In our pursuit of energy efficiency, we’re finding ourselves exposed to greater amounts of blue light than ever before. Unfortunately, many energy-efficient light1 sources2 (such as CFLs and standard LEDs) produce high concentrations of blue light. Blue light is emitted by electronic devices, most energy-efficient light bulbs, and other common light sources. High-efficiency light bulbs, as well as digital devices including smartphones, tablets, and computers, emit high concentrations3 of blue light. Blue light appears to be uniquely detrimental to our sleep.
Scientists have discovered that a light-sensitive layer of the eye, which is different from the part that allows us to see, sends signals to the body that affect rhythms of wakefulness and sleep. We’re continuing to learn more about the stimulating effects of blue wavelength light and its capacity to disrupt sleep. Exposure to artificial light at night is recognized4 as a hazard to sleep, contributing to rising rates of disrupted and disordered sleep. Different wavelengths of light have been shown to affect human physiology and sleep cycles in different ways. Blue light, a short-wavelength light, has been singled-out5 as more significantly disruptive to sleep than other colors on the light spectrum6. Research has shown blue light delays release7 of the sleep hormone melatonin, disrupts8 circadian rhythms, and may influence negative changes9 to mood.
The disruptive effects of artificial light on sleep are well documented10, and have received11 an increasing amount of attention in recent years—with good reason. Nighttime exposure to artificial light—which for the great majority of us happens without much thought or awareness—disrupts the body’s circadian rhythm, altering12 the 24-hour biological clock that controls our sleep-wake cycle. In addition to wreaking havoc with sleep, disruptions to circadian rhythms also have been associated with a number of serious diseases, including cancer13, diabetes14, depression15 and heart disease.
A new study further examines16 the stimulating effects of blue wavelength light, focusing on the effects of daytime exposure to the short-wavelength light. Researchers at Boston’s Brigham and Women’s Hospital and Philadelphia’s Thomas Jefferson University investigated 17 the effects on alertness and cognitive performance from prolonged daytime exposure to blue light. They also compared the daytime effects of blue light exposure to the effects of evening exposure to the same degree of light. Their findings confirm that blue light at night stimulates alertness and diminishes feelings of drowsiness, interfering with sleep. Exposure to blue light during the day, however, results in a similar, more welcome boost to alertness and reduction to fatigue, which stand to benefit both daytime function and nighttime rest.
These current finding also indicate that blue light hinders sleep in ways beyond the delayed release of melatonin, and alteration to circadian rhythms. Exposure to blue light at night spurs cognitive function and alertness in ways very similar to daytime stimulation, a change that can make sleep significantly more difficult to achieve.
Exposure to artificial light at night—especially to the high concentrations of blue light coming from digital devices—will interfere with the ability to sleep. Too often, these devices find their way into our bedrooms18, in many instances even to be used as alarm clocks. The presence of artificial light from devices like smartphones and tablets in the bedroom poses a challenge to the darkness19 that is so important to normal circadian rhythm function. This nighttime light intrusion also stimulates alertness and brain activity that is counterproductive to the mind and body’s natural pull20 toward sleep.
Some companies are now putting warning labels on light bulbs to help educate us on how light can be helpful by day, yet hazardous at night. Solutions to this issue are available in the form of specially filtered bulbs that can be used in the evening hours, but still give off enough light to read, etc.
In order to help ourselves sleep at night I recommend the following:
- Remove electronics that you don’t need, including television (unless you require it to get to sleep—for some it’s relaxing), computers, laptops, and cell phone.
- Avoid having the kind of alarm clock-radio that emits a strong digital light, especially a blue one. If your sleep patterns are regular, see if you can go without an alarm clock at all!
- Use black electric tape to cover up any lights shining that are inevitably part of your bedroom setting.
- Get light exposure during the day. Daytime exposure to light—both sunlight and artificial light—can help strengthen circadian rhythms and boost daytime alertness, leaving you better prepared to sleep when the time comes.
- Don’t forget to check outdoor lights, too. If a backyard or front light is shining too brightly, or in the direction of a window, it could be disrupting your sleep.
- If you need access to light in the middle of the night, use small nightlights. Rather than switching on hallway or bathroom lights—and flooding your system with melatonin-suppressing light—use low-illumination night lights to guide you when you need to get up in the dark.
- Make the last 60 minutes of your bedtime ritual electronics free—and keep electronic gadgets and devices out of the bedroom altogether.
- Look for lighting products that emit less blue light, so that your sleep is not disrupted. For more information on this topic just search “health labels on light bulbs.”
Being aware of the effects of nighttime exposure to light and making some basic changes to bedtime routines can go a long way toward getting you the darkness you need to sleep well, even in this ever-bright modern age.