You know how good it feels to sleep well. But do you know how amazing sleep really is? If you could take a peek into what happens during sleep, you might be surprised at the complexity and the beauty of what goes on. It would also give you a lot of insight into why little ones wake so often.

What are sleep cycles?

The different stages of sleep are the key to understanding why little ones wake so often. Not teething. Not developmental stages. Not even hunger. These things might cause your little one to call for you when he wakes, but it is not what wakes him.

Sleep is made up of different types of sleep, which cycle throughout the night. You may have heard of REM sleep, which stands for rapid eye movement. REM sleep is hugely important, but we’ll get to that in a moment. Beginning around 3-6 months of age^[1]Anders, T. F., & Keener, M. (1985). Developmental course of nighttime sleep-wake patterns in full-term and premature infants during the first year of life. I. Sleep, 8(3), 173–92. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/4048734, we enter sleep through a few stages of non-rapid eye movement, or NREM.

In NREM stage 1, we’re still fairly aware of our surroundings. This stage serves as the transition from waking to sleep. It’s a very light stage of sleep; someone awakened from this stage might believe that they weren’t actually asleep. We pass through this phase fairly quickly^[2]Committee on Sleep Medicine and Research. (2006). Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem. (H. R. Colten & B. M. Altevogt, Eds.). Washington, D.C. http://doi.org/10.17226/11617: it only makes up the first 1-7 minutes of the first sleep cycle.

The next stage of NREM sleep, stage 2, makes up about 50%^[3]Ibid. of an adult’s sleep; it makes up slightly less^[4]Kahn, A., Dan, B., Groswasser, J., Franco, P., & Sottiaux, M. (1996). Normal sleep architecture in infants and children. Journal of Clinical Neurophysiology : Official Publication of the American Electroencephalographic Society, 13(3), 184–97. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/8714339 of the sleep in infants and young children. It’s still a fairly light stage of sleep, but you’re becoming less aware of anything going on around you. This stage is important for memory processing.

We’re still able to wake fairly easily out of this stage. If you were holding a sleeping baby and tried to move him at this point, baby might wake up during the transfer.

During stage 3 NREM sleep (formerly divided into both stage 3 and 4; also known as slow wave sleep), heart rate and blood pressure drop; breathing becomes deep and even. This is the deepest level of sleep, when cell growth and repair occur. Energy is restored, key hormones, like human growth hormone ^[5]Lampl, M., & Johnson, M. L. (2011). Infant growth in length follows prolonged sleep and increased naps. Sleep, 34(5), 641–50., are released. We are least aware of external activity during this stage. If forced awake, you would feel extremely groggy.

After NREM3, there is often a return to stage 2 sleep, and then a period of REM sleep when we are most likely to experience vivid dreams^[6]Purves, D., Augustine, G. J., Fitzpatrick, D., Katz, L. C., LaMantia, A.-S., McNamara, J. O., & Williams, S. M. (2001). The Possible Functions of REM Sleep and Dreaming. In et al. Purves D, Augustine GJ, Fitzpatrick D (Ed.), Neuroscience (2nd ed.). Sunderland, MA: Sinauer Associates. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK11121/. This stage is important for learning^[7]Denenberg, V. H., & Thoman, E. B. (1981). Evidence for a functional role for active (REM) sleep in infancy. Sleep, 4(2), 185–91. and memory consolidation. Adults experience about 25% of their sleep as REM sleep, but for a newborn this stage makes up 50%^[8]Bathory, E., & Tomopoulos, S. (2017). Sleep Regulation, Physiology and Development, Sleep Duration and Patterns, and Sleep Hygiene in Infants, Toddlers, and Preschool-Age Children. Current Problems in Pediatric and Adolescent Health Care, 1–13. of their sleep.

While in REM sleep, heart rate and breathing return to close to their waking rates, and the brain is incredibly active. We are able to wake pretty easily out of REM sleep. Conveniently, most of our sleep close to morning is made up of REM sleep.

So what causes babies to wake at night?

These stages of sleep normally happen in sequence, giving us distinct sleep cycles. The first sleep cycle of the night is made up of more deep stage 3 sleep than later cycles, and REM sleep dominates as we get closer to morning. Adult sleep cycles average 90-110 minutes, but infants have a much shorter cycle, lasting about 45-60 minutes.

Distinct NREM/REM cycles begin happening around 3.5 to 4 months of age^[9]Grigg-Damberger, M., Gozal, D., Marcus, C. L., Quan, S. F., Rosen, C. L., Chervin, R. D., … Iber, C. (2007). The visual scoring of sleep and arousal in infants and children. Journal of Clinical Sleep Medicine : JCSM : Official Publication of the American Academy of Sleep Medicine, 3(MARCH 2007), 201–240.. With this maturing of sleep cycles comes a periodic waking at the end of each cycle that remains a permanent part of the fabric of sleep. (This maturation of sleep is often described as the “4 month regression.”) This is why your baby may have been sleeping for longer before 4 months of age, but now is waking frequently. From this point on, everyone wakes at night.

Normally we aren’t aware of these awakenings since we return quickly to sleep. These awakenings are protective: they allow us to check on our surroundings, or to shift position so that we don’t become uncomfortable in one place for too long. Essentially, it’s what makes sleep different from a coma! For babies, these awakenings also allow them to signal to their parents when they have a need. If there’s no urgent need, baby might continue on to another cycle, repeating this light/deep/light/dreaming trend through the night.

