Sleep Cues: 6 Scientific Signs Your Child is Ready for a Snooze

by Myra Hartzheim
A pediatric sleep consultant holds a baby that keeps waking in the night

What are up with sleep cues anyway? Imagine you have a movie to get to…you have between when the previews start and end to get there by the time the movie starts or you will be missing very important parts of the storyline. Believe it or not, this is similar to sleep. Our bodies are primed to sleep at specific times and you have a small window of time to begin getting your little one to sleep before you miss a very important and restorative part of sleep. Also, just like the movie, if you get there late and miss part of the movie, it doesn’t get made up by staying late for the credits, right? Same with sleep: just because your child sleeps long after starting a nap late, the child does not make up important sleep by sleeping longer. That extra sleep is often just that – extra sleep. This week I will be posting about sleep cues that will help keep you from missing those very important sleep times.

There are several physical signs that our body shows when we are getting close to needing to sleep. All of these signs are triggered by the brain but manifested in different parts of the body, which are: the eyes, the mouth, our exteriors, and behavior. I will break down common sleep cues.

Adenosine (Sleep Pressure)

When we become tired, Adenosine (sleep pressure) builds up and signals to the brain to begin relaxing our brain and muscles without substantially impairing their abilities.1

For this reason, all of the muscles in our bodies will be moving more slowly.

Sleep cues to look for in your little one

  • Slowing down in play
  • Slower motions in general
  • Sucking is weaker or slower
  • Less Vocal
  • Quieter
  • Calmer


Think of the brain as a computer processor, handling millions of calculations. Recent studies suggest that when our brains begin to overheat we begin to yawn. One reason our brains overheat is when we need to re-set and sleep. Little ones younger than 6 months of age are creating 700 synopses a second and their brains are growing at exponential rates! Heat will undoubtedly be building up in our little one’s head. So next time your little one yawns, don’t wait for the second yawn to put him to sleep.

Nerd Session

Neurons require several orders of magnitude more energy than do our other cells; the power consumption of a single central neuron is about 300–2500 times more than the average body cell.2

Since all energy used for brain metabolism appears to be ultimately transformed into heat,3

intense heat production appears to be a leading feature of brain metabolic activity.

Zoning out

When in infancy, the world is such a new place. Everything is new. Our senses begin to develop inside the womb and finish developing outside of the womb. Can you imagine how overwhelming getting used to the world can be for a new little one?! For these reasons, even just a little bit of wake time can be enough stimulation for a new person. One of the mechanisms the human body has to protect itself from becoming overwhelmed by external stimuli is to zone out.

Zoning out – otherwise known as a dissociation state – is a protective mechanism called up by the nervous system when it reaches its maximum capacity to process stimulation (both internally and externally).4

When you see your little one begin to zone out, that is a good time to begin helping your little one get some shut-eye.

Glossy eyes

When our body becomes tired, it begins to prepare for sleep by reducing hydration in our eyes. For this reason, you may notice your child’s eyes having a glossy appearance.5

Since your baby’s body is preparing for sleep, you should also help your baby do the same.

Suckling and Caressing

Both lips and fingers are believed to have the most concentration of touch receptor cells in the body. Additionally, more brain power is spent translating touch sensations from the lips and fingers than from other areas of the body that have touch receptor cells.6

It’s no wonder babies like to put things in their mouths!

Touch processing is very closely associated to emotional regulation which can also influence healing and reduction of anxiety and tension.

The exact mechanism of WHY sensory stimulation to the mouth and fingers is so soothing to many little ones is not clearly understood. But what is known is that sensory stimulation to the mouth and fingers IS very calming for many little ones, helping bring little ones to the next level of calm which often results in sleep.

Sleep cues to look for in your little one
  • Caressing “lovey” (or security object)
  • Nursing cues
  • Wanting a pacifier
  • Chewing or sucking on their hands or an object can be a cue for sleep

Seeking proximity to caregiver7

Kids are smart and know that parents are often their source of sleep or the way they get to the crib or bottle….they know who to come to in order to get that sleep. For these reasons, children often seek proximity when they are tired and ready to sleep. There are scientific reasons for this…Touch causes a release of the “cuddle hormone,” oxytocin, which buffers stress in the body and allows the body to relax into sleep more easily. While being held, the parasympathetic nervous system (“relax and repair” state of mind, as opposed to “fight or flight”) lowers the heart rate, helping the child into the next level of calm = sleep.

Challenges to Sleep Cues

1. Because we are each so beautifully unique, sleep cues can be different for each child. Watch closely and learn your child.

2. With alert children, I find their bodies and minds are so engaged with the world that sleep cues don’t even happen until too late. By the time they cue for sleep their bodies have already started into another wake cycle. In these cases, we still let the sleep cues initially guide us as to when the body seems to be ready to sleep, but undershoot that time with the help of the clock. In other words, as you get to know your child’s sleep cues, you can see when they typically happen during a day/night; then get in the habit of starting bedtime routines 15 minutes earlier than that. If I went solely by sleep cues for my kids I would be missing their sleep windows every time. Keep this in mind when dealing with a very alert child.

3. Lastly, as you can imagine, when a child is overly tired we can get skewed signals as to when they are ready to sleep. They may be tired one second and be bouncing off the wall the next. This is due to the nature of a stress (overtired) cycle. The best thing to do in these situations is to follow age-appropriate wake windows as cues may be misleading.


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One comment on “Sleep Cues: 6 Scientific Signs Your Child is Ready for a Snooze”

  1. This is so well written and I appreciated that you talked about “alert” children. That is definitely the category that my daughter falls into. You have such a soft but informative approach!

A pediatric sleep consultant holds a baby that keeps waking in the night


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