Before we were even walking on two legs, our bodies had evolved to use sunlight as the primary signal for sleeping and waking. Neuroscientists have shown that a narrow portion of sunlight, along the blue spectrum, is especially important for us. Special photopigments in our eyes called melanopsin receive this wavelength and use it to send a signal that eventually wakes the body. But blue light does more than wake us up, it acts like a stimulant and has been shown to boost attention, reaction times and mood. Light-therapy boxes that push out powerful amounts of blue light have been used to treat conditions like depression, eating disorders and age-related dementia. In fact, they’re so useful for improving mood and alertness for people who need a boost that you can now buy them online. They’ve helped a lot of people, but one thing is certain – they’ve only helped during the day.

Although any kind of light can keep us awake, blue light sends the strongest signal to our bodies. In an experiment at Harvard, 1.5 hours of blue light had the same effect as 3 hours of green light on suppressing melatonin. Unfortunately for the modern homo sapien, blue light is emitted from the technology we’ve surrounded ourselves with: laptops, televisions, cellphones, and LED light bulbs. Worse, these devices are actually “short-wavelength enriched,” meaning they have a higher concentration of blue light than natural light. To get better sleep, we need to reduce our exposure to blue light at least two hours before bedtime. But that is seriously difficult to do!

Three Ways to Reduce the Power of Blue Light

This simple change can make a big difference. Turn off most of your lights and just use one or two lamps to keep things dim. Think mood lighting, not getting ready for work lighting. Get in the mood… to go to sleep.

In the battle against blue light, Android users win – there is a convenient app called Twilight that cuts out the blue light across the entire device. For iOS users, unfortunately there are no great apps to reduce blue light, but there are simple settings you can change that will make it easier to read on your phone at night.

For iPhone users the simplest way to reduce blue light is to invert colors under the Accessibility settings. It turns whites to blacks and blues to reds, so the light your phone pushes out is much, much dimmer. This isn’t the perfect solution, but it makes a huge difference when you’re using your phone at night.

 f.lux is is good stuff. It’s a popular application that turns down the blue light on your computer monitor based on the time of day and when you prefer to fall asleep. It asks for your timezone and then lowers your monitor’s blue light levels as the sun sets. This is a fantastic tool to help with your sleep – you can really feel the difference as it gets later in the evening and the screen grows dimmer. F.Lux is a powerful tool that is somehow free, for both Window, Macs, and other devices. After you install the program on your computer (here is the link) and set your times, make sure it’s allowed to start up automatically when you power up your computer. After that it’s on autopilot and you won’t even notice it – you’ll just notice that you’re feeling sleepy as it gets later… perfect!

Make a Change

Here is a simple experiment you can try that shows the power of light: When you go to bed tonight, have the lights off and open your iPhone with the screen on its dimmest setting. Then use the instructions above to invert the colors. Pay attention to how your eyes feel as well as the rest of your body. You should feel an immediate relaxation as your body adjusts to the dimmer light. If you really want to feel how artificial light affects your sleep, you can try cutting it out for one month like JD Moyer did, but this simple experiment should be sufficient.

Consider installing f.lux, and definitely consider turning down the lights as bedtime draws closer. You’ll notice the difference right away!

References and Additional Resources

http://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side – Harvard Medical School warning about blue light and sleep
http://www.pnas.org/content/112/4/1232 – reading an iPad before bed is terrible for your sleep
http://www.scientificamerican.com/article/q-a-why-is-blue-light-before-bedtime-bad-for-sleep/ – two neuroscientists discuss light and sleep
http://psycheducation.org/treatment/bipolar-disorder-light-and-darkness/light-therapies-for-depression/ – Light has powerful effects
http://www.ncbi.nlm.nih.gov/pubmed/16165105?dopt=Abstract – Light therapies have been around a long time
http://www.ncbi.nlm.nih.gov/pubmed/25780235 – Links artificial light and lower melatonin production to shortened lifespans
http://www.ncbi.nlm.nih.gov/pubmed/22850476 – The blue light from iPads is terrible for your sleep
http://jdmoyer.com/2010/03/04/sleep-experiment-a-month-with-no-artificial-light/ – Great read on the benefits of reducing artificial light