How does trust affect sleep?

Pause for a moment with me, and imagine with me that you’re out camping by yourself, and you’ve gotten lost. You’re not sure who else is around or what to expect through the night. You can’t hold your eyes open for another moment though, and sleep overtakes you.

Would you sleep well? Probably not. Any foreign noise would put you on high alert. An animal moving by would startle you. You would resist allowing your body to go into that deep stage of sleep; the wakings characteristic of lighter sleep would give you frequent opportunities to make sure that you were still safe. Rather than quickly settling back to sleep, you would scan your surroundings to make sure everything was still okay.

What allows us to sleep well when we’re at home and in our own bed? We know what’s going on around us. We know that we’re safe. Because when you think about it, sleeping is an act of trust. You’re incredibly vulnerable when you’re asleep. You have to be confident of what’s going on around you in order to let your guard down and rest.

For your child, this world is a great big unknown. The way they learn that it’s safe to fall asleep and stay asleep is to know that nothing will change through the night as they reach those frequent periods of light sleep. How your baby falls asleep at bedtime is how he expects to get back to sleep at each waking point through the night. That consistency builds trust that it’s safe to sleep.

Remember though, that babies experience shorter sleep cycles than adults, and that it’s normal for babies to wake often throughout the night. If he needs your help to settle to sleep at bedtime, he’ll likely need your help multiple times through the night at each waking point. Committing to helping your baby fall asleep at bedtime means committing to helping your baby return to sleep. Night after night after night.

I can’t keep doing that! Is there a way out?

You’re not alone: no one can keep up with this. Not without losing your sanity, that is. We weren’t made to continue to face interrupted sleep without end.

Although caring for your newborn at night is part of being a parent, a healthy baby is capable of sleeping for longer stretches by 2-3 months of age^[10]Henderson, J. M. T., France, K. G., Owens, J. L., & Blampied, N. M. (2010). Sleeping through the night: the consolidation of self-regulated sleep across the first year of life. Pediatrics, 126(5), e1081-7. http://doi.org/10.1542/peds.2010-0976. Generally, most infants can last through the night without a feeding by 6 months of age^[11]Mindell, J. A., & Owens, J. A. (2015). A clinical guide to pediatric sleep : diagnosis and management of sleep problems (3rd ed.)., though you may choose to keep feedings as long as you or your pediatrician deem necessary.

But when your baby’s trust hinges on you being there every time sleep begins (at bedtime) or restarts (through the night), it becomes a black hole that you can never fill. You simply can’t respond so consistently that your baby decides to stop waking. Remember, those wakings are built into the nature of sleep.

This is why we teach independent sleep. By providing your baby with a consistent bedtime routine, you build predictability for your little one. He learns to expect what comes next. When we allow baby to drift off to sleep on his own instead of being fed/rocked/bounced to sleep, there are no surprises in the middle of the night. When our daytime interactions have shown baby that we are responsive as well as confident in giving baby room to grow, that trust translates into a greater ability to fall asleep at night. Your baby knows that you have provided for him, and that you see him as capable.

Guiding your little one into sleeping through the night starts with letting him fall asleep totally on his own at bedtime. He’ll still wake at night, but he’ll know how to return to sleep without needing to cry for you to help him. If he needs a feeding, you’ll know that he’s waking due to hunger instead of an inability to get back to sleep without that feeding.

Making the change to independent sleep.

If you’ve come to the point where interrupted sleep is taking a toll on your whole family, know that making the transition to independent sleep is not breaking baby’s trust in you. It’s building it. You’re showing baby that you’re confident that he is now able to settle to sleep on his own, so that there are no surprises at night.

It’s the opposite of what happens when you’re helping your little one to sleep. If you’re soothing your little one until he reaches that deep stage 3 sleep, your child is unaware that you’ve left. As baby returns to a lighter stage of sleep, it’s disconcerting to find that you’re no longer there. Your baby doesn’t know that he can trust you: you keep vanishing. It doesn’t have to stay that way though. Changing habits is challenging, but it can be done. Giving your little one the gift of independent sleep is an act of love.

Life after the change to independent sleep.

Once your baby is falling asleep totally on his own at bedtime, longer stretches of sleep will often develop on their own throughout the night, as baby gets used to navigating back to sleep on his own. Babies younger than 6 months may still need 1-2 night feedings, and some babies hang on to one feeding until closer to 9 months.

If regular night waking continues, you may need to take a closer look at what baby is relying on at bedtime to fall asleep, or what seems to be the “only” thing that will help baby back to sleep during the night. You may need to give baby some reassurance that he is capable of falling back to sleep on his own during the night as well, particularly in the first few hours when sleep is the deepest (that stage 3 sleep).

Will your baby still wake you at night from time to time? Of course. It’s developmentally appropriate for babies to continue to wake occasionally throughout the first year. Learning to roll, crawl, pull to stand, and walk all have a good chance of leading to your baby calling for you during the night, as he gets to a light stage of sleep and thinks, “I want to practice that new thing that I learned!” Illness and leaky diapers may still cause your baby to summon you from your bed: baby knows that you respond to his needs, even when he knows how to fall asleep without help.

The effort you’ve put into making your actions responsive and predictable to your baby makes a difference. You’ve taught your baby that surrendering to sleep is a good and pleasant thing, and he can trust you.