How blue light affects your sleep

Without doubt, blue light affects our sleep.  There’s been a number of important studies demonstrating the disturbance that losing our connection to the natural light-dark cycles have created in our sleep patterns.

Linda Geddes from BBC future did a fascinating experiment by living for a period without artificial lights and screens.  The first week she maximised her exposure to natural daylight.  She moved her desk next to the window, spent time in the park on her way to drop the kids off at school and tried to get outside at lunchtime.

The next week, she lived as normal.  The week after that she combined the extra exposure to natural daylight with using only candle light or red dim light after 18.00!  She tracked her responses.  She completed sleep diaries and questionnaires to assess sleepiness and mood in addition to various cognitive tests to assess short term memory, attention and reaction speeds.  On the last evening, she spent her evening in darkess whilst taking hourly melatonin samples.

The findings were as I would expect…

She said “I was significantly sleepier in the evenings during the increased daylight and low evening light. My body also started releasing the darkness hormone, melatonin two hours earlier when I avoided evening light”

You can see the full article on the experiment by clicking here

I truly believe that our modern day lifestyles of staying up late and in particular staring at our screens has a terrible effect on our sleep.

The truth is that all artificial lighting can affect our sleep levels. Electric lighting is such a commonplace part of our lives. It’s hard to imagine it might be causing any sort of problem for us but actually it’s probably the one modern invention that has had the largest impact on our sleep.

If you think about the days when there was no electric light, peoples lives were largely governed by the rising and setting of the sun. On cold Winter nights when it was dark by 5pm, people didn’t sit up until 10 or 11 playing video games – or even reading a book. They had a candle or lamp to allow them to do the basics, and then off they went to bed.

Our circadian rhythms are governed by the rising and setting of the sun…

…except, electric light confuses our circadian rhythms.

Now that we can have our environment as light as day (or lighter!) twentyfour hours a day.  Is it any wonder we’re knocked off balance?

Even when we switch the lights off at bed time, there’s often light from the street lights outside, and we’ve spent our entire evening bathing in artificial light. Then there is the LED alarm clock on the bedside table, the stand-by light of the TV in the corner, your mobile screen lighting up periodically throughout the night… do you see what I mean?

Between the years 1950 and 2000, our use of artificial light has quadrupled.

…and our sleep problems have followed the same trajectory. Artificial light allows us to stay up later, and then we just use caffeine in the morning to perking ourselves up making up for the missed hours. Over time, our natural balance goes completely AWOL, and we’re left unable to either sleep or wake up properly.

The University of Colorado did a study and found that camping in nature with no artificial light can help to “reset” our systems. One week camping with only a campfire for light after dark can help our circadian rhythms return to their natural balance.

Anyone for camping?  Could be glamping as long as it’s candle light?


Circadian rhythm blue light affects our sleep


There is now an abundance of experimental evidence in humans that electric light during the night and altered sleep patterns can disrupt circadian rhythmicity in hormones, circadian gene expression, markers of metabolism and many other physiological parameters.  (Royal society of publishing)

It’s also worth noting that those clever new LED energy saving light bulbs are actually serving to confound the problem.

Even 15 or 20 years ago, the lights we had in our homes were a lot less bright.

These days, our bulbs are super bright, and giving out that pesky blue light – the same as we get from our TV screens and mobiles. Blue light stimulates our brains and wakes us up, whereas more orange, red light is less likely to stimulate wakefulness.

If you can’t bear the thought of a week in a tent, you could try replacing your energy saving light bulbs with red or orange tinted bulbs – at least in the bedroom and bathroom. If you can’t change your bathroom light source, try using small, battery-operated lamps or maybe even candles if you can position them safely.

Using this more gentle light in the evenings may well make the difference you need, to get a good night’s sleep!

Interested to know about your melatonin levels, click here