One Big Question: Does blocking blue light really matter?

There's an armada of electronic gifts about to descend on the world over the holidays, which means there will likely be even more people who won't be able to sleep in 2017 because they'll be going to bed with their tablets and smartphones. As those devices beam blue light at their eyes, sleep patterns will be disturbed and it's even possible that some cancer risks might increase. So what to do? Do blue-light-blocking glasses, screens and filters do anything to help?

To find out, as part of our regular One Big Question series, we asked Dr. Lakshmy Ayyar, assistant professor of medicine in the section of pulmonary, critical care and sleep medicine at Baylor College of Medicine, for her opinion. Here's what she had to say:

To understand the effects of blue light on sleep, let me start by explaining about our bodies' internal clock – the circadian rhythm, which regulates sleep. Circadian rhythms are approximately 24-hour cycles that influence consolidation of sleep and wake episodes and is critical for sleep health as well as for optimal functioning of other organ systems. It needs signals from the external environment to stay aligned.

The most important signals that adjust this rhythm are daylight and darkness. It is primarily light of a blue wavelength (blue light) that stimulates sensors in the eye to send signals to the brain's internal clock. Blue wavelengths are essential and beneficial during daylight hours as it helps us to stay alert and is known to boost performance and attention. However, the same blue light can wreak havoc on our sleep patterns!

Light emitting diodes (LEDs) are used in TVs, computers, smart phones and tablets. Although the light emitted by most LEDs appears white, LEDs have peak emission in the blue light range (400–490 nm). This essentially "tricks" our brains into thinking it is daytime. Exposure to blue light in evening can also suppress secretion of the hormone melatonin, which is another signal to regulate our circadian rhythm.

The easiest and most effective way to minimize blue light in the evening is to avoid looking at bright screens one to two hours prior to bedtime. Other ways to block blue light include the use of amber colored glasses and the installation of filter applications in your devices. Studies have shown that amber colored glasses increase production of melatonin and can lead to improvement in sleep. Filter applications automatically adjust the color and brightness of your screen and are effective in reducing exposure to blue light. No studies are published to-date to prove the impact on sleep with these applications, however this is an alternative for people who have to work late on their devices.

It is also important to expose yourself to natural sunlight during the day as this will help to entrain the natural circadian rhythm.

So there you have it. The short answer is that yes, it's worthwhile to block blue light if you or someone you know aims to use a device into the wee hours.

So if you're planning on gifting a phone or tablet this holiday season, you might want to load it up with a blue-light-blocking app like the well-reviewed Twilight (Android) or teach your gift recipient how to use "Night Shift Mode" on iOS devices. Or provide a screen protector such as Ocushield (which this writer has tried and liked) to not only let your recipient enjoy her gift, but to help her sleep well at night too.