We learned this week that Apple is moving toward making its handheld devices more sleep-friendly. Included in an upgrade for Apple’s iOS operating system is an app called “Night Shift,” which changes the color balance of light from device screens during evening hours. The Night Shift app uses GPS data and user settings to adjust the composition of screen light after sunset, reducing white and blue light while increasing red and orange light. The upgrade (iOS 9.3) and the app itself are not yet available to the general public, but are currently in beta testing.
The Effects of Light on Sleep
What does the color of artificial light have to do with sleep? A lot, according to scientific research. Exposure to artificial light at night is one of the most widespread and significant disruptors to sleep. Blue light is particularly aggressive in its disruption to sleep and to circadian rhythms (our body’s internal clock), according to a deep and growing body of scientific study. The screens of many digital devices, like phones, tablets, computers, and other LCD screens, emit high concentrations of blue light, which is what the Apple upgrade is trying to tackle.
The addition of this feature to Apple’s hand-held operating system is an important step in the right direction. Effective reductions to blue light exposure are likely to benefit sleep and overall health. The company deserves acknowledgment for recognizing this health issue, and taking steps to integrate light controls like these into their handheld devices.
But the problem of light to sleep and health is bigger than Apple, and more pervasive than the ubiquitous smartphones that are so often shining brightly at night. As worthwhile a move as this is by such a high-profile company, it doesn’t—it can’t, really—go far enough to correct the toxic health problem that excessive exposure to light poses. Light at night should come with a warning label, plain and simple.
By impeding healthy, abundant sleep and interfering with circadian rhythms, the consequences of unhealthful light exposure reach into nearly every aspect of life, including health, safety, productivity, and relationships.
Insufficient sleep and circadian rhythm dysfunction are linked to:
- Cardiovascular disease
- Type 2 diabetes
- Sleep disorders, including insomnia
The Epidemic of Light Pollution
While these ever-present devices—our smartphones and tablets—certainly contribute significantly to the problem, our unhealthful exposure to light existed before most of us had smartphones.
We live in an environment saturated with light. Think about all the sources of artificial light you encounter in a typical day. There’s the light in your home, the streetlights that shine through your bedroom window, the television and computer screens we log hours in front of after the sunsets. And yes, there are our phones, which too often reside on the bedside table.
In today’s world, darkness—essential for sound, plentiful, high-quality sleep—must be sought out, and is often difficult to achieve. Darkness triggers critical physiological changes that pave the way for sleep, including the release of melatonin, a hormone that plays a central role in regulating circadian rhythms and enables normal sleep-wake patterns. Exposure to light in the evening hours can significantly delay the release of melatonin and shorten the length of time the body produces melatonin. Both of these changes disrupt normal circadian function and sleep. It’s not only light from smartphones or other devices held at close range to the face and body that have this negative impact. Research shows that typical room lighting in the hours before bedtime exerts a high degree of disruption to melatonin release and duration.
Blue light, as a growing body of research demonstrates, is an especially aggressive disruptor of melatonin, circadian rhythms, and sleep. Studies indicate that blue light may be twice as potent a melatonin-suppressor as other light wavelengths. Efforts to improve energy efficiency have increased our exposure to blue light. That’s because blue light is emitted in higher concentrations in many energy efficient light sources, including LED and other energy-efficient lighting and LCD screens for digital and electronic devices.
To truly address the health problems that result from excessive light exposure will require a comprehensive environmental solution. Personally, I use lighting products that filter blue light so that light is not a factor for my family or myself in the evenings. These types of products, in conjunction with new technologies like the one Apple is going to deploy, are empowering steps that enable us to create healthier environments for ourselves and our families.
What Are the Risks?
Light pollution and its negative effects to human health and safety are an important public health issue, one that continues to be overlooked. The harmful effects of excessive and poorly timed light exposure need systemic investigation and attention. At the same time, we don’t need major policy breakthroughs to begin to make positive changes in our own lives. We can all pay more attention to how we use light, particularly the ways and degrees to which we extend daylight artificially in the evenings or very early mornings. We can use products that address this issue in our homes and places of employment.
Handheld devices like smartphones are one of several considerations, and Apple is taking an appropriate initial step with Night Shift. But we all need—individually and collectively—to think bigger, broader, and much more about darkness if we’re going to effectively address the health threats of persistent and excessive light exposure. Light is medicine, and we need to understand and respect it.