How Can Blue Light Affect Sleep?
Sleep hygiene suggests sleeping in a dark room, and most people do turn off their lights at night, but quite often, they leave something on in the background that they don’t think is very disturbing – blue light, which is now known to be especially disturbing to sleep.
Blue light is emitted by electronics and energy-efficient light bulbs. Too often people leave their electronics glowing in the background as they sleep-laptops, electronic screens and clocks, etc. without knowing that these may be disrupting their sleep.
Light at night tends to throw off the body’s biological clock, which is the circadian rhythm, and sleep disorder suffers get the worst of it. Also, research indicates that this may contribute to prevalence of cancer, heart disease, diabetes and obesity.
However, not all colors in the light spectrum have the same effect. It’s blue wavelengths that seem to be most disruptive at night. It’s no wonder since blue light is so helpful in daylight, known for boosting attention, reaction times, and even in elevating mood. The prevalence of electronic devices with screens is exposing us to more and more blue light, especially at night.
The average length of a circadian rhythm is a little more than 24 hours, and Dr. Charles Czeisler of Harvard Medical School demonstrated in 1981 that daylight aligns an individual’s circadian rhythm with the environment. Interrupting this natural rhythm can cause health problems as evidenced by many studies linking night-shift-workers and their unusually long exposure to light with various diseases, including cancer, heart disease, diabetes and obesity.
Though it is not yet clear what about the exposure to light at night is so harmful, we have learned that it suppresses the production of melatonin-a hormone known to influence circadian rhythms, and some experimental evidence has linked lower levels of melatonin with some types of cancer. Yet shifts in circadian rhythm is more clearly linked to diabetes and obesity based on research that demonstrated increased blood sugar causing a pre-diabetic state and reduced levels of leptin-a hormone that alerts the body when it’s full.
Any kind of light, even dim light, can suppress melatonin, blue light has the most powerful effect. In a Harvard research study, comparing the effects of 6.5 hours of exposure to blue light versus green light, the blue light showed dramatically increased affects, suppressing melatonin for double the time of the green light and shifted the circadian rhythms almost twice as much.
A similar study was conducted in Canada, which demonstrated that exposure to blue light and full spectrum light had similar affects in reducing the melatonin hormone, reinforcing the strong disruptive nature of blue light. The effects of blue light on disrupting hormones and interfering with circadian rhythms is along with the correlative health risks suggests that people should take measures to end their exposure to blue light at night, including turning off electronic devices or even removing them from sleeping areas in particular. Also, you could consider using low red lights for night lights; avoid looking at computer, tablet and television screens before bed, if you work a night shift, consider wearing blue blocking sunglasses; take in a lot of sunshine during the day when possible, which should help you sleep at night and may help boost your mood.
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