Do you think your baby is afraid of the dark? Or does your toddler refuse to sleep in pitch-black darkness because of the monsters under the bed? You might think that cute little night lights are the best solution and that their warm glow will help your sweetie sleep better.

In reality, the effect of night lights on your child’s sleep is quite the opposite.

A recent study published by the Journal of Pineal Research found that night lights can prevent your child from falling asleep, and deter them from staying asleep.

But not every night light is created equal—experts weigh in on what to look for and share the science behind how they impact your little one’s sleep.

Read on for a science-backed explanation of how they affect your little one’s sleep.

Is your baby afraid of the dark?

A common fear among parents is that their baby might be afraid of the dark, and a night light would help them feel safe. Rachel Mitchell, Certified Sleep Specialist, and CEO of My Sweet Sleeper, dispels this myth: “Babies do not develop these types of fears at such a young age, so this is typically not something that parents need to worry about.”

However, this might not hold true for your toddler. By two years of age, children develop cognitively and have a curious, vivid imagination. So a pitch-black room might be scary for them.

How do night lights affect babies?

Light affects sleep differently for adults and babies.

As adults, we have a fully-formed circadian rhythm. When our eyes detect sunlight, they signal our brain to release cortisol, a hormone that helps us stay active and alert. Similarly, when the sun goes down, our eyes pick up the absence of white light, signaling our brain to release melatonin, a hormone that makes us sleepy and prepares our body for rest. 

It’s a different ballgame for little ones.

For the first three months after birth, your little one cannot distinguish between day and night. Their body doesn’t naturally produce cortisol in the morning and melatonin when it gets dark. Instead, they get these hormones from breast milk.

As your little one is exposed to more direct natural sunlight during walks, or while napping in their Cradlewise in front of a window, their body slowly begins to learn the difference between day and night. However, exposure to bright lights and screens at home, along with night lights, can act as a roadblock in this fundamental process.

Around four months of age, babies start to produce melatonin, the sleepy hormone that helps to promote long stretches of sleep at night. “In order to help melatonin do its job, it is important to create a low stimulation environment for your baby by dimming the lights and ensuring they are not exposed to any blue lights from screens,” Mitchell says.

How does the intensity of light affect baby’s sleep?

The intensity of light you are using plays a significant role in how it affects your baby—not just the color and brightness, but also the other lights they might be exposed to, especially during the hours before their bedtime.

“The effect of night lights on babies varies depending on the age of the child and how sensitive they are to light. A small night light might be fine for some children, but too overstimulating for others, and could prevent them from getting restful sleep,” Mitchell states.

So how can you tell whether your baby’s night light is causing sleep problems?

“If you notice that your baby is waking up a lot at night or having a hard time falling asleep and you are using a night light, this could be an indication it is too stimulating for them,” Mitchell suggests.

How do night lights affect toddlers?

A recently published study by the Journal of Pineal Research was conducted on 36 three to 5-year-old children, measuring the effect of exposure to light before sleeping.

The children in the study wore a wrist monitor to track their light exposure and sleep quality for nine days. Before the experiment, the kids’ parents kept them on a stable sleep schedule (this normalized their body clocks and ensured their melatonin levels rose consistently each evening).

The findings on how light exposure and night lights affect how toddlers sleep were astonishing.

Scientists found that, unlike adults, the light intensity doesn’t matter when it comes to melatonin suppression in young children. Both dim and bright lights had a similar effect on the melatonin levels of the children who participated in the study.

When suppressed through exposure to night lights, it can lead to problems like bedtime resistance and sleep onset delay.

In a statement released by the University of Colorado, Monique LeBourgeois, Ph.D., senior author of the study, says that “Kids are not just little adults. This heightened sensitivity to light may make them even more susceptible to dysregulation of sleep and the circadian system.”

According to LeBourgeois—an associate professor of integrative physiology who has studied circadian biology in young children—genes can also play a significant role in influencing light sensitivity in children. “They may be more sensitive to light than other children. In that case, it’s even more important for parents to pay attention to their child’s evening light exposure.”

But this doesn’t mean you need to ban night lights altogether. After reviewing the study, Dr. Norman Sheldo, O.D., from the Eyecare Center of Maryland, put the findings in context.

“If the light is greater than a certain threshold, melatonin levels will be affected, possibly interfering with sleep. The study determined 1.5 lux [lux is the unit of measurement of light level intensity or illuminance] is okay. 5.0 lux is not. We don’t know the effect between 1.5 and 5.0 because it wasn’t studied. Very dim lights 1.5 lux or less will not affect children’s sleep.”

So according to Dr. Sheldo, “In summary, very dim red night lights will almost certainly not affect sleep for young children.”

How does the anatomy of children’s eyes differ from adults?

The eyes of babies and toddlers process light much differently than us adults. According to Dr. Sheldo, “The pupils of babies are larger than those of adults.”

The same also holds true for toddlers’ pupils. Plus, their lenses are more transparent than those of adults. These two things mean that when there’s a flow of light, their eyes can’t stop it as well as an adult’s eyes can.

So if your toddler is exposed to a bright light an hour before bedtime, the effect on their sleep will be the same as when they are exposed to a dim night light in their room.

Dr. Molly O’Shea (MD), the Founder of Birmingham Pediatrics, says, “Infants, even though their vision is poor for discerning things, see light quite well. All color wavelengths except red will interfere with melatonin release at all ages, even if babies can discern color yet. By interfering with that, a sense of wakefulness can persist longer than it should.”

The bottom line

Sleeping in the dark facilitates the body’s natural production of melatonin, which helps your little one fall asleep (and more importantly, stay asleep). If your child prefers a night light, opt for a dim red-based one so as not to interfere with their sleep cycle.

Want to know how you can create a safe sleep environment for your kiddo? We have compiled a list of 10 tips for sleep-friendly lighting.

FAQs

Q: Is it better to sleep with or without a night light?

A: It is better to sleep without a night light, especially if it’s a blue-based night light. Light exposure in the hours leading up to bedtime and during sleeping hours can hinder your body’s natural melatonin production, making it difficult for you to fall asleep.

Q: How do I know if my toddler needs a night light?

A: If your toddler is telling you that they are afraid of the dark and won’t sleep in their pitch-dark room, they might need a night light. However, make sure you buy a red-based nightlight for their room.

Q: Should kids sleep in total darkness?

A: It’s better for kids to sleep in total darkness as it promotes melatonin production in their bodies, which helps in falling and staying asleep. However, if your kid is afraid of the dark, you can used a red-based nightlight.

Q: What’s the best color night light for sleeping?

A: Red-based night light.

Sources:

1. Effect of light on human circadian rhythm. The Journal of Biological and Medical Rhythm Research. 2018. “Systematic review of light exposure impact on human circadian rhythm.”
2. Study on night lights. Wiley Online Library. 2022. “High sensitivity of melatonin suppression response to evening light in preschool-aged children.”