Blue light is much more common in our environment than it ever has been. It’s affecting your eyes right now as you read this on your computer screen or device. I’m not going to tell you it’s all bad. In fact, sunshine has been providing our eyeballs and brain with a source of blue light since the very beginning of time.
The problem is that our brains are still very much attuned to natural rhythms of dark and light. When bright sunlight hits the backs of our retinas first thing in the morning, it actually helps us wake up. Melatonin production is turned off and cortisol production begins. Cortisol should be at its highest levels first thing in the morning.
Throughout the day, cortisol levels will gradually decline, with the lowest levels occurring just after dark. Since cortisol is antagonistic to melatonin, it is extremely important that this occurs. People who have trouble falling asleep at night, especially if they feel their minds are too ‘busy’ to fall asleep, often have cortisol levels that are too high in the evenings.
This often happens due to stress, but it also occurs because of all the stimulatory blue light we expose our eyes and brains to at night!
In the evenings and after dark, the bright, blue wavelength light fades away in favor of the orange wavelengths. Without the blue wavelengths stimulating the pineal gland and the rest of the mesencephalon (the top part of your brainstem), cortisol production decreases and melatonin production proceeds.
What’s interesting to note is that melatonin may do more than just help us sleep. There is research that suggests it has cancer-fighting properties; that one of the important things that happens while we sleep is immunosurveillance for precancerous and cancerous cells. In this study, women who worked at night had an elevated risk of breast cancer. Here, it was associated with an increase incidence of colorectal cancers (see citation 12-17 in this last article for physiological mechanisms of melatonin’s anti-cancer properties).
So we need to limit our exposure to blue light after sundown, but how? One of the biggest ways is to eliminate the use of electronic devices at night. Smartphones, tablets, and laptops have all become regular interlopers in our evening routines. For purposes of stress reduction as well as melatonin, it would be optimal to not use these device at all after sunset.
That may not be reality for most of us though. I use a free program on my laptop called f.lux that determines what time of day it is in my next of the woods and then automatically filters out the blue light from the screen. You have to jailbreak your phone or tablet to use it on those devices and I’m not just not up for doing that, so if I have to use one of those devices, I wear a pair of orange googles that filter the blue light. Rumor has it that the new iOS update (9.3) includes a native blue-light filter function , though my phone is not new enough for me to have tried this personally.
One thing I would like to note here- though there are ways to mitigate the harmful effects of blue light exposure at night, that doesn’t mean you can continue using your device at night with impunity. The postures we tend to use when staring at a small screen, as well as the effects to the muscles of our eyes from focusing on a close up object for long periods of time, all take their toll on our bodies and our health as well. For some of us, the stress caused from social media interactions can be detrimental. For these reasons, it would be best not just to mitigate the harmful effects of blue light, but also to be more conscious and aware of our electronic usage in general. You’ll probably find more high quality, fulfilling interactions with the people next to you then the ones on the other side of the electrons.
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