I firmly believe that light and sleep are two of the most under-used tools for improving health (and that improper management of both are two of the biggest reasons for many health problems). Sound crazy? There is a lot of evidence to support the idea that certain types of light, especially blue light, can impact circadian rhythms and hormone balance in dramatic ways.
The Balance with Blue Light
Until 1879 when Thomas Edison patented the electric lightbulb, artificial lighting didn’t exist and after sunset, people relied on candles, lanterns, and fires for light.
After Edison’s patent, artificial lighting slowly became more widespread, but it has only been in the last century that we’ve seen the dramatic change from candlelight to mobile phone screens. Only three decades ago, a Harvard researcher discovered that light governs our internal clocks and we’ve been slowly learning more about blue light since then.
While a hundred years seems like a long time, it is a short amount of time in the spectrum of human history, and in the last few decades, we’ve started to understand how artificial light affects health. As the research continues, I believe that we will see more evidence that circadian rhythm interruptions from artificial light is partially to blame for many of the problems of modern society. Currently, we already know that overuse of artificial light and the resulting lack of sleep may be linked to certain cancers, increased risk of heart disease, and obesity.
Artificial lighting contains blue wavelengths of light that are absent in light sources like candles, lanterns, and fires. Blue light is known to improve alertness, mood and energy, and is important, but can be harmful if used at the wrong times of day.
How Light Impacts Circadian Rhythm
The body has built in systems that help regular circadian rhythm, and it relies on outside input (especially blue light) to signal times the body should be awake vs times it should be sleep. In other words, there are abut 30,000+ cells in the eye that sense blue light and these cells signal the brain to turn off melatonin production. Melatonin is necessary for sleep, and when it is suppressed at night, when it should be increasing, it can affect sleep quality.
Blue light wavelengths would be seen in nature during the brightest hours of the day and are found in sunlight. These wavelengths are not present in fire or other natural light sources that would have been used at night. Ever sat around a campfire at night? Most people describe natural light sources like fire as being soothing and promoting sleep, largely because of their lack of blue light (and obvious natural beauty).
At the end of the day (pun intended), it is all about timing. Blue light during the day is beneficial in many ways, including:
- Sending the correct signals to the brain for proper melatonin production
- Promoting mood and alertness (in fact, it may be better than coffee!)
- Signaling the body to maintain healthy weight and adrenal function
These are all vital during the day. In fact, my doctor uses the timing of blue light and carbohydrate intake to help balance cortisol and other hormones. Other doctors use blue light therapy during certain times of day to help address sleep disorders, seasonal affective disorder and other disorders.
The problem occurs when a person is routinely exposed to blue light in the evening after the sun has set, especially when this happens daily over long periods of time. This confuses the body’s natural rhythms and signals a reduction in melatonin, which is necessary for sleep.
Harvard Medical School has been studying the affects of blue light:
A Harvard study shed a little bit of light on the possible connection to diabetes and possibly obesity. The researchers put 10 people on a schedule that gradually shifted the timing of their circadian rhythms. Their blood sugar levels increased, throwing them into a prediabetic state, and levels of leptin, a hormone that leaves people feeling full after a meal, went down.
Even dim light can interfere with a person’s circadian rhythm and melatonin secretion. A mere eight lux—a level of brightness exceeded by most table lamps and about twice that of a night light—has an effect, notes Stephen Lockley, a Harvard sleep researcher. Light at night is part of the reason so many people don’t get enough sleep, says Lockley, and researchers have linked short sleep to increased risk for depression, as well as diabetes and cardiovascular problems. (1)
Other studies have looked at shift workers, who are routinely awake and exposed to blue light at night, and some have found that simply blocking blue wavelengths can help reduce the negative effects.
Studies have also found that blue light can have a negative impact on hormone levels and circadian rhythm, even if we don’t consciously notice the effects. While blue light may be a factor in the increasing rates of sleep disorders, it may also be causing problems for those of us who don’t notice its effects.
