Blue light and its effects on sleep.
Blue light is one type of visible light that is part of the electromagnetic spectrum. Visible light on the electromagnetic spectrum ranges in color from red to purple like the colors of the rainbow. When light gets separated into its component colors, like when we shine a beam of light through a prism, you can observe the separation of each individual wave of light. Each wavelength of light and each color of the light represents a different size wavelength and frequencies of the waves that range from small or shorter lengths to longer or larger lengths.
Visible light ranges from 400nm to 800nm and as mentioned ranges from violet to red. Light below the spectrum, under 400nm is consider ultra violet light of which there are 3 primary ranges UVA, UVB and UVC. Ultra violet light is the type of light that causes sunburn. Light beyond the 800nm is considered infrared light, which is hotter than visible light. Although we experience ultra violet and infrared light in our everyday lives, it is light that the human eye can not see.
The shorter wavelengths of blue light can affect the way we sleep. Our bodies have a kind of internal clock. That internal clock can prepare our bodies to get ready for sleep and can tell our bodies when it is time to wake up. There are other factors, such as our body temperature and the changes that occur while sleeping. Generally, our body temperature will begin to drop a couple of hours before we are ready to go to sleep and begin to rise again preparing our bodies to wake up in the morning.
The cycle of these internal rhythms that effect many bodily functions are known as our circadian rhythms. One of these rhythms known as the sleep-wake cycle is affected by blue light. This particular blue light has a significant affect on the melatonin levels in the body. As the melatonin level rises it helps prepare and allows us to sleep comfortably.
When exposed to blue light, particularly later at night prior to getting ready for sleep, the production of melatonin, which is a hormone that regulates our sleep and wake cycle, is suppressed, and can cause a disruption in that sleep-wake cycle.
Basically, it goes like this. As you approach the time you are ready to go to sleep, when on your computer, watching tv, tablets, and/or smart phones, the production of melatonin gets suppressed.
Melatonin gets suppressed due to the exposure to blue light just prior to sleep, as the blue light interferes with the body’s natural production of melatonin. This can make it harder to fall asleep. Not only does it become harder to fall asleep, it can make it more difficult to stay asleep.
The blue light exposure also can disrupt the body’s circadian rhythm. When this happens, the body’s natural internal clock becomes confused and can prevent the body of having a restful sleep and you can wake up and fall back asleep, or cause you to have interrupted REM and deep sleep, both which are needed for a good night’s sleep.
All which can lead to a poor night’s sleep and limited the amount of time we sleep.
So, what can we do to ensure that blue light does not have an impact on a good night’s sleep.
- Limit the amount of time on electronic devices for 1-2 hours prior to going to sleep.
- Use blue light filtering glasses. Blutech lenses and similar lenses available in prescription and non-prescription are available from your local Optician or Optometrist office.
- Some electronic devices have filters you can set or activate. While many manufacturers of these devices have had to change the name designation of this function from “blue light filter” to comfort light setting (or something synonymous with that phrase) because it doesn’t necessarily filter the blue light, but it reduces the brightness and simulates the harshness of the light being emitted by the electronic device.
- Use less harsh light prior to going to sleep and create a regular routine for bedtime sleep, so that you will be more relaxed before sleep time. For example, it would not be a good idea to do your exercise routine just prior than going to sleep, thus raising the body’s temperature, thus throwing off your body’s readiness for sleep.
Other factors about blue light. Light in the morning, in particular, blue light is important for regulating circadian rhythms. Since daytime sunlight produces more blue light than during sunset, exposure to blue light during the day keeps your body’s rhythm on track. Unless of course your job requires you to work during the evening into the morning. You would want to avoid over exposure to that morning day light, as it can cause havoc to your daytime sleep. For those who work during the daytime, blue light can help us be more alert, improve memory and maintain good reaction times while performing functions at work or leisure.
For nighttime, try to reduce exposure to blue light, mainly from electronic devices, fluorescent lights, and LED light. This in addition to all of the effects of blue light already discussed.
Light can be a tricky thing. As an Optical Health Care Professional, I often counsel patients on the effects of light on the eyes and body. An example of this in addition to the effects of blue light, bright light can be problematic too, particularly for folks as we age. One of the first questions I ask a patient prior to going in for their eye exam, is, “how is your night driving?” When they respond with the typical, I have been having more trouble seeing at night, than I used to. The next question I ask is, “let me see your sunglasses.” That is when I get the awkward looks, and the response, what does sunglasses have to do with my night driving? Just like filtering blue light for a comfortable sleep, our eyes have millions of rods and cones in our eyes. The cones regulate how we see color and the rods regulated how we see in low light situations. Over exposure to bright light during the day, can cause our night vision to become suppressed, making it difficult to navigate during the night. Much like a camera flash to the eye or staring at a bright light for several seconds. It takes time for the eyes to recover and as we get older those light receptors become more sensitive to bright lights, in a similar concept to being affected by blue light.
So, to all you fellow MUGsters. Make sure you wear a quality pair of sunglasses during the day to protect your eyes from bright light and UV light and if you are a night owl who loves to be on your electronic devices up until the time you are ready for sleep, get yourself a quality pair of blue light filtering glasses.
If you were wondering. Can blue light cause damage to your eyes? While we know the effects of blue light can cause eye fatigue, sleep disruption, dry eyes, digital eye strain, there have been no definitive studies that provide that blue light actually damages the eye. Unlike prolonged UV exposure can cause physical damage to the eye and eye structure, and contribute to the development of cataracts, macular degeneration, and photokeratitis. Thus the need for quality sunglasses.