It sounds super obvious: healthy sleep is fundamental to a baby’s development. However, the trouble is the way healthy sleep and healthy sleep patterns develop is looking more vulnerable based on some of our modern ways of life. So, as always, we take a look at the science to understand how these all important circadian rhythms develop in a baby, how they could potentially be disrupted and most importantly some tips and tricks that you can use to help this process along.

When I first had my son – one of the first question most people would ask me:

‘is he sleeping?!’ (Usually said with a grimace/sense of impending doom…)  

Two bits of good news here:

One: the awake every four hours thing doesn’t last forever (promise)

Two: wanting it to ‘normalise’ this as quick as possible is not as selfish as it sounds, as the quicker and more stable a circadian rhythm in a baby is established – the better – and in fact research has shown that establishing this firmly can have significant long term positive health implications for a child.

The not so good news (always a catch!)

Unfortunately, our modern lives are making this harder; delaying it and potentially even leading to future long term health issues physically and mentally and even potentially linking to SIDS (aka cot death) (2) click here for more.

Seriously?!

I hadn’t’ appreciated this until I had a very interesting conversation with one of our expert advisors Tajinder Deoora who told me that artificial light and particularly the blue light that surrounds us all a lot more is starting to have a real impact and potentially even delaying the onset of normal circadian sleep rhythms in babies.

Today’s article is a look what is happening, how it works, and most importantly how with some very little tweaks/new found consciousness you can ensure your own child’s sleep rhythm is established, protected and preserved. All contributing to a solid base and foundation for future health, learning and development.

(The cheat sheet is here – but read on for all the juicy detail!)

So, what is happening? Where is this disruption coming from?

We all know that the way our world is lit has fundamentally shifted in the 130 or so years since the invention of the light bulb. In many ways for the better of course. That being said, it has contributed to our new 24/7 lifestyles which continues apace with satellites now detecting yearly increases in artificial light at night from space.

The problem with this is that one of the most important factors that help set and establish a baby’s own circadian rhythm is light and that too much of it at the wrong time can knock the appropriate development of this rhythm off course (2):

‘Light is key to synchronise the internal clock to the external environment’ (7)

Once again, research is also suggesting that establishing this correctly is not just important for our own beauty sleep but that ‘‘long-term health consequences are related to the infant’s appropriate establishment of circadian rhythm’. (2)

So what exactly is a circadian rhythm and why is it so important?

‘Circadian rhythm is the approximate 24 hr cycle of change in the physiology of life’ (2)

In a nutshell: Most of us probably think of sleep when we think of circadian rhythms, but the truth is these rhythms apply to a lot of other things in the body too. Hormones like Cortisol and Melatonin (more on this to come) have a circadian rhythm during the day for example (starting at one level at the beginning of the day and ending at another), as does the core temperature of our body. Research even suggests that it has an influence on when you go into labor with the ‘timing of the onset of labor and birth in humans influenced by the circadian cycle with peak incidences between midnight and the early morning.’ (11)

‘Increasing evidence indicates that the circadian timing system is a fundamental homeostatic system that potentially influences human behaviour and physiology throughout development.’ (1)

In a nutshell: it controls a lot of very important functions in our bodies. So ensuring a baby is given the best possible chance to establish this is key.

So when does this start to develop?

When you’re pregnant, your baby has a loose rhythm of sleep-wake somewhat linked to your own, however, this only really develops on its own postnatally ie. when the baby is born and research has shown that how this happens is important for future mental and physiological health and that ‘the imprinting effects on the circadian rhythm of the newborn persist into adulthood.’ (2)

So, how this develops post birth is important…

The centre of this – or the control room – is the Suprachiasmatic Nuclei (SCN) in the hypothalamus. Sounds complex, but in a nutshell this is the site of the biological or ‘body’ clock. In a full term baby its development is around 20% of what an adult’s is, taking until about a year old to develop the remaining 80%. (11)

Once again, several studies have shown that one of the most powerful factors determining its development is light. In fact, light has been shown to actively change the pathways involving the suprachiasmatic nucleus in the brain (1) and is mainly set by the light/dark cycle.

This is key: not only will the postnatal light environment programme circadian behaviour, it has an influence on many other things as a knock on including cell morphology and what is known as the ‘clock gene function’ within the SCN. Developing this properly is important for future health and several studies have shown that the postnatal environment – particularly light – exerts a major and long lasting influence on the individual’s circadian system later in life. (6) So, getting it right early, can be a very positive thing for future health.

