 5 hours across 3 sleeps 5-7 weeks 4 ½ hours across 3 sleeps 7-9 weeks 4 hours across 3 sleeps 9-12 weeks 3 ½ hours across 3 sleeps 3-4 months 3 ¼ hours across 3 sleeps 4-6 months 3 hours across 3 sleeps 6-9 months 2.5 hours across 2 sleeps 9-12 months 2-2.5 hours across 2 sleeps 12-24 months 2 hours across 1 sleep As well as meeting the total allocation of nap hours, the way those hours are divvied up is just as important. It is physiologically better for babies and toddlers to get a good chunk of sleep in one consolidated nap around midday when all humans have a natural dip in their energy levels (from 12-2pm). A long nap at this time is most beneficial to your baby's 24-hour sleep log, so if a baby sleeps for too long in their morning nap and then doesn't have a long enough nap at midday, they will be going into the afternoon and then bedtime with a greater build-up of sleep debt/overtiredness. What we commonly see in babies over 3 or 4 months old is catnapping – sleeping for only one sleep cycle at a time. This is a developmental occurrence at this age (called the 4 month sleep regression) and while some of these babies will still be meeting their cumulative daily nap hours through several 45 minute naps, they don’t have the chance to catch-up on that restorative sleep and will still be in quite a lot of sleep debt come bedtime. If your baby is in this category, helping them learn to self-settle is your best line of defence against catnapping. WAKING THE BABY FROM A NAP So to gel together awake time vs nap time, here comes the sometimes contentious part… WAKING THE BABY. While it might seem very counter-instinctive (or downright mean) to wake a sleeping baby, we do advise doing it if your baby is at risk of having had too many daytime sleep hours, or of sleeping for too long in the morning nap which will mean their lunch nap is consequently shorter, or if they're sleeping too late or long in the afternoon which will have a negative impact on their bedtime settling and nighttime sleep. I always hold to the mantra “it is better for you to wake your baby in the day rather than your baby wake you in the night”. Some babies are better day sleepers than others. My youngest is like this. She would quite happily snooze the day away and then party all night. Because I have 2 older children and a pretty busy day-to-day life, I’m not okay with this! For me, being in control of her daytime sleep hours is really important to ensure she sleeps well at night. It’s a balance. And sometimes it is really tricky to get it right. Here's a video addressing why your baby won't nap: Why won’t my baby nap at all? from Little Ones on Vimeo. To take the guesswork out, we have designed our age-appropriate Sleep Programs around the ideal nap times and awake times to make sure your baby is getting the perfect sleep combination, allowing them (and you!) to get a whole lot more sleep. Imagine that! Download our FREE Newborn Sleep Guide for loads of helpful info about newborn sleep. CLICK HERE to download your FREE Baby Sleep Journey Chart! Download our FREE Baby Sleep App: If you liked this blog, be sure to check out Sleeping Like a Baby and The most common baby sleep myths for more sleep advice. ___________ Bibliography Horváth, Klára, and Kim Plunkett. “Frequent daytime naps predict vocabulary growth in early childhood.” Journal of child psychology and psychiatry, and allied disciplines vol. 57,9 (2016): 1008-17. doi:10.1111/jcpp.12583 de Weerth, C., R.H. Zijl, and J.K. Buitelaar. Development of cortisol circadian rhythm in infancy. Early Hum Dev. 73(1-2): p. 39-52. 2003. Gunnar, M.R. and B. Donzella. Social regulation of the cortisol levels in early human development. Psychoneuroendocrinology. 27(1-2): p. 199-220. 2002. Middlemiss, W., D.A. Granger, W.A. Goldberg, and L. Nathans. Asynchrony of mother-infant hypothalamic-pituitary-adrenal axis activity following extinction of infant crying responses induced during the transition to sleep. Early Hum Dev. 88(4): p. 227-32. 2012. Scher, A., W.A. Hall, A. Zaidman-Zait, and J. Weinberg. Sleep quality, cortisol levels, and behavioral regulation in toddlers. Dev Psychobiol. 52(1): p. 44-53. 2010. Abulizi, Xian et al. “Temperament in infancy and behavioral and emotional problems at age 5.5: The EDEN mother-child cohort.” PloS one vol. 12,2 e0171971. 15 Feb. 2017, doi:10.1371/journal.pone.0171971 Galland, Barbara C et al. “Anticipatory guidance to prevent infant sleep problems within a randomised controlled trial: infant, maternal and partner outcomes at 6 months of age.” BMJ open vol. 7,5 e014908. 2 Jun. 2017, doi:10.1136/bmjopen-2016-014908 Mindell, J. A., Leichman, E. S., Composto, J. , Lee, C. , Bhullar, B. and Walters, R. M. (2016), Development of infant and toddler sleep patterns: real‐world data from a mobile application. J Sleep Res, 25: 508-516. doi:10.1111/jsr.12414 Molfese, Victoria J et al. “Relations Between Toddler Sleep Characteristics, Sleep Problems, and Temperament.” Developmental neuropsychology vol. 40,3 (2015): 138-54. doi:10.1080/87565641.2015.1028627
