When you bring a newborn home, there’s a swirl of new questions — feeding, sleep, soothing, bonding. But one thing parents rarely think about is the light their baby experiences. Yet research shows light may be one of the most powerful signals shaping your baby’s developing sleep–wake patterns.

A fascinating study published in the Journal of Advanced Nursing tracked how light exposure helped newborns establish a healthy circadian rhythm — that natural daily rhythm guiding sleep, wakefulness, hormones, and even social development. By supporting your baby’s circadian rhythm with the right light–dark cues, you might help them settle into calmer days and more restful nights.

Why Light Matters to Your Baby

Your baby was protected in the womb, where the mother’s rhythms provided cues about day and night. In fact, there is some evidence out there that whilst being inside the mother, the type of light that is able to penetrate is not just important for circadian cues, but also impacts the wavelength of light that is able to reach the baby. For example, blue, shorter wavelength light is only able to reach the baby very late on in pregnancy once skin and tissue has been stretched. This blue light helps with skin development. Before that, it is mostly longer wavelength light red and infrareds that are able to penetrate and help the baby's formation.

Once born, your newborn’s own circadian “clock” starts developing, but it’s fragile, very fragile. A consistent day–night pattern of light exposure is the strongest external signal to train that clock.

The study followed 22 healthy infants between 2 and 10 weeks old, wearing a light and activity monitor. Results showed that even moderate levels of daylight — around 100 lux, similar to a bright indoor room — helped strengthen the baby’s daily activity and rest cycles. I would always suggest brighter light than that to build the contrast between light and dark as much as possible. Before anyone says it, I'm not saying blazing sunshine 100000Lux! I'm suggesting outside in the natural shade of a tree.

Let go back to the study. The more time babies spent in bright daytime light, the stronger their 24-hour activity rhythms became. In other words, babies who got consistent daytime light were better at knowing when to be active and when to rest. That’s a gift not just for your baby, but for you — because a baby with a more regular rhythm helps parents rest, too.

What Happens Without These Light Signals?

If a baby spends too much time in dim light during the day, their internal clock can become confused. We have all done it - not opened curtains for ages and all of a sudden it is later in the day and we are still feel groggy and lethargic. Your baby is the same, just more sensitive. Their rest–activity patterns may stay fragmented or delayed. That can mean longer stretches of unsettled sleep, more night waking, and tired parents.

The researchers highlighted how modern homes — with drawn curtains, artificial lighting, and less time outdoors — can leave babies in relatively dim environments. That’s a major shift from how humans evolved with outdoor sunlight patterns.

Newborns, the study suggests, thrive when parents help them distinguish daytime from nighttime.

How Can You Support Your Baby’s Light Environment?

Here’s what you can do:

• Maximize natural daylight during the morning and early afternoon. Open curtains wide and spend time near windows.
• Get outdoors with your baby when possible, even for short walks.
• Keep evening lighting dim and warm-toned to cue your baby that night is for rest.
• Aim for moderate brightness indoors during the day — at least 100–300 lux which is roughly what a well-lit room or shaded outdoor spot provides. The lighting should be as natural as possible.

If you live in a place with long dark winters, or you simply can’t get enough outdoor time, consider using high-quality artificial light that mimics natural daylight. At the very least, get outside with your baby, purchase a few incandescent bulbs and then look at improving your internal home environment lighting.

I, Dominic Lamb, founder of Home Light Therapy, am deeply passionate about helping families harness the science of light to support healthy biology — for both parents and their babies. I believe that understanding and using the right light at the right time gives your family a better foundation for sleep, energy, and wellbeing.

What About Preterm or NICU Babies?

Preterm infants and babies who spend time in neonatal units may have disrupted light–dark cues. Hospital lighting can be artificial, continuous, or unpredictable. I am of the opinion that improving the light environment of some NICU wards might actually help the quality and speed of outcomes. If you find yourself in that situation, it could be worth discussing with your doctor. At least there are Studies on NICU babies that have shown that introducing a clear cycle of brighter daytime light and darker nights helps these babies develop more robust circadian rhythms, too. 

If your baby was preterm or stayed in intensive care, the same principles still apply once you get home. Gentle daytime light exposure, a clear difference between day and night, and predictable lighting patterns can help their delicate clocks catch up.

A Small Change, a Big Difference

Think of light as a language your baby understands before they understand anything else. You don’t need to force a strict schedule or buy complex gadgets — simply aligning your baby’s day with brighter, active periods and your night with calm, dimmer lighting can help everyone sleep more soundly.

As your child grows, those healthy circadian patterns become building blocks for learning, mood, and long-term wellbeing.

Ready to Rethink Your Light?

Whether you’re arranging your nursery, planning a daily walk, or just wondering how to support your own rest, take a moment to consider your light. The patterns you shape today can guide not only your baby’s rhythms, but your family’s health in the weeks, months, and years ahead.

If you’d like more guidance, or you’re curious about circadian-friendly lighting solutions, visit me at Home Light Therapy — where light supports life.