The Neuroscience of Being Human
The Neuroscience of Toddler Sleep
Why the toddler brain resists sleep with such determination, what is happening neurologically during the nap transition, and why the bedtime battles that exhaust parents are the predictable output of a brain that is too busy building itself to want to shut down
888-word article with 8 Harvard references.
Key takeaways
- The toddler brain requires significantly more sleep than the adult brain, approximately eleven to fourteen hours per twenty-four-hour period, because sleep is the state in which the brain consolidates learning, processes emotional experiences, prunes unused synapses, and produces the growth hormone that supports physical and neural development. Sleep is not a pause in development. It is when much of the development actually happens (Mindell et al., 2006).
- The toddler circadian system is still maturing, and the internal clock that regulates the timing of sleep and wakefulness is easily disrupted by light exposure, inconsistent schedules, and the developmental changes that alter sleep architecture between the ages of one and three.
- The nap transition, from two naps to one and eventually from one nap to none, is a neurologically significant event that produces a period of instability during which the toddler is too tired for one nap but not ready for the sleep pressure that accumulates without one. The transition is gradual, messy, and not linear.
- Bedtime resistance in toddlers is driven by multiple neurological factors: the drive towards autonomy that is characteristic of prefrontal development at this age, the fear of separation that reflects the activation of the attachment system at the moment of greatest vulnerability, and the difficulty the immature brain has in transitioning from the high arousal of daytime activity to the low arousal required for sleep onset.
- Consistent bedtime routines work because they provide the toddler brain with predictable cues that activate the parasympathetic nervous system, reduce arousal, and create a conditioned association between the routine and the onset of sleepiness. The routine is not merely a parenting strategy. It is a neurological primer that trains the brain to begin the physiological processes of sleep onset.
The brain that is too busy to sleep
To the toddler brain, sleep is an interruption. The waking world is full of things to explore, people to interact with, objects to manipulate, and language to acquire, and the brain that is in the middle of forming seven hundred synaptic connections per second does not want to stop. The resistance to sleep that parents experience is not defiance. It is the output of a brain that is maximally engaged with its environment and does not yet possess the metacognitive ability to recognise that it is tired. The toddler who is rubbing their eyes, yawning, and becoming increasingly irritable genuinely does not know they are tired, because the ability to monitor and interpret one's own internal states, a function of the insular cortex and the prefrontal cortex, is still developing.
Jodi Mindell at Saint Joseph's University has spent decades studying paediatric sleep and has documented the developmental trajectory of sleep regulation in early childhood (Mindell et al., 2006). Her work shows that the establishment of healthy sleep patterns requires the maturation of at least three systems simultaneously: the circadian system, which regulates the timing of sleep; the homeostatic system, which builds sleep pressure in proportion to the duration of wakefulness; and the behavioural system, which encompasses the learned associations and routines that facilitate the transition from wakefulness to sleep. In the toddler, all three systems are still maturing, which is why sleep problems peak during this developmental period.
The nap that refuses to die gracefully
The transition from two naps to one, which typically occurs between twelve and eighteen months, and the subsequent transition from one nap to none, which typically occurs between three and five years, are neurologically significant events that produce weeks or months of instability. The instability occurs because the sleep pressure system, which builds adenosine in the brain in proportion to wakefulness duration, must recalibrate to accommodate the longer wake windows that the nap elimination produces. During the transition, the toddler accumulates too much sleep pressure for comfortable wakefulness but not enough for the single consolidated nap to be restorative, producing the paradoxical state in which the child is simultaneously too tired and unable to sleep.
Invitation to reflect
If you are battling a toddler at bedtime, the neuroscience offers you something that Instagram parenting advice frequently does not: an explanation that locates the problem in neurodevelopmental timing rather than in your competence as a parent. The toddler is not resisting sleep because you have failed to establish boundaries. They are resisting sleep because their brain is immature in precisely the ways that would need to be mature for them to cooperate willingly with the process of falling asleep. They cannot monitor their own fatigue. They cannot inhibit the drive to continue exploring. They cannot manage the separation anxiety that arises when the lights go out. They cannot transition from high arousal to low arousal without external support. Everything that sleep onset requires is everything that the toddler brain cannot yet do alone. This is why the bedtime routine works. Not because it is magic, but because it is a predictable sequence of low-arousal activities that the parasympathetic nervous system learns to associate with the onset of sleep. The same bath, the same pyjamas, the same book, the same song, the same sequence, night after night, teaches the brain to begin the physiological preparation for sleep before the toddler has consciously decided to cooperate. The routine does the work that the prefrontal cortex cannot yet do. Be patient with the process. The brain will catch up. It always does.
References
- Mindell, JA, Kuhn, B, Lewin, DS, Meltzer, LJ and Sadeh, A (2006) Behavioral treatment of bedtime problems and night wakings in infants and young children. Sleep, 29(10), pp. 1263–1276.
- Jenni, OG and LeBourgeois, MK (2006) Understanding sleep-wake behavior and sleep disorders in children: the value of a model. Current Opinion in Psychiatry, 19(3), pp. 282–287.
- Sadeh, A, Mindell, JA, Luedtke, K and Wiegand, B (2009) Sleep and sleep ecology in the first 3 years: a web-based study. Journal of Sleep Research, 18(1), pp. 60–73.
- Galland, BC, Taylor, BJ, Elder, DE and Herbison, P (2012) Normal sleep patterns in infants and children: a systematic review of observational studies. Sleep Medicine Reviews, 16(3), pp. 213–222.
- Dahl, RE (1996) The regulation of sleep and arousal: development and psychopathology. Development and Psychopathology, 8(1), pp. 3–27.
- Kurdziel, L, Duclos, K and Spencer, RMC (2013) Sleep spindles in midday naps enhance learning in preschool children. Proceedings of the National Academy of Sciences, 110(43), pp. 17267–17272.
- Touchette, E, Petit, D, Seguin, JR, Boivin, M, Tremblay, RE and Montplaisir, JY (2007) Associations between sleep duration patterns and behavioral/cognitive functioning at school entry. Sleep, 30(9), pp. 1213–1219.
- Weissbluth, M (2015) Healthy sleep habits, happy child. 4th edn. New York: Ballantine Books.
About the author
Gareth Strangemore-Jones, MHFA, DCST, PDPCP, HPD, DSFH, DMH, AHD, NCTJ, MSC-CPA, PGCE (FE) I & II
MNCPS (Reg.), MNCH (Reg.), MCNHC (Reg.), MAfSFH (Assoc.)
PSA (Acc.), FSE (Fellow), IFfS (Assoc.)
Mental Health First Aider, Pluralistic Counsellor, Clinical Psychotherapist. Consultant Medical Hypnotherapist, Mindfulness Teacher. PGCE-Trained Teacher, Lecturer, Corporate Trainer, Workplace Wellbeing Consultant. PR & Marketing Consultant, Psychology & Behaviour Advisor. Author, Journalist, Broadcaster. Advocate for Mental Health, People & Planet
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