Translation: establishing a regular and solid circadian rhythm can be very powerful positively for both mental and physical development of a baby.

All important for development:

Research has shown that a proper sleep cycle and circadian rhythm can positively contribute to brain development, our ability to learn, our attention, social communications, language development memory, emotions and reducing our propensity and vulnerability to anxiety and psychiatric disorders that are all seemingly on the rise. Getting it wrong can of course lead to the reverse….. (6)

Ok so we get the fact it’s important, so how does it develop in a natural way?

Traditionally we see the sleep-wake cycle established in a baby in the first 2-4 months of life. Typically we see the rhythm of temperature develop first (a dip in body temperature before sleep and a small rise before waking), next you see the melatonin (the hormone that triggers sleep) and the sleep-wake rhythm develop from around day 30 plus (up to day 150).

What’s important is how artificial light exposure can affect this:

One study looked at the impact of maximum exposure to natural daylight and no artificial light (to be clear very hard to do in real life and not what we are advocating!!). The conclusion was that this potentially enhanced the ‘earlier and more robust appearance of entrainment in human infants.’ (1) With rhythms established around day 30 vs day 112 on average….

So clearly you can see that in order to establish this cycle quicker and in a more robust way, you want a baby’s light exposure to be as close to ‘natural’ as possible ie. lots of bright natural light during the day and darkness before and during bedtime.

Sounds simple right? Well…there are some equally surprising to fall in to pitfalls….

First and foremost with all the will in the world, there aren’t many people who will not turn on an electric light at 5pm in the winter, nor am I suggesting that is the way to go. (Phew!) The reality is we have moved on, and often for the better – it all comes down to degrees however, and this is where we can get caught out/do better…

Not all light is created equally:

Light has different frequencies and not all wavelengths are equally disrupting. The one you want to watch for the most, particularly ahead of bedtime, is the shorter wavelength blue light which ‘seems to be more disruptive at night, and induces the strongest melatonin inhibition.’ (10)

The trouble is that blue light is on the rise. Why? It is present in energy efficient lighting (LEDs) and electronic devices – which is why everyone tells you to stop using phones/tablets/TVs before bedtime. I’m assuming your newborn isn’t scrolling through instagram before bed (!) but, for a young baby if you have the TV on, bright LED lights everywhere and your smartphone near them pre bedtime this isn’t going to help. Particularly when it comes to establishing the melatonin rhythm. Being conscious of this is the very first (and powerful) step in helping them to establish a proper rhythm.

Why is melatonin so important?

Melatonin is known as the sleep hormone and in fact has its own circadian rhythm, linked to temperature and if established in the right way it rises before bedtime and stays high dipping as you come towards morning. Impacting the quality and depth of sleep.

What’s also interesting is the Melatonin is not only the ‘sleep hormone’ it is a very powerful antioxidant – click here for more on why these are so important to health and future health but is one reason why sleep and sleep cycles are so important to our health/the future health of a developing baby:  

‘Melatonin is known to be a potent antioxidant. One of the predictable consequences of a nocturnal melatonin shut off by light at night is, therefore, an increase in oxidative damage to biomolecules.’ (10)

Crucially research has found that blue light suppresses melatonin production and is very powerful altering circadian rhythms – more so than other wavelengths (10).

So low levels are not good for sleep or health in general.

Key action point: being conscious of blue light around a baby in the evening when you are trying to establish the sleep cycle is an easy yet powerful tool to help establish circadian rhythms in a healthy way. Simply reducing a baby’s exposure in the hours leading up to bedtime can be a very effective tool in helping establish their rhythm.

Next up: dim light:

This can be equally powerful if used in the right or even wrong way. Research has shown that ahead of bedtime when exposed to artificial ‘room light’ melatonin onset occurred on average 23 minutes prior to scheduled sleep. In dim light however, melatonin onset occurred 1hr 57 minutes prior to scheduled sleep.

Translation: those that were exposed to dim light vs bright artificial light ahead of bedtime lengthened their melatonin duration by 1hr 32 minutes. (9)

‘As a result of this exposure to electrical light between dusk and bedtime, pre sleep levels of melatonin were reduced by 71.4% and total daily levels of melatonin were reduced by around 12.5%’ (9) – that’s a lot!

