The important role blue light plays on regulating our sleep

by Rachel Lehen - Fatigue Management Solutions
Sunday , 17 October 2021 - 2-3 minute read
A woman in bed at night while on her laptop
Sleeping well

Let there be light! Light is the most important time setter for our body clocks. Over thousands of years, our bodies have evolved to follow a natural 24-hour light-dark cycle. In times past, if we were sleeping under the sky we would naturally sleep when it was dark and wake when the sun rises.

Nowadays, however, the truth is that too many of us in the real world spend most of our time indoors - at home, on the train and in our places of work. And the invention of the light bulb, invaluable as it may be, has wreaked havoc on our internal body systems by keeping us ‘switched on’ 24/7.

Messing with your daily routine

The best start to your day is to get the curtains open as soon as you wake, eat breakfast and get ready in daylight, then go outside. Sleep is controlled by biological, social, and environmental time-keepers. These include the light we are exposed to, the time-of-the-day when we eat our meals, exercise, interaction with others, and many more. When we stay indoors for a long period of time, we lose many of these cues. This can be challenging for a good night’s sleep and regular daily routines.

We are particularly sensitive to a wavelength (or colour of light) known as blue light. Because of its prevalence in the light given off by electronic devices such as computers and smartphone, blue light gets a bad rap. But in this case it’s not so much that it’s bad light – badly-timed light would be a more accurate description.

That’s because daylight is full of blue light, and during the day blue light is good. It helps set the body clock, suppresses melatonin production (sleep hormone) and improves alertness and performance. Once it’s dark however, these are all undesirable qualities.

If you’re using devices or have the lights blazing late into the night, then it's going to cause problems, leading to what Professor Chris Idzikowsi calls ‘junk sleep’ - disrupted and diminished sleep as our lifestyle and gadgets inhibit the production of melatonin and mess up our natural biorhythms1. This is even more detrimental for teenagers who in general have a delayed sleep phase (meaning they want to go to bed late) and then struggle to get up in the morning for school.

In short, blue light interferes with your sleep in two ways - firstly by disrupting your body's production of sleep-inducing hormones and secondly by throwing your body's natural circadian rhythm off balance. In fact, by negatively affecting the quality of our sleep, blue light exposure at the wrong time of the day can prove to be really detrimental to our health.

Breaking your rhythm

Many of us only really become conscious of our circadian rhythms if we fly long haul and experience jet lag, which is when our rhythms are out of sync with the local light-dark cycle because we’ve travelled so fast across time zones. It’s a similar story if we work a night shift and our hours are at odds with the light-dark cycle. But being aware of your body clock in your day-to-day life will help you begin to understand why you might be feeling lethargic at certain times of the day, and why you might be struggling to get off to sleep at night.

It’s not just your sleep that will benefit either - it’s the whole of your waking day.

With this in mind, here are some great tips for using light to help regulate your sleep:

Go towards the light

Get bright light into your eyes within a few minutes of getting up and seek light during the day. Our brain's body clock (or circadian pacemaker) is tuned by daily light. Morning bright light, when received by our brain at around the same time every day, is a powerful time signal for our body clock. Bright light has the added benefit of promoting alertness, which is particularly important if you find it difficult to get going in the morning. Try opening curtains and let in direct sunlight; if you don't have access to natural light, turn on bright indoor lights instead.

Separate daytime and night-time

Our body clocks benefit from keeping day and night clearly distinguished. During daytime, keep living space full of light, and keep active. For instance, organising, cooking, cleaning, and indoor exercises. In the evening, keep lights dim, and do quieter activities such as watching TV or reading.

Wind down at night

Keep lights dim (go for red or yellow lights - or even candlelight!) and block blue light on electronic devices 1 to 2 hours before bedtime. A dark environment can help your body naturally produce melatonin and prepare your body for sleep. To block out blue light from electronic devices, turn brightness of the screen to the lowest setting, and turn on apps such as f.lux (multi-platform) and Night Shift on iOS and Macs.

Following these three simple steps could really get your circadian rhythm back on track – and help you get a better night’s sleep of course!

With a background in natural health, Rachel has been specialising in the area of occupational fatigue management for the last 11 years, including regularly leading Fatigue Management Masterclasses, as well as presenting at a number of industry conferences to speak on the subject of fatigue management. Rachel facilitated NZ’s first research study on the prevalence of Obstructive Sleep Apnea in a Commercial Driver population, which was co-funded by ACC and the Log Transport Safety Council (LTSC). Rachel remains very involved with the LTSC’s efforts to identify & support high risk OSA drivers, and currently sits on the Sleep Apnea Association of NZ (SAANZ) committee.


1. Harding Medical Institute. The Dangers of Junk Sleep and What You Can Do About It.

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