Sources of Blue Light Exposure
Most of us are exposed to much more blue light that we realize. Sources include:
- Sunlight (the biggest source)
- Electronics like TVs, phones, tablets and computers
- Light bulbs and other sources of artificial lighting (LED bulbs are especially harmful)
Sunlight is an important and beneficial source of natural blue light and it is beneficial to be exposed to blue light during the times of day that we can be exposed through the sun. This also makes it impossible to get improper blue light exposure from the sun, as blue light from the sun naturally signals correct circadian rhythms.
Unfortunately, artificial light sources make it possible to get blue light at times of day that we are not biologically designed to handle and this can affect hormone levels and decrease sleep quality. In essence, these artificial lights trick our bodies into thinking it is daytime and suppress the hormones needed for sleep. This is great during the day but harmful at night.
Thanks to recent research, many people are aware that looking at a screen before bedtime isn’t great for sleep, but additional research is showing that indoor light bulbs, especially LED bulbs, may be even more problematic:
The paper Exposure to Room Light before Bedtime Suppresses Melatonin Onset and Shortens Melatonin Duration in Humans, found that exposure to room light before bedtime suppressed melatonin in 99 percent of individuals and shortened melatonin duration by about 90 minutes. (2)
This is a drastic difference and it occurs just from exposure to normal room lighting. If our lightbulbs (especially LED bulbs that are gaining popularity) suppress melatonin in 99% of us, and virtually all of us in the developed world are exposed to it in some form nightly, is it really a surprise that we are seeing a drastic rise in disorders related to circadian rhythm disregulation?
This is also why programs that reduce blue light on screens like f.lux are beneficial but don’t solve the problem completely.
What About Red Light?
While bright lights with blue wavelengths can be stimulating and suppress melatonin, red lights do not have this same effect and may not only be a good alternative, but may have their own benefits. We’ve likely all had the experience of a great night of sleep while camping and sitting around a campfire or enjoying a peaceful evening of candle light when the power has gone out. Lack of blue light and exposure to red light may be why, and red light may have benefits for hair, skin and joints as well:
There is a body of evidence that light in the red spectrum triggers collagen synthesis. More collagen in the skin means less wrinkles and healthier skin. Since red light also has no blue spectrum, I use red light at night when it’s convenient. It’s surprisingly simple to install a $25 remote controlled stick-on color LED lighting strip over your bed. Better still, red light triggers the cellular power plants called mitochondria to work better through something called the mitochondrial transport chain. When your cellular energy is higher, you sleep better and you have more energy during the day. (3)
Since red light does not reduce melatonin levels like blue light does, it is a better choice for use at night, and some people find that using orange or red lightbulbs at night helps improve sleep quality. Wearing Blue Light Blocking glasses, which block most blue light, are another option for avoiding blue light at night and this addresses room lighting as well as phone, computer and tablet exposure.
How to Optimize Blue Light Exposure
As with most things in nature, blue light is neither good nor bad, but the timing and the amount makes all the difference. Avoiding blue light entirely would be just as harmful (or more so) than night time blue light exposure, but understanding how light affects circadian rhythms allows us to use blue light to improve health.
Action Steps to Hack Blue Light
- Blue light is very important during the day and we should make a point to get exposure to natural sources daily to help support the body’s natural circadian rhythms. TIP: If you can’t get outside during the day or you don’t live in a sunny area, my doctor suggests a 10,000 lux light box as a good alternative for use in the morning.
- It suppresses melatonin at night, so avoiding blue light for 2 hours before bedtime can be really beneficial. This can be done by avoiding bright light in the home, not watching screens and using blue-blocking glasses after sunset. TIP: I use these inexpensive and ugly orange glasses at night after sunset.
- Consider using red or orange toned bulbs in lamps at night in place of bright room lighting. Programs like f.lux can also be helpful, but since room lighting can have much more blue light that a computer screen f.lux will only be helpful if room lighting is addressed as well.
- Remove sources of artificial light (alarm clocks, night lights, etc) in sleep areas. TIP: Here are some other good tips for optimizing sleep environment.
Do you take any steps to avoid blue light at night or get natural exposure during the day?