That being said – you don’t want dim light during the day. The key is to restrict it to dusk and the approach of sleep. During the day is the time you want as much bright and natural light as possible:

‘Exposure to dim, warm-coloured light during the day may make matters worse. Studies have shown that higher levels of light during the daytime including exposure to daylight are associated with better sleep and mood.’ (5)

Key takeaway/action point: Bright light during the day and as you’re heading towards bedtime you want to dim that down and minimise bright light exposure as exposure to that between dusk and bedtime ‘strongly suppresses melatonin levels, leading to artificially shortened melatonin duration and disruption of the body’s biological signal of light’ (9)

Night lights: seemingly less of the ‘done thing’ these days. However, what has clearly been shown is that in order to establish a proper sleep and circadian rhythm: full darkness at night is the way to go:

‘When room light exposure continues for the entire night, total daily melatonin is suppressed by more than 50% in most individuals. These findings suggest that exposure to electrical light before bedtime and during the normal honours of sleep may impact physiological processes.’ The study also suggests that ‘individuals who habitually expose themselves to light during nighttime hours could have lower melatonin levels and puterbed rhythms.’ (9)

In fact dim lighting exposure on mice during the night actually induced anxiety like behaviour (1).

Bottom line: click here for the quick ‘how to’ on light/sleep but in a nutshell:

It’s surprisingly simple yet harder to do in our modern system – but – a bright/dark cycle is fundamental for establishment of a circadian rhythm and ultimately for protecting long term physical and mental health.

• Expose your baby to light as close to natural cycle as possible. Bright light during the day and dim light ahead of bed. Dark during the night.

• Avoid blue light exposure anywhere near scheduled bedtime (at least 90 minutes prior).

• Nightlights are not the one

• Invest in some good black out blinds for you/your baby’s room

• A new baby should start to establish sleep rhythms from the second month onwards but the earlier you can implement the above practises the better.

References:

(1) McGraw K, Hoffman R, Harker C, Herman J: The Development of Circadian Rhythms in a Human Infant: Circadian Rhythms

(2) Yates J: PERSPECTIVE: The Long-Term Effects of Light Exposure on Establishment of Newborn Circadian Rhythm: Journal of Clinical Sleep Medicine: 2018 Oct 15: 14(10): 1829-1830

(4) Lewis P, Erren T: Perinatal Light Imprinting of Circadian Clocks and Systems (PLICCS): The PLICCS and Cancer Hypothesis. Frontiers in Oncology. 2017: 7:44

(5) Lunn R, Blask D, Boyd W: Health Consequences of Electric Lighting Practices in the Modern World: A report on the National Toxicology Program’s Workshoip on Shift Work at Night, Artifical Light at Night, and Circadian DIsruption. The Science of the Total Environment: 2017 Dec 31: 607-608

(6): Charrier A, Olliac B, Todjman S: Clock Genes and Altered Sleep-Wake Rhythms: Their Role in the Development of Psychiatric Disorders. International Journal of Molecular Sciences. 2017 May: 18(5):938

(7): Brooks E, Patel D, Canal MM: Programming of Mice Circadian Photic Responses by Postnatal Light Environment: PLoS One: 2014: 9(5): e97160

(8): Kozaki T, Kubokawa A, Hatae K: Effects of day-time exposure to different light intensities on light-induced melatonin suppression at night. Journal of Physiological Anthropology. 2015: 34(1): 27

(9): Gooley J, Chamberlain K, Smith K, Khalsa SBS, Rajaratnam S, Rene E, Zeitzer J, Czeisler C, Lockley S: Exposure to Room Light before Bedtime Suppresses Melatonin Onset and Shortens Melatonin Duration in Humans: The Journal of Clinical Endocrinology and Melatabolism. March 11 Vol 96 Issue 3

(10): Bonmati-Carrion MA, Arguelles-Prieto R, Madrid JA: Protecting the Melatonin Rhythm through Circadian Healthy Light exposure. International Journal of Molecular Sciences. 2014 Dec: 15(12): 23448-23500

(11): Rivkees SA: The Development of Circadian Rhythms: From Animals To Humans: Sleep Medicine Clinics. 2007 Sept: 1: 2(3): 331-341

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