If you’re having trouble sleeping, it may be your electronics.
As I wrote in How Light effects Melatonin and Sleep, the hormone melatonin helps regulate our sleep & wake cycles (the circadian clock). Production of this hormone is triggered by darkness and inhibited by light, and that helps explain why we have trouble with jet lag, shift work, and winter months with fewer daylight hours. But it’s not just the availability or intensity of light; it’s also the color temperature, and it’s been that way for thousands of years.
We’re genetically programmed to get sleepy at dark and wake in the light of day, but man’s DNA has not evolved as fast as electricity or electronics. The flickering flame of a campfire, with its warm orange glow, plays a role in getting our bodies ready for sleep, as does the bright morning sunlight that helps us wake up. So it’s not surprising that the cool blue light of a television, PC, or tablet does the same thing.
Screen size and distance also plays a role. As shown in the illustration, much less of the light from a 27″ TV across the room contacts the retina than the same TV placed closer, or a much larger TV at the same distance. Because of the wider viewing angle, even a notebook or tablet PC with a much smaller screen can flood the eyes with more light because it’s much closer, and that’s why viewing electronics before bed is a bad idea.
You can minimize the negative effects of the bluish light by simply turning down the brightness or changing the system settings so this happens automatically. My wife’s iPad-2 has a built-in camera, for example, so it can automatically adjust brightness to match the ambient room lighting, maximizing brightness in sunlight or minimizing it at night. My older iPad, on the other hand, has no camera or way to know if the room is bright or dark, so that feature doesn’t work on my iPad. I have to manually turn down the brightness, which I always do at night.
An even better solution would be if electronics also had the ability to adjust color temperature — giving the overall screen a more orange hue at night instead of bright white or blue. I looked for an iPhone or iPad app that does this, but none did it well. One new app, however, does show promise. It’s called f.lux, and I just started using the free Windows version, which seems to work quite well. They also have versions for Mac, Linux, and iPhone/iPad, but I can’t recommend the iPhone/iPad version since it requires a modification to the operating system, a risky process called Jail Breaking that adds complexity and voids the warranty. Still, the existence of f.lux shows that adjusting color temperature is technically possible, and I encourage Apple to add that feature in future versions of the operating system.
For More Information on Sleep & Health
Besides the many articles about Sleep here, I highly recommend the consumer education program at Harvard Medical School, which is available in the three links below and includes videos about Why Sleep Matters, The Science of Sleep, Getting the Sleep You Need, and Shaq on Sleep Apnea.